Skip to content
This repository

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
branch: master
Fetching contributors…

Cannot retrieve contributors at this time

file 10016 lines (9502 sloc) 387.744 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059 2060 2061 2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180 2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212 2213 2214 2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305 2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316 2317 2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344 2345 2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440 2441 2442 2443 2444 2445 2446 2447 2448 2449 2450 2451 2452 2453 2454 2455 2456 2457 2458 2459 2460 2461 2462 2463 2464 2465 2466 2467 2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755 2756 2757 2758 2759 2760 2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776 2777 2778 2779 2780 2781 2782 2783 2784 2785 2786 2787 2788 2789 2790 2791 2792 2793 2794 2795 2796 2797 2798 2799 2800 2801 2802 2803 2804 2805 2806 2807 2808 2809 2810 2811 2812 2813 2814 2815 2816 2817 2818 2819 2820 2821 2822 2823 2824 2825 2826 2827 2828 2829 2830 2831 2832 2833 2834 2835 2836 2837 2838 2839 2840 2841 2842 2843 2844 2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856 2857 2858 2859 2860 2861 2862 2863 2864 2865 2866 2867 2868 2869 2870 2871 2872 2873 2874 2875 2876 2877 2878 2879 2880 2881 2882 2883 2884 2885 2886 2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920 2921 2922 2923 2924 2925 2926 2927 2928 2929 2930 2931 2932 2933 2934 2935 2936 2937 2938 2939 2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980 2981 2982 2983 2984 2985 2986 2987 2988 2989 2990 2991 2992 2993 2994 2995 2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 3030 3031 3032 3033 3034 3035 3036 3037 3038 3039 3040 3041 3042 3043 3044 3045 3046 3047 3048 3049 3050 3051 3052 3053 3054 3055 3056 3057 3058 3059 3060 3061 3062 3063 3064 3065 3066 3067 3068 3069 3070 3071 3072 3073 3074 3075 3076 3077 3078 3079 3080 3081 3082 3083 3084 3085 3086 3087 3088 3089 3090 3091 3092 3093 3094 3095 3096 3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135 3136 3137 3138 3139 3140 3141 3142 3143 3144 3145 3146 3147 3148 3149 3150 3151 3152 3153 3154 3155 3156 3157 3158 3159 3160 3161 3162 3163 3164 3165 3166 3167 3168 3169 3170 3171 3172 3173 3174 3175 3176 3177 3178 3179 3180 3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191 3192 3193 3194 3195 3196 3197 3198 3199 3200 3201 3202 3203 3204 3205 3206 3207 3208 3209 3210 3211 3212 3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227 3228 3229 3230 3231 3232 3233 3234 3235 3236 3237 3238 3239 3240 3241 3242 3243 3244 3245 3246 3247 3248 3249 3250 3251 3252 3253 3254 3255 3256 3257 3258 3259 3260 3261 3262 3263 3264 3265 3266 3267 3268 3269 3270 3271 3272 3273 3274 3275 3276 3277 3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288 3289 3290 3291 3292 3293 3294 3295 3296 3297 3298 3299 3300 3301 3302 3303 3304 3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316 3317 3318 3319 3320 3321 3322 3323 3324 3325 3326 3327 3328 3329 3330 3331 3332 3333 3334 3335 3336 3337 3338 3339 3340 3341 3342 3343 3344 3345 3346 3347 3348 3349 3350 3351 3352 3353 3354 3355 3356 3357 3358 3359 3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 3395 3396 3397 3398 3399 3400 3401 3402 3403 3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424 3425 3426 3427 3428 3429 3430 3431 3432 3433 3434 3435 3436 3437 3438 3439 3440 3441 3442 3443 3444 3445 3446 3447 3448 3449 3450 3451 3452 3453 3454 3455 3456 3457 3458 3459 3460 3461 3462 3463 3464 3465 3466 3467 3468 3469 3470 3471 3472 3473 3474 3475 3476 3477 3478 3479 3480 3481 3482 3483 3484 3485 3486 3487 3488 3489 3490 3491 3492 3493 3494 3495 3496 3497 3498 3499 3500 3501 3502 3503 3504 3505 3506 3507 3508 3509 3510 3511 3512 3513 3514 3515 3516 3517 3518 3519 3520 3521 3522 3523 3524 3525 3526 3527 3528 3529 3530 3531 3532 3533 3534 3535 3536 3537 3538 3539 3540 3541 3542 3543 3544 3545 3546 3547 3548 3549 3550 3551 3552 3553 3554 3555 3556 3557 3558 3559 3560 3561 3562 3563 3564 3565 3566 3567 3568 3569 3570 3571 3572 3573 3574 3575 3576 3577 3578 3579 3580 3581 3582 3583 3584 3585 3586 3587 3588 3589 3590 3591 3592 3593 3594 3595 3596 3597 3598 3599 3600 3601 3602 3603 3604 3605 3606 3607 3608 3609 3610 3611 3612 3613 3614 3615 3616 3617 3618 3619 3620 3621 3622 3623 3624 3625 3626 3627 3628 3629 3630 3631 3632 3633 3634 3635 3636 3637 3638 3639 3640 3641 3642 3643 3644 3645 3646 3647 3648 3649 3650 3651 3652 3653 3654 3655 3656 3657 3658 3659 3660 3661 3662 3663 3664 3665 3666 3667 3668 3669 3670 3671 3672 3673 3674 3675 3676 3677 3678 3679 3680 3681 3682 3683 3684 3685 3686 3687 3688 3689 3690 3691 3692 3693 3694 3695 3696 3697 3698 3699 3700 3701 3702 3703 3704 3705 3706 3707 3708 3709 3710 3711 3712 3713 3714 3715 3716 3717 3718 3719 3720 3721 3722 3723 3724 3725 3726 3727 3728 3729 3730 3731 3732 3733 3734 3735 3736 3737 3738 3739 3740 3741 3742 3743 3744 3745 3746 3747 3748 3749 3750 3751 3752 3753 3754 3755 3756 3757 3758 3759 3760 3761 3762 3763 3764 3765 3766 3767 3768 3769 3770 3771 3772 3773 3774 3775 3776 3777 3778 3779 3780 3781 3782 3783 3784 3785 3786 3787 3788 3789 3790 3791 3792 3793 3794 3795 3796 3797 3798 3799 3800 3801 3802 3803 3804 3805 3806 3807 3808 3809 3810 3811 3812 3813 3814 3815 3816 3817 3818 3819 3820 3821 3822 3823 3824 3825 3826 3827 3828 3829 3830 3831 3832 3833 3834 3835 3836 3837 3838 3839 3840 3841 3842 3843 3844 3845 3846 3847 3848 3849 3850 3851 3852 3853 3854 3855 3856 3857 3858 3859 3860 3861 3862 3863 3864 3865 3866 3867 3868 3869 3870 3871 3872 3873 3874 3875 3876 3877 3878 3879 3880 3881 3882 3883 3884 3885 3886 3887 3888 3889 3890 3891 3892 3893 3894 3895 3896 3897 3898 3899 3900 3901 3902 3903 3904 3905 3906 3907 3908 3909 3910 3911 3912 3913 3914 3915 3916 3917 3918 3919 3920 3921 3922 3923 3924 3925 3926 3927 3928 3929 3930 3931 3932 3933 3934 3935 3936 3937 3938 3939 3940 3941 3942 3943 3944 3945 3946 3947 3948 3949 3950 3951 3952 3953 3954 3955 3956 3957 3958 3959 3960 3961 3962 3963 3964 3965 3966 3967 3968 3969 3970 3971 3972 3973 3974 3975 3976 3977 3978 3979 3980 3981 3982 3983 3984 3985 3986 3987 3988 3989 3990 3991 3992 3993 3994 3995 3996 3997 3998 3999 4000 4001 4002 4003 4004 4005 4006 4007 4008 4009 4010 4011 4012 4013 4014 4015 4016 4017 4018 4019 4020 4021 4022 4023 4024 4025 4026 4027 4028 4029 4030 4031 4032 4033 4034 4035 4036 4037 4038 4039 4040 4041 4042 4043 4044 4045 4046 4047 4048 4049 4050 4051 4052 4053 4054 4055 4056 4057 4058 4059 4060 4061 4062 4063 4064 4065 4066 4067 4068 4069 4070 4071 4072 4073 4074 4075 4076 4077 4078 4079 4080 4081 4082 4083 4084 4085 4086 4087 4088 4089 4090 4091 4092 4093 4094 4095 4096 4097 4098 4099 4100 4101 4102 4103 4104 4105 4106 4107 4108 4109 4110 4111 4112 4113 4114 4115 4116 4117 4118 4119 4120 4121 4122 4123 4124 4125 4126 4127 4128 4129 4130 4131 4132 4133 4134 4135 4136 4137 4138 4139 4140 4141 4142 4143 4144 4145 4146 4147 4148 4149 4150 4151 4152 4153 4154 4155 4156 4157 4158 4159 4160 4161 4162 4163 4164 4165 4166 4167 4168 4169 4170 4171 4172 4173 4174 4175 4176 4177 4178 4179 4180 4181 4182 4183 4184 4185 4186 4187 4188 4189 4190 4191 4192 4193 4194 4195 4196 4197 4198 4199 4200 4201 4202 4203 4204 4205 4206 4207 4208 4209 4210 4211 4212 4213 4214 4215 4216 4217 4218 4219 4220 4221 4222 4223 4224 4225 4226 4227 4228 4229 4230 4231 4232 4233 4234 4235 4236 4237 4238 4239 4240 4241 4242 4243 4244 4245 4246 4247 4248 4249 4250 4251 4252 4253 4254 4255 4256 4257 4258 4259 4260 4261 4262 4263 4264 4265 4266 4267 4268 4269 4270 4271 4272 4273 4274 4275 4276 4277 4278 4279 4280 4281 4282 4283 4284 4285 4286 4287 4288 4289 4290 4291 4292 4293 4294 4295 4296 4297 4298 4299 4300 4301 4302 4303 4304 4305 4306 4307 4308 4309 4310 4311 4312 4313 4314 4315 4316 4317 4318 4319 4320 4321 4322 4323 4324 4325 4326 4327 4328 4329 4330 4331 4332 4333 4334 4335 4336 4337 4338 4339 4340 4341 4342 4343 4344 4345 4346 4347 4348 4349 4350 4351 4352 4353 4354 4355 4356 4357 4358 4359 4360 4361 4362 4363 4364 4365 4366 4367 4368 4369 4370 4371 4372 4373 4374 4375 4376 4377 4378 4379 4380 4381 4382 4383 4384 4385 4386 4387 4388 4389 4390 4391 4392 4393 4394 4395 4396 4397 4398 4399 4400 4401 4402 4403 4404 4405 4406 4407 4408 4409 4410 4411 4412 4413 4414 4415 4416 4417 4418 4419 4420 4421 4422 4423 4424 4425 4426 4427 4428 4429 4430 4431 4432 4433 4434 4435 4436 4437 4438 4439 4440 4441 4442 4443 4444 4445 4446 4447 4448 4449 4450 4451 4452 4453 4454 4455 4456 4457 4458 4459 4460 4461 4462 4463 4464 4465 4466 4467 4468 4469 4470 4471 4472 4473 4474 4475 4476 4477 4478 4479 4480 4481 4482 4483 4484 4485 4486 4487 4488 4489 4490 4491 4492 4493 4494 4495 4496 4497 4498 4499 4500 4501 4502 4503 4504 4505 4506 4507 4508 4509 4510 4511 4512 4513 4514 4515 4516 4517 4518 4519 4520 4521 4522 4523 4524 4525 4526 4527 4528 4529 4530 4531 4532 4533 4534 4535 4536 4537 4538 4539 4540 4541 4542 4543 4544 4545 4546 4547 4548 4549 4550 4551 4552 4553 4554 4555 4556 4557 4558 4559 4560 4561 4562 4563 4564 4565 4566 4567 4568 4569 4570 4571 4572 4573 4574 4575 4576 4577 4578 4579 4580 4581 4582 4583 4584 4585 4586 4587 4588 4589 4590 4591 4592 4593 4594 4595 4596 4597 4598 4599 4600 4601 4602 4603 4604 4605 4606 4607 4608 4609 4610 4611 4612 4613 4614 4615 4616 4617 4618 4619 4620 4621 4622 4623 4624 4625 4626 4627 4628 4629 4630 4631 4632 4633 4634 4635 4636 4637 4638 4639 4640 4641 4642 4643 4644 4645 4646 4647 4648 4649 4650 4651 4652 4653 4654 4655 4656 4657 4658 4659 4660 4661 4662 4663 4664 4665 4666 4667 4668 4669 4670 4671 4672 4673 4674 4675 4676 4677 4678 4679 4680 4681 4682 4683 4684 4685 4686 4687 4688 4689 4690 4691 4692 4693 4694 4695 4696 4697 4698 4699 4700 4701 4702 4703 4704 4705 4706 4707 4708 4709 4710 4711 4712 4713 4714 4715 4716 4717 4718 4719 4720 4721 4722 4723 4724 4725 4726 4727 4728 4729 4730 4731 4732 4733 4734 4735 4736 4737 4738 4739 4740 4741 4742 4743 4744 4745 4746 4747 4748 4749 4750 4751 4752 4753 4754 4755 4756 4757 4758 4759 4760 4761 4762 4763 4764 4765 4766 4767 4768 4769 4770 4771 4772 4773 4774 4775 4776 4777 4778 4779 4780 4781 4782 4783 4784 4785 4786 4787 4788 4789 4790 4791 4792 4793 4794 4795 4796 4797 4798 4799 4800 4801 4802 4803 4804 4805 4806 4807 4808 4809 4810 4811 4812 4813 4814 4815 4816 4817 4818 4819 4820 4821 4822 4823 4824 4825 4826 4827 4828 4829 4830 4831 4832 4833 4834 4835 4836 4837 4838 4839 4840 4841 4842 4843 4844 4845 4846 4847 4848 4849 4850 4851 4852 4853 4854 4855 4856 4857 4858 4859 4860 4861 4862 4863 4864 4865 4866 4867 4868 4869 4870 4871 4872 4873 4874 4875 4876 4877 4878 4879 4880 4881 4882 4883 4884 4885 4886 4887 4888 4889 4890 4891 4892 4893 4894 4895 4896 4897 4898 4899 4900 4901 4902 4903 4904 4905 4906 4907 4908 4909 4910 4911 4912 4913 4914 4915 4916 4917 4918 4919 4920 4921 4922 4923 4924 4925 4926 4927 4928 4929 4930 4931 4932 4933 4934 4935 4936 4937 4938 4939 4940 4941 4942 4943 4944 4945 4946 4947 4948 4949 4950 4951 4952 4953 4954 4955 4956 4957 4958 4959 4960 4961 4962 4963 4964 4965 4966 4967 4968 4969 4970 4971 4972 4973 4974 4975 4976 4977 4978 4979 4980 4981 4982 4983 4984 4985 4986 4987 4988 4989 4990 4991 4992 4993 4994 4995 4996 4997 4998 4999 5000 5001 5002 5003 5004 5005 5006 5007 5008 5009 5010 5011 5012 5013 5014 5015 5016 5017 5018 5019 5020 5021 5022 5023 5024 5025 5026 5027 5028 5029 5030 5031 5032 5033 5034 5035 5036 5037 5038 5039 5040 5041 5042 5043 5044 5045 5046 5047 5048 5049 5050 5051 5052 5053 5054 5055 5056 5057 5058 5059 5060 5061 5062 5063 5064 5065 5066 5067 5068 5069 5070 5071 5072 5073 5074 5075 5076 5077 5078 5079 5080 5081 5082 5083 5084 5085 5086 5087 5088 5089 5090 5091 5092 5093 5094 5095 5096 5097 5098 5099 5100 5101 5102 5103 5104 5105 5106 5107 5108 5109 5110 5111 5112 5113 5114 5115 5116 5117 5118 5119 5120 5121 5122 5123 5124 5125 5126 5127 5128 5129 5130 5131 5132 5133 5134 5135 5136 5137 5138 5139 5140 5141 5142 5143 5144 5145 5146 5147 5148 5149 5150 5151 5152 5153 5154 5155 5156 5157 5158 5159 5160 5161 5162 5163 5164 5165 5166 5167 5168 5169 5170 5171 5172 5173 5174 5175 5176 5177 5178 5179 5180 5181 5182 5183 5184 5185 5186 5187 5188 5189 5190 5191 5192 5193 5194 5195 5196 5197 5198 5199 5200 5201 5202 5203 5204 5205 5206 5207 5208 5209 5210 5211 5212 5213 5214 5215 5216 5217 5218 5219 5220 5221 5222 5223 5224 5225 5226 5227 5228 5229 5230 5231 5232 5233 5234 5235 5236 5237 5238 5239 5240 5241 5242 5243 5244 5245 5246 5247 5248 5249 5250 5251 5252 5253 5254 5255 5256 5257 5258 5259 5260 5261 5262 5263 5264 5265 5266 5267 5268 5269 5270 5271 5272 5273 5274 5275 5276 5277 5278 5279 5280 5281 5282 5283 5284 5285 5286 5287 5288 5289 5290 5291 5292 5293 5294 5295 5296 5297 5298 5299 5300 5301 5302 5303 5304 5305 5306 5307 5308 5309 5310 5311 5312 5313 5314 5315 5316 5317 5318 5319 5320 5321 5322 5323 5324 5325 5326 5327 5328 5329 5330 5331 5332 5333 5334 5335 5336 5337 5338 5339 5340 5341 5342 5343 5344 5345 5346 5347 5348 5349 5350 5351 5352 5353 5354 5355 5356 5357 5358 5359 5360 5361 5362 5363 5364 5365 5366 5367 5368 5369 5370 5371 5372 5373 5374 5375 5376 5377 5378 5379 5380 5381 5382 5383 5384 5385 5386 5387 5388 5389 5390 5391 5392 5393 5394 5395 5396 5397 5398 5399 5400 5401 5402 5403 5404 5405 5406 5407 5408 5409 5410 5411 5412 5413 5414 5415 5416 5417 5418 5419 5420 5421 5422 5423 5424 5425 5426 5427 5428 5429 5430 5431 5432 5433 5434 5435 5436 5437 5438 5439 5440 5441 5442 5443 5444 5445 5446 5447 5448 5449 5450 5451 5452 5453 5454 5455 5456 5457 5458 5459 5460 5461 5462 5463 5464 5465 5466 5467 5468 5469 5470 5471 5472 5473 5474 5475 5476 5477 5478 5479 5480 5481 5482 5483 5484 5485 5486 5487 5488 5489 5490 5491 5492 5493 5494 5495 5496 5497 5498 5499 5500 5501 5502 5503 5504 5505 5506 5507 5508 5509 5510 5511 5512 5513 5514 5515 5516 5517 5518 5519 5520 5521 5522 5523 5524 5525 5526 5527 5528 5529 5530 5531 5532 5533 5534 5535 5536 5537 5538 5539 5540 5541 5542 5543 5544 5545 5546 5547 5548 5549 5550 5551 5552 5553 5554 5555 5556 5557 5558 5559 5560 5561 5562 5563 5564 5565 5566 5567 5568 5569 5570 5571 5572 5573 5574 5575 5576 5577 5578 5579 5580 5581 5582 5583 5584 5585 5586 5587 5588 5589 5590 5591 5592 5593 5594 5595 5596 5597 5598 5599 5600 5601 5602 5603 5604 5605 5606 5607 5608 5609 5610 5611 5612 5613 5614 5615 5616 5617 5618 5619 5620 5621 5622 5623 5624 5625 5626 5627 5628 5629 5630 5631 5632 5633 5634 5635 5636 5637 5638 5639 5640 5641 5642 5643 5644 5645 5646 5647 5648 5649 5650 5651 5652 5653 5654 5655 5656 5657 5658 5659 5660 5661 5662 5663 5664 5665 5666 5667 5668 5669 5670 5671 5672 5673 5674 5675 5676 5677 5678 5679 5680 5681 5682 5683 5684 5685 5686 5687 5688 5689 5690 5691 5692 5693 5694 5695 5696 5697 5698 5699 5700 5701 5702 5703 5704 5705 5706 5707 5708 5709 5710 5711 5712 5713 5714 5715 5716 5717 5718 5719 5720 5721 5722 5723 5724 5725 5726 5727 5728 5729 5730 5731 5732 5733 5734 5735 5736 5737 5738 5739 5740 5741 5742 5743 5744 5745 5746 5747 5748 5749 5750 5751 5752 5753 5754 5755 5756 5757 5758 5759 5760 5761 5762 5763 5764 5765 5766 5767 5768 5769 5770 5771 5772 5773 5774 5775 5776 5777 5778 5779 5780 5781 5782 5783 5784 5785 5786 5787 5788 5789 5790 5791 5792 5793 5794 5795 5796 5797 5798 5799 5800 5801 5802 5803 5804 5805 5806 5807 5808 5809 5810 5811 5812 5813 5814 5815 5816 5817 5818 5819 5820 5821 5822 5823 5824 5825 5826 5827 5828 5829 5830 5831 5832 5833 5834 5835 5836 5837 5838 5839 5840 5841 5842 5843 5844 5845 5846 5847 5848 5849 5850 5851 5852 5853 5854 5855 5856 5857 5858 5859 5860 5861 5862 5863 5864 5865 5866 5867 5868 5869 5870 5871 5872 5873 5874 5875 5876 5877 5878 5879 5880 5881 5882 5883 5884 5885 5886 5887 5888 5889 5890 5891 5892 5893 5894 5895 5896 5897 5898 5899 5900 5901 5902 5903 5904 5905 5906 5907 5908 5909 5910 5911 5912 5913 5914 5915 5916 5917 5918 5919 5920 5921 5922 5923 5924 5925 5926 5927 5928 5929 5930 5931 5932 5933 5934 5935 5936 5937 5938 5939 5940 5941 5942 5943 5944 5945 5946 5947 5948 5949 5950 5951 5952 5953 5954 5955 5956 5957 5958 5959 5960 5961 5962 5963 5964 5965 5966 5967 5968 5969 5970 5971 5972 5973 5974 5975 5976 5977 5978 5979 5980 5981 5982 5983 5984 5985 5986 5987 5988 5989 5990 5991 5992 5993 5994 5995 5996 5997 5998 5999 6000 6001 6002 6003 6004 6005 6006 6007 6008 6009 6010 6011 6012 6013 6014 6015 6016 6017 6018 6019 6020 6021 6022 6023 6024 6025 6026 6027 6028 6029 6030 6031 6032 6033 6034 6035 6036 6037 6038 6039 6040 6041 6042 6043 6044 6045 6046 6047 6048 6049 6050 6051 6052 6053 6054 6055 6056 6057 6058 6059 6060 6061 6062 6063 6064 6065 6066 6067 6068 6069 6070 6071 6072 6073 6074 6075 6076 6077 6078 6079 6080 6081 6082 6083 6084 6085 6086 6087 6088 6089 6090 6091 6092 6093 6094 6095 6096 6097 6098 6099 6100 6101 6102 6103 6104 6105 6106 6107 6108 6109 6110 6111 6112 6113 6114 6115 6116 6117 6118 6119 6120 6121 6122 6123 6124 6125 6126 6127 6128 6129 6130 6131 6132 6133 6134 6135 6136 6137 6138 6139 6140 6141 6142 6143 6144 6145 6146 6147 6148 6149 6150 6151 6152 6153 6154 6155 6156 6157 6158 6159 6160 6161 6162 6163 6164 6165 6166 6167 6168 6169 6170 6171 6172 6173 6174 6175 6176 6177 6178 6179 6180 6181 6182 6183 6184 6185 6186 6187 6188 6189 6190 6191 6192 6193 6194 6195 6196 6197 6198 6199 6200 6201 6202 6203 6204 6205 6206 6207 6208 6209 6210 6211 6212 6213 6214 6215 6216 6217 6218 6219 6220 6221 6222 6223 6224 6225 6226 6227 6228 6229 6230 6231 6232 6233 6234 6235 6236 6237 6238 6239 6240 6241 6242 6243 6244 6245 6246 6247 6248 6249 6250 6251 6252 6253 6254 6255 6256 6257 6258 6259 6260 6261 6262 6263 6264 6265 6266 6267 6268 6269 6270 6271 6272 6273 6274 6275 6276 6277 6278 6279 6280 6281 6282 6283 6284 6285 6286 6287 6288 6289 6290 6291 6292 6293 6294 6295 6296 6297 6298 6299 6300 6301 6302 6303 6304 6305 6306 6307 6308 6309 6310 6311 6312 6313 6314 6315 6316 6317 6318 6319 6320 6321 6322 6323 6324 6325 6326 6327 6328 6329 6330 6331 6332 6333 6334 6335 6336 6337 6338 6339 6340 6341 6342 6343 6344 6345 6346 6347 6348 6349 6350 6351 6352 6353 6354 6355 6356 6357 6358 6359 6360 6361 6362 6363 6364 6365 6366 6367 6368 6369 6370 6371 6372 6373 6374 6375 6376 6377 6378 6379 6380 6381 6382 6383 6384 6385 6386 6387 6388 6389 6390 6391 6392 6393 6394 6395 6396 6397 6398 6399 6400 6401 6402 6403 6404 6405 6406 6407 6408 6409 6410 6411 6412 6413 6414 6415 6416 6417 6418 6419 6420 6421 6422 6423 6424 6425 6426 6427 6428 6429 6430 6431 6432 6433 6434 6435 6436 6437 6438 6439 6440 6441 6442 6443 6444 6445 6446 6447 6448 6449 6450 6451 6452 6453 6454 6455 6456 6457 6458 6459 6460 6461 6462 6463 6464 6465 6466 6467 6468 6469 6470 6471 6472 6473 6474 6475 6476 6477 6478 6479 6480 6481 6482 6483 6484 6485 6486 6487 6488 6489 6490 6491 6492 6493 6494 6495 6496 6497 6498 6499 6500 6501 6502 6503 6504 6505 6506 6507 6508 6509 6510 6511 6512 6513 6514 6515 6516 6517 6518 6519 6520 6521 6522 6523 6524 6525 6526 6527 6528 6529 6530 6531 6532 6533 6534 6535 6536 6537 6538 6539 6540 6541 6542 6543 6544 6545 6546 6547 6548 6549 6550 6551 6552 6553 6554 6555 6556 6557 6558 6559 6560 6561 6562 6563 6564 6565 6566 6567 6568 6569 6570 6571 6572 6573 6574 6575 6576 6577 6578 6579 6580 6581 6582 6583 6584 6585 6586 6587 6588 6589 6590 6591 6592 6593 6594 6595 6596 6597 6598 6599 6600 6601 6602 6603 6604 6605 6606 6607 6608 6609 6610 6611 6612 6613 6614 6615 6616 6617 6618 6619 6620 6621 6622 6623 6624 6625 6626 6627 6628 6629 6630 6631 6632 6633 6634 6635 6636 6637 6638 6639 6640 6641 6642 6643 6644 6645 6646 6647 6648 6649 6650 6651 6652 6653 6654 6655 6656 6657 6658 6659 6660 6661 6662 6663 6664 6665 6666 6667 6668 6669 6670 6671 6672 6673 6674 6675 6676 6677 6678 6679 6680 6681 6682 6683 6684 6685 6686 6687 6688 6689 6690 6691 6692 6693 6694 6695 6696 6697 6698 6699 6700 6701 6702 6703 6704 6705 6706 6707 6708 6709 6710 6711 6712 6713 6714 6715 6716 6717 6718 6719 6720 6721 6722 6723 6724 6725 6726 6727 6728 6729 6730 6731 6732 6733 6734 6735 6736 6737 6738 6739 6740 6741 6742 6743 6744 6745 6746 6747 6748 6749 6750 6751 6752 6753 6754 6755 6756 6757 6758 6759 6760 6761 6762 6763 6764 6765 6766 6767 6768 6769 6770 6771 6772 6773 6774 6775 6776 6777 6778 6779 6780 6781 6782 6783 6784 6785 6786 6787 6788 6789 6790 6791 6792 6793 6794 6795 6796 6797 6798 6799 6800 6801 6802 6803 6804 6805 6806 6807 6808 6809 6810 6811 6812 6813 6814 6815 6816 6817 6818 6819 6820 6821 6822 6823 6824 6825 6826 6827 6828 6829 6830 6831 6832 6833 6834 6835 6836 6837 6838 6839 6840 6841 6842 6843 6844 6845 6846 6847 6848 6849 6850 6851 6852 6853 6854 6855 6856 6857 6858 6859 6860 6861 6862 6863 6864 6865 6866 6867 6868 6869 6870 6871 6872 6873 6874 6875 6876 6877 6878 6879 6880 6881 6882 6883 6884 6885 6886 6887 6888 6889 6890 6891 6892 6893 6894 6895 6896 6897 6898 6899 6900 6901 6902 6903 6904 6905 6906 6907 6908 6909 6910 6911 6912 6913 6914 6915 6916 6917 6918 6919 6920 6921 6922 6923 6924 6925 6926 6927 6928 6929 6930 6931 6932 6933 6934 6935 6936 6937 6938 6939 6940 6941 6942 6943 6944 6945 6946 6947 6948 6949 6950 6951 6952 6953 6954 6955 6956 6957 6958 6959 6960 6961 6962 6963 6964 6965 6966 6967 6968 6969 6970 6971 6972 6973 6974 6975 6976 6977 6978 6979 6980 6981 6982 6983 6984 6985 6986 6987 6988 6989 6990 6991 6992 6993 6994 6995 6996 6997 6998 6999 7000 7001 7002 7003 7004 7005 7006 7007 7008 7009 7010 7011 7012 7013 7014 7015 7016 7017 7018 7019 7020 7021 7022 7023 7024 7025 7026 7027 7028 7029 7030 7031 7032 7033 7034 7035 7036 7037 7038 7039 7040 7041 7042 7043 7044 7045 7046 7047 7048 7049 7050 7051 7052 7053 7054 7055 7056 7057 7058 7059 7060 7061 7062 7063 7064 7065 7066 7067 7068 7069 7070 7071 7072 7073 7074 7075 7076 7077 7078 7079 7080 7081 7082 7083 7084 7085 7086 7087 7088 7089 7090 7091 7092 7093 7094 7095 7096 7097 7098 7099 7100 7101 7102 7103 7104 7105 7106 7107 7108 7109 7110 7111 7112 7113 7114 7115 7116 7117 7118 7119 7120 7121 7122 7123 7124 7125 7126 7127 7128 7129 7130 7131 7132 7133 7134 7135 7136 7137 7138 7139 7140 7141 7142 7143 7144 7145 7146 7147 7148 7149 7150 7151 7152 7153 7154 7155 7156 7157 7158 7159 7160 7161 7162 7163 7164 7165 7166 7167 7168 7169 7170 7171 7172 7173 7174 7175 7176 7177 7178 7179 7180 7181 7182 7183 7184 7185 7186 7187 7188 7189 7190 7191 7192 7193 7194 7195 7196 7197 7198 7199 7200 7201 7202 7203 7204 7205 7206 7207 7208 7209 7210 7211 7212 7213 7214 7215 7216 7217 7218 7219 7220 7221 7222 7223 7224 7225 7226 7227 7228 7229 7230 7231 7232 7233 7234 7235 7236 7237 7238 7239 7240 7241 7242 7243 7244 7245 7246 7247 7248 7249 7250 7251 7252 7253 7254 7255 7256 7257 7258 7259 7260 7261 7262 7263 7264 7265 7266 7267 7268 7269 7270 7271 7272 7273 7274 7275 7276 7277 7278 7279 7280 7281 7282 7283 7284 7285 7286 7287 7288 7289 7290 7291 7292 7293 7294 7295 7296 7297 7298 7299 7300 7301 7302 7303 7304 7305 7306 7307 7308 7309 7310 7311 7312 7313 7314 7315 7316 7317 7318 7319 7320 7321 7322 7323 7324 7325 7326 7327 7328 7329 7330 7331 7332 7333 7334 7335 7336 7337 7338 7339 7340 7341 7342 7343 7344 7345 7346 7347 7348 7349 7350 7351 7352 7353 7354 7355 7356 7357 7358 7359 7360 7361 7362 7363 7364 7365 7366 7367 7368 7369 7370 7371 7372 7373 7374 7375 7376 7377 7378 7379 7380 7381 7382 7383 7384 7385 7386 7387 7388 7389 7390 7391 7392 7393 7394 7395 7396 7397 7398 7399 7400 7401 7402 7403 7404 7405 7406 7407 7408 7409 7410 7411 7412 7413 7414 7415 7416 7417 7418 7419 7420 7421 7422 7423 7424 7425 7426 7427 7428 7429 7430 7431 7432 7433 7434 7435 7436 7437 7438 7439 7440 7441 7442 7443 7444 7445 7446 7447 7448 7449 7450 7451 7452 7453 7454 7455 7456 7457 7458 7459 7460 7461 7462 7463 7464 7465 7466 7467 7468 7469 7470 7471 7472 7473 7474 7475 7476 7477 7478 7479 7480 7481 7482 7483 7484 7485 7486 7487 7488 7489 7490 7491 7492 7493 7494 7495 7496 7497 7498 7499 7500 7501 7502 7503 7504 7505 7506 7507 7508 7509 7510 7511 7512 7513 7514 7515 7516 7517 7518 7519 7520 7521 7522 7523 7524 7525 7526 7527 7528 7529 7530 7531 7532 7533 7534 7535 7536 7537 7538 7539 7540 7541 7542 7543 7544 7545 7546 7547 7548 7549 7550 7551 7552 7553 7554 7555 7556 7557 7558 7559 7560 7561 7562 7563 7564 7565 7566 7567 7568 7569 7570 7571 7572 7573 7574 7575 7576 7577 7578 7579 7580 7581 7582 7583 7584 7585 7586 7587 7588 7589 7590 7591 7592 7593 7594 7595 7596 7597 7598 7599 7600 7601 7602 7603 7604 7605 7606 7607 7608 7609 7610 7611 7612 7613 7614 7615 7616 7617 7618 7619 7620 7621 7622 7623 7624 7625 7626 7627 7628 7629 7630 7631 7632 7633 7634 7635 7636 7637 7638 7639 7640 7641 7642 7643 7644 7645 7646 7647 7648 7649 7650 7651 7652 7653 7654 7655 7656 7657 7658 7659 7660 7661 7662 7663 7664 7665 7666 7667 7668 7669 7670 7671 7672 7673 7674 7675 7676 7677 7678 7679 7680 7681 7682 7683 7684 7685 7686 7687 7688 7689 7690 7691 7692 7693 7694 7695 7696 7697 7698 7699 7700 7701 7702 7703 7704 7705 7706 7707 7708 7709 7710 7711 7712 7713 7714 7715 7716 7717 7718 7719 7720 7721 7722 7723 7724 7725 7726 7727 7728 7729 7730 7731 7732 7733 7734 7735 7736 7737 7738 7739 7740 7741 7742 7743 7744 7745 7746 7747 7748 7749 7750 7751 7752 7753 7754 7755 7756 7757 7758 7759 7760 7761 7762 7763 7764 7765 7766 7767 7768 7769 7770 7771 7772 7773 7774 7775 7776 7777 7778 7779 7780 7781 7782 7783 7784 7785 7786 7787 7788 7789 7790 7791 7792 7793 7794 7795 7796 7797 7798 7799 7800 7801 7802 7803 7804 7805 7806 7807 7808 7809 7810 7811 7812 7813 7814 7815 7816 7817 7818 7819 7820 7821 7822 7823 7824 7825 7826 7827 7828 7829 7830 7831 7832 7833 7834 7835 7836 7837 7838 7839 7840 7841 7842 7843 7844 7845 7846 7847 7848 7849 7850 7851 7852 7853 7854 7855 7856 7857 7858 7859 7860 7861 7862 7863 7864 7865 7866 7867 7868 7869 7870 7871 7872 7873 7874 7875 7876 7877 7878 7879 7880 7881 7882 7883 7884 7885 7886 7887 7888 7889 7890 7891 7892 7893 7894 7895 7896 7897 7898 7899 7900 7901 7902 7903 7904 7905 7906 7907 7908 7909 7910 7911 7912 7913 7914 7915 7916 7917 7918 7919 7920 7921 7922 7923 7924 7925 7926 7927 7928 7929 7930 7931 7932 7933 7934 7935 7936 7937 7938 7939 7940 7941 7942 7943 7944 7945 7946 7947 7948 7949 7950 7951 7952 7953 7954 7955 7956 7957 7958 7959 7960 7961 7962 7963 7964 7965 7966 7967 7968 7969 7970 7971 7972 7973 7974 7975 7976 7977 7978 7979 7980 7981 7982 7983 7984 7985 7986 7987 7988 7989 7990 7991 7992 7993 7994 7995 7996 7997 7998 7999 8000 8001 8002 8003 8004 8005 8006 8007 8008 8009 8010 8011 8012 8013 8014 8015 8016 8017 8018 8019 8020 8021 8022 8023 8024 8025 8026 8027 8028 8029 8030 8031 8032 8033 8034 8035 8036 8037 8038 8039 8040 8041 8042 8043 8044 8045 8046 8047 8048 8049 8050 8051 8052 8053 8054 8055 8056 8057 8058 8059 8060 8061 8062 8063 8064 8065 8066 8067 8068 8069 8070 8071 8072 8073 8074 8075 8076 8077 8078 8079 8080 8081 8082 8083 8084 8085 8086 8087 8088 8089 8090 8091 8092 8093 8094 8095 8096 8097 8098 8099 8100 8101 8102 8103 8104 8105 8106 8107 8108 8109 8110 8111 8112 8113 8114 8115 8116 8117 8118 8119 8120 8121 8122 8123 8124 8125 8126 8127 8128 8129 8130 8131 8132 8133 8134 8135 8136 8137 8138 8139 8140 8141 8142 8143 8144 8145 8146 8147 8148 8149 8150 8151 8152 8153 8154 8155 8156 8157 8158 8159 8160 8161 8162 8163 8164 8165 8166 8167 8168 8169 8170 8171 8172 8173 8174 8175 8176 8177 8178 8179 8180 8181 8182 8183 8184 8185 8186 8187 8188 8189 8190 8191 8192 8193 8194 8195 8196 8197 8198 8199 8200 8201 8202 8203 8204 8205 8206 8207 8208 8209 8210 8211 8212 8213 8214 8215 8216 8217 8218 8219 8220 8221 8222 8223 8224 8225 8226 8227 8228 8229 8230 8231 8232 8233 8234 8235 8236 8237 8238 8239 8240 8241 8242 8243 8244 8245 8246 8247 8248 8249 8250 8251 8252 8253 8254 8255 8256 8257 8258 8259 8260 8261 8262 8263 8264 8265 8266 8267 8268 8269 8270 8271 8272 8273 8274 8275 8276 8277 8278 8279 8280 8281 8282 8283 8284 8285 8286 8287 8288 8289 8290 8291 8292 8293 8294 8295 8296 8297 8298 8299 8300 8301 8302 8303 8304 8305 8306 8307 8308 8309 8310 8311 8312 8313 8314 8315 8316 8317 8318 8319 8320 8321 8322 8323 8324 8325 8326 8327 8328 8329 8330 8331 8332 8333 8334 8335 8336 8337 8338 8339 8340 8341 8342 8343 8344 8345 8346 8347 8348 8349 8350 8351 8352 8353 8354 8355 8356 8357 8358 8359 8360 8361 8362 8363 8364 8365 8366 8367 8368 8369 8370 8371 8372 8373 8374 8375 8376 8377 8378 8379 8380 8381 8382 8383 8384 8385 8386 8387 8388 8389 8390 8391 8392 8393 8394 8395 8396 8397 8398 8399 8400 8401 8402 8403 8404 8405 8406 8407 8408 8409 8410 8411 8412 8413 8414 8415 8416 8417 8418 8419 8420 8421 8422 8423 8424 8425 8426 8427 8428 8429 8430 8431 8432 8433 8434 8435 8436 8437 8438 8439 8440 8441 8442 8443 8444 8445 8446 8447 8448 8449 8450 8451 8452 8453 8454 8455 8456 8457 8458 8459 8460 8461 8462 8463 8464 8465 8466 8467 8468 8469 8470 8471 8472 8473 8474 8475 8476 8477 8478 8479 8480 8481 8482 8483 8484 8485 8486 8487 8488 8489 8490 8491 8492 8493 8494 8495 8496 8497 8498 8499 8500 8501 8502 8503 8504 8505 8506 8507 8508 8509 8510 8511 8512 8513 8514 8515 8516 8517 8518 8519 8520 8521 8522 8523 8524 8525 8526 8527 8528 8529 8530 8531 8532 8533 8534 8535 8536 8537 8538 8539 8540 8541 8542 8543 8544 8545 8546 8547 8548 8549 8550 8551 8552 8553 8554 8555 8556 8557 8558 8559 8560 8561 8562 8563 8564 8565 8566 8567 8568 8569 8570 8571 8572 8573 8574 8575 8576 8577 8578 8579 8580 8581 8582 8583 8584 8585 8586 8587 8588 8589 8590 8591 8592 8593 8594 8595 8596 8597 8598 8599 8600 8601 8602 8603 8604 8605 8606 8607 8608 8609 8610 8611 8612 8613 8614 8615 8616 8617 8618 8619 8620 8621 8622 8623 8624 8625 8626 8627 8628 8629 8630 8631 8632 8633 8634 8635 8636 8637 8638 8639 8640 8641 8642 8643 8644 8645 8646 8647 8648 8649 8650 8651 8652 8653 8654 8655 8656 8657 8658 8659 8660 8661 8662 8663 8664 8665 8666 8667 8668 8669 8670 8671 8672 8673 8674 8675 8676 8677 8678 8679 8680 8681 8682 8683 8684 8685 8686 8687 8688 8689 8690 8691 8692 8693 8694 8695 8696 8697 8698 8699 8700 8701 8702 8703 8704 8705 8706 8707 8708 8709 8710 8711 8712 8713 8714 8715 8716 8717 8718 8719 8720 8721 8722 8723 8724 8725 8726 8727 8728 8729 8730 8731 8732 8733 8734 8735 8736 8737 8738 8739 8740 8741 8742 8743 8744 8745 8746 8747 8748 8749 8750 8751 8752 8753 8754 8755 8756 8757 8758 8759 8760 8761 8762 8763 8764 8765 8766 8767 8768 8769 8770 8771 8772 8773 8774 8775 8776 8777 8778 8779 8780 8781 8782 8783 8784 8785 8786 8787 8788 8789 8790 8791 8792 8793 8794 8795 8796 8797 8798 8799 8800 8801 8802 8803 8804 8805 8806 8807 8808 8809 8810 8811 8812 8813 8814 8815 8816 8817 8818 8819 8820 8821 8822 8823 8824 8825 8826 8827 8828 8829 8830 8831 8832 8833 8834 8835 8836 8837 8838 8839 8840 8841 8842 8843 8844 8845 8846 8847 8848 8849 8850 8851 8852 8853 8854 8855 8856 8857 8858 8859 8860 8861 8862 8863 8864 8865 8866 8867 8868 8869 8870 8871 8872 8873 8874 8875 8876 8877 8878 8879 8880 8881 8882 8883 8884 8885 8886 8887 8888 8889 8890 8891 8892 8893 8894 8895 8896 8897 8898 8899 8900 8901 8902 8903 8904 8905 8906 8907 8908 8909 8910 8911 8912 8913 8914 8915 8916 8917 8918 8919 8920 8921 8922 8923 8924 8925 8926 8927 8928 8929 8930 8931 8932 8933 8934 8935 8936 8937 8938 8939 8940 8941 8942 8943 8944 8945 8946 8947 8948 8949 8950 8951 8952 8953 8954 8955 8956 8957 8958 8959 8960 8961 8962 8963 8964 8965 8966 8967 8968 8969 8970 8971 8972 8973 8974 8975 8976 8977 8978 8979 8980 8981 8982 8983 8984 8985 8986 8987 8988 8989 8990 8991 8992 8993 8994 8995 8996 8997 8998 8999 9000 9001 9002 9003 9004 9005 9006 9007 9008 9009 9010 9011 9012 9013 9014 9015 9016 9017 9018 9019 9020 9021 9022 9023 9024 9025 9026 9027 9028 9029 9030 9031 9032 9033 9034 9035 9036 9037 9038 9039 9040 9041 9042 9043 9044 9045 9046 9047 9048 9049 9050 9051 9052 9053 9054 9055 9056 9057 9058 9059 9060 9061 9062 9063 9064 9065 9066 9067 9068 9069 9070 9071 9072 9073 9074 9075 9076 9077 9078 9079 9080 9081 9082 9083 9084 9085 9086 9087 9088 9089 9090 9091 9092 9093 9094 9095 9096 9097 9098 9099 9100 9101 9102 9103 9104 9105 9106 9107 9108 9109 9110 9111 9112 9113 9114 9115 9116 9117 9118 9119 9120 9121 9122 9123 9124 9125 9126 9127 9128 9129 9130 9131 9132 9133 9134 9135 9136 9137 9138 9139 9140 9141 9142 9143 9144 9145 9146 9147 9148 9149 9150 9151 9152 9153 9154 9155 9156 9157 9158 9159 9160 9161 9162 9163 9164 9165 9166 9167 9168 9169 9170 9171 9172 9173 9174 9175 9176 9177 9178 9179 9180 9181 9182 9183 9184 9185 9186 9187 9188 9189 9190 9191 9192 9193 9194 9195 9196 9197 9198 9199 9200 9201 9202 9203 9204 9205 9206 9207 9208 9209 9210 9211 9212 9213 9214 9215 9216 9217 9218 9219 9220 9221 9222 9223 9224 9225 9226 9227 9228 9229 9230 9231 9232 9233 9234 9235 9236 9237 9238 9239 9240 9241 9242 9243 9244 9245 9246 9247 9248 9249 9250 9251 9252 9253 9254 9255 9256 9257 9258 9259 9260 9261 9262 9263 9264 9265 9266 9267 9268 9269 9270 9271 9272 9273 9274 9275 9276 9277 9278 9279 9280 9281 9282 9283 9284 9285 9286 9287 9288 9289 9290 9291 9292 9293 9294 9295 9296 9297 9298 9299 9300 9301 9302 9303 9304 9305 9306 9307 9308 9309 9310 9311 9312 9313 9314 9315 9316 9317 9318 9319 9320 9321 9322 9323 9324 9325 9326 9327 9328 9329 9330 9331 9332 9333 9334 9335 9336 9337 9338 9339 9340 9341 9342 9343 9344 9345 9346 9347 9348 9349 9350 9351 9352 9353 9354 9355 9356 9357 9358 9359 9360 9361 9362 9363 9364 9365 9366 9367 9368 9369 9370 9371 9372 9373 9374 9375 9376 9377 9378 9379 9380 9381 9382 9383 9384 9385 9386 9387 9388 9389 9390 9391 9392 9393 9394 9395 9396 9397 9398 9399 9400 9401 9402 9403 9404 9405 9406 9407 9408 9409 9410 9411 9412 9413 9414 9415 9416 9417 9418 9419 9420 9421 9422 9423 9424 9425 9426 9427 9428 9429 9430 9431 9432 9433 9434 9435 9436 9437 9438 9439 9440 9441 9442 9443 9444 9445 9446 9447 9448 9449 9450 9451 9452 9453 9454 9455 9456 9457 9458 9459 9460 9461 9462 9463 9464 9465 9466 9467 9468 9469 9470 9471 9472 9473 9474 9475 9476 9477 9478 9479 9480 9481 9482 9483 9484 9485 9486 9487 9488 9489 9490 9491 9492 9493 9494 9495 9496 9497 9498 9499 9500 9501 9502 9503 9504 9505 9506 9507 9508 9509 9510 9511 9512 9513 9514 9515 9516 9517 9518 9519 9520 9521 9522 9523 9524 9525 9526 9527 9528 9529 9530 9531 9532 9533 9534 9535 9536 9537 9538 9539 9540 9541 9542 9543 9544 9545 9546 9547 9548 9549 9550 9551 9552 9553 9554 9555 9556 9557 9558 9559 9560 9561 9562 9563 9564 9565 9566 9567 9568 9569 9570 9571 9572 9573 9574 9575 9576 9577 9578 9579 9580 9581 9582 9583 9584 9585 9586 9587 9588 9589 9590 9591 9592 9593 9594 9595 9596 9597 9598 9599 9600 9601 9602 9603 9604 9605 9606 9607 9608 9609 9610 9611 9612 9613 9614 9615 9616 9617 9618 9619 9620 9621 9622 9623 9624 9625 9626 9627 9628 9629 9630 9631 9632 9633 9634 9635 9636 9637 9638 9639 9640 9641 9642 9643 9644 9645 9646 9647 9648 9649 9650 9651 9652 9653 9654 9655 9656 9657 9658 9659 9660 9661 9662 9663 9664 9665 9666 9667 9668 9669 9670 9671 9672 9673 9674 9675 9676 9677 9678 9679 9680 9681 9682 9683 9684 9685 9686 9687 9688 9689 9690 9691 9692 9693 9694 9695 9696 9697 9698 9699 9700 9701 9702 9703 9704 9705 9706 9707 9708 9709 9710 9711 9712 9713 9714 9715 9716 9717 9718 9719 9720 9721 9722 9723 9724 9725 9726 9727 9728 9729 9730 9731 9732 9733 9734 9735 9736 9737 9738 9739 9740 9741 9742 9743 9744 9745 9746 9747 9748 9749 9750 9751 9752 9753 9754 9755 9756 9757 9758 9759 9760 9761 9762 9763 9764 9765 9766 9767 9768 9769 9770 9771 9772 9773 9774 9775 9776 9777 9778 9779 9780 9781 9782 9783 9784 9785 9786 9787 9788 9789 9790 9791 9792 9793 9794 9795 9796 9797 9798 9799 9800 9801 9802 9803 9804 9805 9806 9807 9808 9809 9810 9811 9812 9813 9814 9815 9816 9817 9818 9819 9820 9821 9822 9823 9824 9825 9826 9827 9828 9829 9830 9831 9832 9833 9834 9835 9836 9837 9838 9839 9840 9841 9842 9843 9844 9845 9846 9847 9848 9849 9850 9851 9852 9853 9854 9855 9856 9857 9858 9859 9860 9861 9862 9863 9864 9865 9866 9867 9868 9869 9870 9871 9872 9873 9874 9875 9876 9877 9878 9879 9880 9881 9882 9883 9884 9885 9886 9887 9888 9889 9890 9891 9892 9893 9894 9895 9896 9897 9898 9899 9900 9901 9902 9903 9904 9905 9906 9907 9908 9909 9910 9911 9912 9913 9914 9915 9916 9917 9918 9919 9920 9921 9922 9923 9924 9925 9926 9927 9928 9929 9930 9931 9932 9933 9934 9935 9936 9937 9938 9939 9940 9941 9942 9943 9944 9945 9946 9947 9948 9949 9950 9951 9952 9953 9954 9955 9956 9957 9958 9959 9960 9961 9962 9963 9964 9965 9966 9967 9968 9969 9970 9971 9972 9973 9974 9975 9976 9977 9978 9979 9980 9981 9982 9983 9984 9985 9986 9987 9988 9989 9990 9991 9992 9993 9994 9995 9996 9997 9998 9999 10000 10001 10002 10003 10004 10005 10006 10007 10008 10009 10010 10011 10012 10013 10014 10015 10016
<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
                  "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
<article>
  <articleinfo>
    <title></title>
  </articleinfo>
<sect1 id="prelude">
  <title>Prelude</title>
  <para>
    Welcome to my (in-progress) book about the
    <ulink url="http://documentcloud.github.com/backbone/">Backbone.js</ulink>
    framework for structuring JavaScript applications. It’s released
    under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0
    Unported
    <ulink url="http://creativecommons.org/licenses/by-nc-sa/3.0/">license</ulink>
    meaning you can both grab a copy of the book for free or help to
    further
    <ulink url="https://github.com/addyosmani/backbone-fundamentals/">improve</ulink>
    it.
  </para>
  <para>
    I’m very pleased to announce that this book will be out in physical
    form in a few months time via
    <ulink url="http://oreilly.com">O’Reilly Media</ulink>. Readers will
    have the option of purchasing the latest version in either print or
    a number of digital formats then or can grab a recent version from
    this repository.
  </para>
  <para>
    Corrections to existing material are always welcome and I hope that
    together we can provide the community with an up-to-date resource
    that is of help. My extended thanks go out to
    <ulink url="https://github.com/jashkenas">Jeremy Ashkenas</ulink>
    for creating Backbone.js and
    <ulink url="https://github.com/addyosmani/backbone-fundamentals/contributors">these</ulink>
    members of the community for their assistance tweaking this project.
  </para>
  <para>
    I hope you find this book helpful!
  </para>
</sect1>
<sect1 id="table-of-contents">
  <title>Table Of Contents</title>
  <itemizedlist>
    <listitem>
    </listitem>
    <listitem>
      <itemizedlist>
        <listitem>
          <para>
            <link linkend="mvc-mvp">MVC, MVP &amp; Backbone.js</link>
          </para>
        </listitem>
      </itemizedlist>
    </listitem>
    <listitem>
      <itemizedlist>
        <listitem>
          <para>
            <link linkend="models">Models</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="views">Views</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="collections">Collections</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="routers">Routers</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="namespacing">Namespacing</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="additional-tips">Additional tips</link>
          </para>
        </listitem>
      </itemizedlist>
    </listitem>
    <listitem>
      <itemizedlist>
        <listitem>
          <para>
            <link linkend="restful">Building RESTful applications with
            Backbone</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="stack1">Building Backbone apps with Node.js,
            Express, Mongoose and MongoDB</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="stack2">Building Backbone apps with Ruby,
            Sinatra, Haml and MongoDB</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="pagination">Paginating Backbone.js Requests
            &amp; Collections</link>
          </para>
        </listitem>
      </itemizedlist>
    </listitem>
    <listitem>
      <itemizedlist>
        <listitem>
          <para>
            <link linkend="modularjs">Modular JavaScript</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="organizingmodules">Organizing modules with
            RequireJS and AMD</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="externaltemplates">Keeping your templates
            external with the RequireJS text plugin</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="optimizingrequirejs">Optimizing Backbone apps
            for production with the RequireJS Optimizer</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="practicalrequirejs">Practical: Building a
            modular Backbone app with AMD &amp; RequireJS</link>
          </para>
        </listitem>
        <listitem>
          <para>
            <link linkend="decouplingbackbone">Decoupling Backbone with
            the Mediator and Facade patterns</link>
          </para>
        </listitem>
        <listitem>
          <para>
            Backbone &amp; jQuery Mobile
          </para>
        </listitem>
        <listitem>
          <para>
            Practical: Building A Modular Mobile App With Backbone &amp;
            jQuery Mobile
          </para>
        </listitem>
      </itemizedlist>
    </listitem>
    <listitem>
      <itemizedlist>
        <listitem>
          <para>
            <link linkend="unittestingjasmine">Unit Testing Backbone
            Applications With Jasmine</link>
          </para>
        </listitem>
        <listitem>
          <para>
            Introduction
          </para>
        </listitem>
        <listitem>
          <para>
            Jasmine
          </para>
          <itemizedlist>
            <listitem>
              <para>
                Suites, Specs And Spies
              </para>
            </listitem>
            <listitem>
              <para>
                TDD With Backbone
              </para>
            </listitem>
            <listitem>
              <para>
                <link linkend="testing-jasmine-models">Testing
                Models</link>
              </para>
            </listitem>
            <listitem>
              <para>
                <link linkend="testing-jasmine-collections">Testing
                Collections</link>
              </para>
            </listitem>
            <listitem>
              <para>
                <link linkend="testing-jasmine-views">Testing
                Views</link>
              </para>
            </listitem>
          </itemizedlist>
        </listitem>
        <listitem>
          <para>
            <link linkend="unittestingqunit">Unit Testing Backbone
            Applications With QUnit And SinonJS</link>
          </para>
        </listitem>
        <listitem>
          <para>
            Introduction
          </para>
        </listitem>
        <listitem>
          <para>
            QUnit
          </para>
          <itemizedlist>
            <listitem>
              <para>
                Assertions
              </para>
            </listitem>
            <listitem>
              <para>
                Adding structure to assertions
              </para>
            </listitem>
            <listitem>
              <para>
                Assertion examples
              </para>
            </listitem>
            <listitem>
              <para>
                Fixtures
              </para>
            </listitem>
            <listitem>
              <para>
                Asynchronous code
              </para>
            </listitem>
          </itemizedlist>
        </listitem>
        <listitem>
          <para>
            SinonJS
          </para>
          <itemizedlist>
            <listitem>
              <para>
                Stubs
              </para>
            </listitem>
            <listitem>
              <para>
                Mocks
              </para>
            </listitem>
          </itemizedlist>
        </listitem>
        <listitem>
          <para>
            Practical
          </para>
          <itemizedlist>
            <listitem>
              <para>
                Testing Models
              </para>
            </listitem>
            <listitem>
              <para>
                Testing Collections
              </para>
            </listitem>
            <listitem>
              <para>
                Testing Views
              </para>
            </listitem>
            <listitem>
              <para>
                Testing Events
              </para>
            </listitem>
          </itemizedlist>
        </listitem>
      </itemizedlist>
    </listitem>
    <listitem>
    </listitem>
  </itemizedlist>
</sect1>
<sect1 id="introduction">
  <title><a name="introduction">Introduction</a></title>
  <para>
    As JavaScript developers, we are at an interesting point in time
    where not only do we have mature solutions to help organize the
    JavaScript powering our applications based on a separation of
    concerns, but developers looking to build non-trivial projects are
    almost spoiled for choice for frameworks that can help structure
    their applications.
  </para>
  <para>
    Maturity in software (framework) development isn’t simply about how
    long a framework has been around. It’s about how solid the framework
    is and more importantly how well it’s evolved to fill its role. Has
    it become more effective at solving common problems? Does it
    continue to improve as developers build larger and more complex
    applications with it?
  </para>
  <para>
    In this book, I will be covering the popular Backbone.js, which I
    consider the best of the current family of JavaScript architectural
    frameworks.
  </para>
  <para>
    Topics will include MVC theory and how to build applications using
    Backbone’s models, views, collections and routers. I’ll also be
    taking you through advanced topics like modular development with
    Backbone.js and AMD (via RequireJS), how to build applications using
    modern software stacks (like Node and Express), how to solve the
    routing problems with Backbone and jQuery Mobile, tips about
    scaffolding tools, and a lot more.
  </para>
  <para>
    If this is your first time looking at Backbone.js and you’re still
    unsure whether or not to give it a try, why not take a look at how
    <ulink url="http://github.com/addyosmani/todomvc">a Todo
    application</ulink> can be implemented in Backbone and several other
    popular Javascript frameworks before reading further?
  </para>
  <para>
    The goal of this book is to create an authoritative and centralized
    repository of information that can help those developing real-world
    apps with Backbone. If you come across a section or topic which you
    think could be improved or expanded on, please feel free to submit a
    pull-request. It won’t take long and you’ll be helping other
    developers avoid problems you’ve run into before.
  </para>
</sect1>
<sect1 id="fundamentals">
  <title><a name="fundamentals">Fundamentals</a></title>
  <para>
    In this section we are going to cover the context into which a
    framework like Backbone.js fits. Let’s begin our journey into
    understanding Backbone better with a look at code architecture.
  </para>
  <sect2 id="mvc-mvp-backbone.js">
    <title><a name="mvc-mvp">MVC, MVP &amp; Backbone.js</a></title>
    <para>
      Before exploring any JavaScript frameworks that assist in
      structuring applications, it can be useful to gain a basic
      understanding of architectural design patterns. Design patterns
      are proven solutions to common development problems and can
      suggest structural approaches to help guide developers in adding
      some organization to their applications.
    </para>
    <para>
      Patterns are useful because they’re a set of practices that build
      upon the collective experience of skilled developers who have
      repeatedly solved similar problems. Although developers 10 or 20
      years ago may not have been using the same programming languages
      when implementing patterns in their projects, there are many
      lessons we can learn from their efforts.
    </para>
    <para>
      In this section, we’re going to review two popular patterns - MVC
      and MVP. We’ll be exploring in greater detail how Backbone.js
      implements these patterns shortly to better appreciate where it
      fits in.
    </para>
  </sect2>
</sect1>
<sect1 id="mvc">
  <title>MVC</title>
  <para>
    MVC (Model-View-Controller) is an architectural design pattern that
    encourages improved application organization through a separation of
    concerns. It enforces the isolation of business data (Models) from
    user interfaces (Views), with a third component (Controllers)
    traditionally present to manage logic, user-input and the
    coordination of models and views. The pattern was originally
    designed by
    <ulink url="http://en.wikipedia.org/wiki/Trygve_Reenskaug">Trygve
    Reenskaug</ulink> while working on Smalltalk-80 (1979), where it was
    initially called Model-View-Controller-Editor. MVC was described in
    depth in
    <ulink url="http://www.amazon.co.uk/Design-patterns-elements-reusable-object-oriented/dp/0201633612"><quote>Design
    Patterns: Elements of Reusable Object-Oriented
    Software</quote></ulink> (The <quote>GoF</quote> or <quote>Gang of
    Four</quote> book) in 1994, which played a role in popularizing its
    use.
  </para>
  <sect2 id="smalltalk-80-mvc">
    <title>Smalltalk-80 MVC</title>
    <para>
      It’s important to understand what the original MVC pattern was
      aiming to solve as it has changed quite heavily since the days of
      its origin. Back in the 70’s, graphical user-interfaces were far
      and few between. An approach known as
      <ulink url="http://martinfowler.com/eaaDev/uiArchs.html">Separated
      Presentation</ulink> began to be used as a means to make a clear
      division between domain objects which modeled concepts in the real
      world (e.g a photo, a person) and the presentation objects which
      were rendered to the user’s screen.
    </para>
    <para>
      The Smalltalk-80 implementation of MVC took this concept further
      and had an objective of separating out the application logic from
      the user interface. The idea was that decoupling these parts of
      the application would also allow the reuse of models for other
      interfaces in the application. There are some interesting points
      worth noting about Smalltalk-80’s MVC architecture:
    </para>
    <itemizedlist>
      <listitem>
        <para>
          A Domain element was known as a Model and were ignorant of the
          user-interface (Views and Controllers)
        </para>
      </listitem>
      <listitem>
        <para>
          Presentation was taken care of by the View and the Controller,
          but there wasn’t just a single view and controller. A
          View-Controller pair was required for each element being
          displayed on the screen and so there was no true separation
          between them
        </para>
      </listitem>
      <listitem>
        <para>
          The Controller’s role in this pair was handling user input
          (such as key-presses and click events), doing something
          sensible with them.
        </para>
      </listitem>
      <listitem>
        <para>
          The Observer pattern was relied upon for updating the View
          whenever the Model changed
        </para>
      </listitem>
    </itemizedlist>
    <para>
      Developers are sometimes surprised when they learn that the
      Observer pattern (nowadays commonly implemented as a
      Publish/Subscribe system) was included as a part of MVC’s
      architecture decades ago. In Smalltalk-80’s MVC, the View and
      Controller both observe the Model: anytime the Model changes, the
      Views react. A simple example of this is an application backed by
      stock market data - for the application to show real-time
      information, any change to the data in its Models should result in
      the View being refreshed instantly.
    </para>
    <para>
      Martin Fowler has done an excellent job of writing about the
      <ulink url="http://martinfowler.com/eaaDev/uiArchs.html">origins</ulink>
      of MVC over the years and if you are interested in further
      historical information about Smalltalk-80’s MVC, I recommend
      reading his work.
    </para>
  </sect2>
</sect1>
<sect1 id="mvc-as-we-know-it">
  <title>MVC As We Know It</title>
  <para>
    We’ve reviewed the 70’s, but let us now return to the here and now.
    The MVC pattern has been applied to a diverse range of programming
    languages. For example, the popular Ruby on Rails is an
    implementation of a web application framework based on MVC for the
    Ruby language. JavaScript now has a number of MVC frameworks,
    including Ember.js, JavaScriptMVC, and of course Backbone.js. Given
    the importance of avoiding <quote>spaghetti</quote> code, a term
    which describes code that is very difficult to read or maintain due
    to its lack of structure, let’s look at what the MVC pattern enables
    the Javascript developer to do.
  </para>
  <para>
    MVC is composed of three core components:
  </para>
  <sect2 id="models">
    <title>Models</title>
    <para>
      Models manage the data for an application. They are concerned with
      neither the user-interface nor presentation layers, but instead
      represent structured data that an application may require. When a
      model changes (e.g when it is updated), it will typically notify
      its observers (e.g views, a concept we will cover shortly) that a
      change has occurred so that they may react accordingly.
    </para>
    <para>
      To understand models better, let us imagine we have a JavaScript
      photo gallery application. In a photo gallery, a photo would merit
      its own model, as it represents a unique kind of domain-specific
      data. The Photo model may represent attributes such as a caption,
      image source and additional meta-data. A specific photo would be
      stored in an instance of a model. Here’s an example of a simple
      Photo model implemented with Backbone.js:
    </para>
    <programlisting language="javascript">
var Photo = Backbone.Model.extend({

    // Default attributes for the photo
    defaults: {
      // Ensure that each photo created has an `src`.
      src: &quot;placeholder.jpg&quot;,
      caption: &quot;A default image&quot;,
      viewed: false
    },

    initialize: function() {
    }

});
</programlisting>
    <para>
      The built-in capabilities of models vary across frameworks,
      however it’s common for them to support validation of attributes,
      where attributes represent the properties of the model, such as a
      model identifier. When using models in real-world applications we
      generally also need a way of persisting models. Persistence allows
      us to edit and update models with the knowledge that their most
      recent states will be saved somewhere, for example in a web
      browser’s localStorage data-store or synchronized with a database.
    </para>
    <para>
      A model may also have multiple views observing it. Imagine our
      Photo model contained meta-data such as the longitude and latitude
      where the photo was taken, a list of people present in the photo,
      and a list of tags. A developer could create a single view that
      displayed all these attributes, or might create three separate
      views to display each attribute. The important detail is that the
      Photo model doesn’t care how these views are organized, it simply
      announces updates to its data as necessary. We’ll come back to
      Views in more detail later.
    </para>
    <para>
      It is not uncommon for modern MVC/MV* frameworks to provide a
      means to group models together. In Backbone, these groups are
      called <quote>Collections</quote>. Managing models in groups
      allows us to write application logic based on notifications from
      the group, should any model it contains change. This avoids the
      need to manually observe individual model instances.
    </para>
    <para>
      Here’s how we might group Photo models into a simplified Backbone
      Collection:
    </para>
    <programlisting language="javascript">
var PhotoGallery = Backbone.Collection.extend({

    // Reference to this collection's model.
    model: Photo,

    // Filter down the list of all photos that have been viewed
    viewed: function() {
      return this.filter(function(photo){ return photo.get('viewed'); });
    },

    // Filter down the list to only photos that have not yet been viewed
    unviewed: function() {
      return this.without.apply(this, this.viewed());
    }

});
</programlisting>
    <para>
      If you read older texts on MVC, you may come across a description
      of models as also managing application <quote>state</quote>. In
      JavaScript applications <quote>state</quote> has a specific
      meaning, typically referring to the current <quote>state</quote>
      of a view or sub-view on a user’s screen at a fixed time. State is
      a topic which is regularly discussed when looking at Single-page
      applications, where the concept of state needs to be simulated.
    </para>
  </sect2>
  <sect2 id="views">
    <title>Views</title>
    <para>
      Views are a visual representation of models that present a
      filtered view of their current state. A view typically observes a
      model and is notified when the model changes, allowing the view to
      update itself accordingly. Design pattern literature commonly
      refers to views as <quote>dumb</quote>, given that their knowledge
      of models and controllers in an application is limited.
    </para>
    <para>
      Users interact with views, which usually means reading and editing
      model data. For example, in our photo gallery application example,
      model viewing might happen in a user interface with a big image, a
      caption, and a list of tags. Model editing could be done through
      an <quote>edit</quote> view where a user who has selected a
      specific photo could edit its caption, tags, or other metadata in
      a form.
    </para>
    <para>
      In MVC, the actual task of updating the Model falls to
      Controllers, which we’ll be covering shortly.
    </para>
    <para>
      Let’s explore Views a little further using a simple JavaScript
      example. Below we can see a function that creates a single Photo
      view, consuming both a model instance and a controller instance.
    </para>
    <para>
      We define a <literal>render()</literal> utility within our view
      which is responsible for rendering the contents of the
      <literal>photoModel</literal> using a JavaScript templating engine
      (Underscore templating) and updating the contents of our view,
      referenced by <literal>photoEl</literal>.
    </para>
    <para>
      The <literal>photoModel</literal> then adds our
      <literal>render()</literal> callback as one of its subscribers, so
      that through the Observer pattern it can trigger the view to
      update when the model changes.
    </para>
    <para>
      You may wonder where user interaction comes into play here. When
      users click on any elements within the view, it’s not the view’s
      responsibility to know what to do next. A Controller makes this
      decision. In our sample implementation, this is achieved by adding
      an event listener to <literal>photoEl</literal> which will
      delegate handling the click behavior back to the controller,
      passing the model information along with it in case it’s needed.
    </para>
    <para>
      The benefit of this architecture is that each component plays its
      own separate role in making the application function as needed.
    </para>
    <programlisting language="javascript">
var buildPhotoView = function( photoModel, photoController ){

    var base = document.createElement('div'),
        photoEl = document.createElement('div');

     base.appendChild(photoEl);

     var render= function(){
        // We use a templating library such as Underscore
        // templating which generates the HTML for our
        // photo entry
        photoEl.innerHTML = _.template('photoTemplate', {src: photoModel.getSrc()});
     }

     photoModel.addSubscriber( render );

     photoEl.addEventListener('click', function(){
        photoController.handleEvent('click', photoModel );
     });

     var show = function(){
        photoEl.style.display = '';
     }

     var hide = function(){
        photoEl.style.display = 'none';
     }


     return{
        showView: show,
        hideView: hide
     }

}
</programlisting>
    <para>
      <emphasis role="strong">Templating</emphasis>
    </para>
    <para>
      In the context of JavaScript frameworks that support MVC/MV*, it
      is worth looking more closely at JavaScript templating and its
      relationship to Views.
    </para>
    <para>
      It has long been considered bad practice (and computationally
      expensive) to manually create large blocks of HTML markup
      in-memory through string concatenation. Developers using this
      technique often find themselves iterating through their data,
      wrapping it in nested divs and using outdated techniques such as
      <literal>document.write</literal> to inject the
      <quote>template</quote> into the DOM. This approach often means
      keeping scripted markup inline with standard markup, which can
      quickly become difficult to read and maintain, especially when
      building large applications.
    </para>
    <para>
      JavaScript templating libraries (such as Handlebars.js or
      Mustache) are often used to define templates for views as HTML
      markup containing template variables. These template blocks can be
      either stored externally or within script tags with a custom type
      (e.g <quote>text/template</quote>). Variables are deliminated
      using a variable syntax (e.g {{name}}). Javascript template
      libraries typically accept data in JSON, and the grunt work of
      populating templates with data is taken care of by the framework
      itself. This has a several benefits, particularly when opting to
      store templates externally as this can let applications load
      templates dynamically on an as-needed basis.
    </para>
    <para>
      Let’s compare two examples of HTML templates. One is implemented
      using the popular Handlebars.js library, and the other uses
      Underscore’s <quote>microtemplates</quote>.
    </para>
    <para>
      <emphasis role="strong">Handlebars.js:</emphasis>
    </para>
    <programlisting language="html">
&lt;li class=&quot;photo&quot;&gt;
  &lt;h2&gt;{{caption}}&lt;/h2&gt;
  &lt;img class=&quot;source&quot; src=&quot;{{src}}&quot;/&gt;
  &lt;div class=&quot;meta-data&quot;&gt;
    {{metadata}}
  &lt;/div&gt;
&lt;/li&gt;
</programlisting>
    <para>
      <emphasis role="strong">Underscore.js Microtemplates:</emphasis>
    </para>
    <programlisting language="html">
&lt;li class=&quot;photo&quot;&gt;
  &lt;h2&gt;&lt;%= caption %&gt;&lt;/h2&gt;
  &lt;img class=&quot;source&quot; src=&quot;&lt;%= src %&gt;&quot;/&gt;
  &lt;div class=&quot;meta-data&quot;&gt;
    &lt;%= metadata %&gt;
  &lt;/div&gt;
&lt;/li&gt;
</programlisting>
    <para>
      You may also use double curly brackets (i.e
      <literal>{{}}</literal>) (or any other tag you feel comfortable
      with) in Microtemplates. In the case of curly brackets, this can
      be done by setting the Underscore
      <literal>templateSettings</literal> attribute as follows:
    </para>
    <programlisting language="javascript">
_.templateSettings = { interpolate : /\{\{(.+?)\}\}/g };
</programlisting>
    <para>
      <emphasis role="strong">A note on navigation and state</emphasis>
    </para>
    <para>
      It is also worth noting that in classical web development,
      navigating between independent views required the use of a page
      refresh. In single-page JavaScript applications, however, once
      data is fetched from a server via Ajax, it can be dynamically
      rendered in a new view within the same page. Since this doesn’t
      automatically update the URL, the role of navigation thus falls to
      a <quote>router</quote>, which assists in managing application
      state (e.g allowing users to bookmark a particular view they have
      navigated to). As routers are however neither a part of MVC nor
      present in every MVC-like framework, I will not be going into them
      in greater detail in this section.
    </para>
  </sect2>
  <sect2 id="controllers">
    <title>Controllers</title>
    <para>
      Controllers are an intermediary between models and views which are
      classically responsible for two tasks: they both update the view
      when the model changes and update the model when the user
      manipulates the view.
    </para>
    <para>
      In our photo gallery application, a controller would be
      responsible for handling changes the user made to the edit view
      for a particular photo, updating a specific photo model when a
      user has finished editing.
    </para>
    <para>
      It’s with controllers that most JavaScript MVC frameworks depart
      from this interpretation of the MVC pattern. The reasons for this
      vary, but in my opinion, Javascript framework authors likely
      initially looked at server-side interpretations of MVC (such as
      Ruby on Rails), realized that that approach didn’t translate 1:1
      on the client-side, and so re-interpreted the C in MVC to solve
      their state management problem. This was a clever approach, but it
      can make it hard for developers coming to MVC for the first time
      to understand both the classical MVC pattern and the
      <quote>proper</quote> role of controllers in other non-Javascript
      frameworks.
    </para>
    <para>
      So does Backbone.js have Controllers? Not really. Backbone’s Views
      typically contain <quote>controller</quote> logic, and Routers
      (discussed below) are used to help manage application state, but
      neither are true Controllers according to classical MVC.
    </para>
    <para>
      In this respect, contrary to what might be mentioned in the
      official documentation or in blog posts, Backbone is neither a
      truly MVC/MVP nor MVVM framework. It’s in fact better to see it a
      member of the MV* family which approaches architecture in its own
      way. There is of course nothing wrong with this, but it is
      important to distinguish between classical MVC and MV* should you
      be relying on discussions of MVC to help with your Backbone
      projects.
    </para>
  </sect2>
  <sect2 id="controllers-in-spine.js-vs-backbone.js">
    <title>Controllers in Spine.js vs Backbone.js</title>
    <para>
      <emphasis role="strong">Spine.js</emphasis>
    </para>
    <para>
      We now know that controllers are traditionally responsible for
      updating the view when the model changes (and similarly the model
      when the user updates the view). Since Backbone doesn’t have its
      <emphasis role="strong">own</emphasis> explicit controllers, it’s
      useful to review the controller from another MVC framework to
      appreciate the difference in implementations. Let’s take a look at
      <ulink url="http://spinejs.com/">Spine.js</ulink>:
    </para>
    <para>
      In this example, we’re going to have a controller called
      <literal>PhotosController</literal> which will be in charge of
      individual photos in the application. It will ensure that when the
      view updates (e.g a user edited the photo meta-data) the
      corresponding model does too.
    </para>
    <para>
      (Note: We won’t be delving heavily into Spine.js beyond this
      example, but it’s worth looking at it to learn more about
      Javascript frameworks in general.)
    </para>
    <programlisting language="javascript">
// Controllers in Spine are created by inheriting from Spine.Controller

var PhotosController = Spine.Controller.sub({
  init: function(){
    this.item.bind(&quot;update&quot;, this.proxy(this.render));
    this.item.bind(&quot;destroy&quot;, this.proxy(this.remove));
  },

  render: function(){
    // Handle templating
    this.replace($(&quot;#photoTemplate&quot;).tmpl(this.item));
    return this;
  },

  remove: function(){
    this.el.remove();
    this.release();
  }
});
</programlisting>
    <para>
      In Spine, controllers are considered the glue for an application,
      adding and responding to DOM events, rendering templates and
      ensuring that views and models are kept in sync (which makes sense
      in the context of what we know to be a controller).
    </para>
    <para>
      What we’re doing in the above example is setting up listeners in
      the <literal>update</literal> and <literal>destroy</literal>
      events using <literal>render()</literal> and
      <literal>remove()</literal>. When a photo entry gets updated, we
      re-render the view to reflect the changes to the meta-data.
      Similarly, if the photo gets deleted from the gallery, we remove
      it from the view. In case you were wondering about the
      <literal>tmpl()</literal> function in the code snippet: in the
      <literal>render()</literal> function, we’re using this to render a
      JavaScript template called #photoTemplate which simply returns a
      HTML string used to replace the controller’s current element.
    </para>
    <para>
      What this provides us with is a very lightweight, simple way to
      manage changes between the model and the view.
    </para>
    <para>
      <emphasis role="strong">Backbone.js</emphasis>
    </para>
    <para>
      Later on in this section we’re going to revisit the differences
      between Backbone and traditional MVC, but for now let’s focus on
      controllers.
    </para>
    <para>
      In Backbone, controller logic is shared between Backbone.View and
      Backbone.Router. Earlier releases of Backbone contained something
      called Backbone.Controller, but it was renamed to Router to
      clarify its role.
    </para>
    <para>
      A Router’s main purpose is to translate URL requests into
      application states. When a user browses to the URL
      www.example.com/photos/42, a Router could be used to show the
      photo with that ID, and to define what application behavior should
      be run in response to that request. Routers
      <emphasis>can</emphasis> contain traditional controller
      responsibilities, such as binding the events between models and
      views, or rendering parts of the page. However, Backbone
      contributor Tim Branyen has pointed out that it’s possible to get
      away without needing Backbone.Router at all for this, so a way to
      think about it using the Router paradigm is probably:
    </para>
    <programlisting language="javascript">
var PhotoRouter = Backbone.Router.extend({
  routes: { &quot;photos/:id&quot;: &quot;route&quot; },

  route: function(id) {
    var item = photoCollection.get(id);
    var view = new PhotoView({ model: item });

    something.html( view.render().el );
  }
}):
</programlisting>
  </sect2>
</sect1>
<sect1 id="what-does-mvc-give-us">
  <title>What does MVC give us?</title>
  <para>
    To summarize, the separation of concerns in MVC facilitates
    modularization of an application’s functionality and enables:
  </para>
  <itemizedlist>
    <listitem>
      <para>
        Easier overall maintenance. When updates need to be made to the
        application it is clear whether the changes are data-centric,
        meaning changes to models and possibly controllers, or merely
        visual, meaning changes to views.<literallayout></literallayout>
      </para>
    </listitem>
    <listitem>
      <para>
        Decoupling models and views means that it’s straight-forward to
        write unit tests for business
        logic<literallayout></literallayout>
      </para>
    </listitem>
    <listitem>
      <para>
        Duplication of low-level model and controller code is eliminated
        across the application
      </para>
    </listitem>
    <listitem>
      <para>
        Depending on the size of the application and separation of
        roles, this modularity allows developers responsible for core
        logic and developers working on the user-interfaces to work
        simultaneously
      </para>
    </listitem>
  </itemizedlist>
  <sect2 id="delving-deeper">
    <title>Delving deeper</title>
    <para>
      Right now, you likely have a basic understanding of what the MVC
      pattern provides, but for the curious, we’ll explore it a little
      further.
    </para>
    <para>
      The GoF (Gang of Four) do not refer to MVC as a design pattern,
      but rather consider it a <quote>set of classes to build a user
      interface</quote>. In their view, it’s actually a variation of
      three other classical design patterns: the Observer (Pub/Sub),
      Strategy and Composite patterns. Depending on how MVC has been
      implemented in a framework, it may also use the Factory and
      Decorator patterns. I’ve covered some of these patterns in my
      other free book, JavaScript Design Patterns For Beginners if you
      would like to read into them further.
    </para>
    <para>
      As we’ve discussed, models represent application data, while views
      handle what the user is presented on screen. As such, MVC relies
      on Pub/Sub for some of its core communication (something that
      surprisingly isn’t covered in many articles about the MVC
      pattern). When a model is changed it <quote>publishes</quote> to
      the rest of the application that it has been updated. The
      <quote>subscriber</quote>–generally a Controller–then updates the
      view accordingly. The observer-viewer nature of this relationship
      is what facilitates multiple views being attached to the same
      model.
    </para>
    <para>
      For developers interested in knowing more about the decoupled
      nature of MVC (once again, depending on the implementation), one
      of the goals of the pattern is to help define one-to-many
      relationships between a topic and its observers. When a topic
      changes, its observers are updated. Views and controllers have a
      slightly different relationship. Controllers facilitate views to
      respond to different user input and are an example of the Strategy
      pattern.
    </para>
  </sect2>
  <sect2 id="summary">
    <title>Summary</title>
    <para>
      Having reviewed the classical MVC pattern, your should now
      understand how it allows developers to cleanly separate concerns
      in an application. You should also now appreciate how JavaScript
      MVC frameworks may differ in their interpretation of MVC, and how
      they share some of the fundamental concepts of the original
      pattern.
    </para>
    <para>
      When reviewing a new JavaScript MVC/MV* framework, remember - it
      can be useful to step back and consider how it’s opted to approach
      Models, Views, Controllers or other alternatives, as this can
      better help you grok how the framework expects to be used.
    </para>
  </sect2>
</sect1>
<sect1 id="mvp">
  <title>MVP</title>
  <para>
    Model-view-presenter (MVP) is a derivative of the MVC design pattern
    which focuses on improving presentation logic. It originated at a
    company named
    <ulink url="http://en.wikipedia.org/wiki/Taligent">Taligent</ulink>
    in the early 1990s while they were working on a model for a C++
    CommonPoint environment. Whilst both MVC and MVP target the
    separation of concerns across multiple components, there are some
    fundamental differences between them.
  </para>
  <para>
    For the purposes of this summary we will focus on the version of MVP
    most suitable for web-based architectures.
  </para>
  <sect2 id="models-views-presenters">
    <title>Models, Views &amp; Presenters</title>
    <para>
      The P in MVP stands for presenter. It’s a component which contains
      the user-interface business logic for the view. Unlike MVC,
      invocations from the view are delegated to the presenter, which
      are decoupled from the view and instead talk to it through an
      interface. This allows for all kinds of useful things such as
      being able to mock views in unit tests.
    </para>
    <para>
      The most common implementation of MVP is one which uses a Passive
      View (a view which is for all intents and purposes
      <quote>dumb</quote>), containing little to no logic. MVP models
      are almost identical to MVC models and handle application data.
      The presenter acts as a mediator which talks to both the view and
      model, however both of these are isolated from each other. They
      effectively bind models to views, a responsibility held by
      Controllers in MVC. Presenters are at the heart of the MVP pattern
      and as you can guess, incorporate the presentation logic behind
      views.
    </para>
    <para>
      Solicited by a view, presenters perform any work to do with user
      requests and pass data back to them. In this respect, they
      retrieve data, manipulate it and determine how the data should be
      displayed in the view. In some implementations, the presenter also
      interacts with a service layer to persist data (models). Models
      may trigger events but it’s the presenter’s role to subscribe to
      them so that it can update the view. In this passive architecture,
      we have no concept of direct data binding. Views expose setters
      which presenters can use to set data.
    </para>
    <para>
      The benefit of this change from MVC is that it increases the
      testability of your application and provides a more clean
      separation between the view and the model. This isn’t however
      without its costs as the lack of data binding support in the
      pattern can often mean having to take care of this task
      separately.
    </para>
    <para>
      Although a common implementation of a
      <ulink url="http://martinfowler.com/eaaDev/PassiveScreen.html">Passive
      View</ulink> is for the view to implement an interface, there are
      variations on it, including the use of events which can decouple
      the View from the Presenter a little more. As we don’t have the
      interface construct in JavaScript, we’re using it more as more a
      protocol than an explicit interface here. It’s technically still
      an API and it’s probably fair for us to refer to it as an
      interface from that perspective.
    </para>
    <para>
      There is also a
      <ulink url="http://martinfowler.com/eaaDev/SupervisingPresenter.html">Supervising
      Controller</ulink> variation of MVP, which is closer to the MVC
      and
      <ulink url="http://en.wikipedia.org/wiki/Model_View_ViewModel">MVVM</ulink>
      patterns as it provides data-binding from the Model directly from
      the View. Key-value observing (KVO) plugins (such as Derick
      Bailey’s Backbone.ModelBinding plugin) introduce this idea of a
      Supervising Controller to Backbone.
    </para>
  </sect2>
</sect1>
<sect1 id="mvp-or-mvc">
  <title>MVP or MVC?</title>
  <para>
    MVP is generally used most often in enterprise-level applications
    where it’s necessary to reuse as much presentation logic as
    possible. Applications with very complex views and a great deal of
    user interaction may find that MVC doesn’t quite fit the bill here
    as solving this problem may mean heavily relying on multiple
    controllers. In MVP, all of this complex logic can be encapsulated
    in a presenter, which can simplify maintenance greatly.
  </para>
  <para>
    As MVP views are defined through an interface and the interface is
    technically the only point of contact between the system and the
    view (other than a presenter), this pattern also allows developers
    to write presentation logic without needing to wait for designers to
    produce layouts and graphics for the application.
  </para>
  <para>
    Depending on the implementation, MVP may be more easy to
    automatically unit test than MVC. The reason often cited for this is
    that the presenter can be used as a complete mock of the
    user-interface and so it can be unit tested independent of other
    components. In my experience this really depends on the languages
    you are implementing MVP in (there’s quite a difference between
    opting for MVP for a JavaScript project over one for say, ASP.net).
  </para>
  <para>
    At the end of the day, the underlying concerns you may have with MVC
    will likely hold true for MVP given that the differences between
    them are mainly semantic. As long as you are cleanly separating
    concerns into models, views and controllers (or presenters) you
    should be achieving most of the same benefits regardless of the
    pattern you opt for.
  </para>
</sect1>
<sect1 id="mvc-mvp-and-backbone.js">
  <title>MVC, MVP and Backbone.js</title>
  <para>
    There are very few, if any architectural JavaScript frameworks that
    claim to implement the MVC or MVP patterns in their classical form
    as many JavaScript developers don’t view MVC and MVP as being
    mutually exclusive (we are actually more likely to see MVP strictly
    implemented when looking at web frameworks such as ASP.net or GWT).
    This is because it’s possible to have additional presenter/view
    logic in your application and yet still consider it a flavor of MVC.
  </para>
  <para>
    Backbone contributor <ulink url="http://ireneros.com/">Irene
    Ros</ulink> subscribes to this way of thinking as when she separates
    Backbone views out into their own distinct components, she needs
    something to actually assemble them for her. This could either be a
    controller route (such as a <literal>Backbone.Router</literal>,
    covered later in the book) or a callback in response to data being
    fetched.
  </para>
  <para>
    That said, some developers do however feel that Backbone.js better
    fits the description of MVP than it does MVC . Their view is that:
  </para>
  <itemizedlist>
    <listitem>
      <para>
        The presenter in MVP better describes the
        <literal>Backbone.View</literal> (the layer between View
        templates and the data bound to it) than a controller does
      </para>
    </listitem>
    <listitem>
      <para>
        The model fits <literal>Backbone.Model</literal> (it isn’t that
        different from the classical MVC
        <quote>Model</quote>)<literallayout></literallayout>
      </para>
    </listitem>
    <listitem>
      <para>
        The views best represent templates (e.g Handlebars/Mustache
        markup templates)
      </para>
    </listitem>
  </itemizedlist>
  <para>
    A response to this could be that the view can also just be a View
    (as per MVC) because Backbone is flexible enough to let it be used
    for multiple purposes. The V in MVC and the P in MVP can both be
    accomplished by <literal>Backbone.View</literal> because they’re
    able to achieve two purposes: both rendering atomic components and
    assembling those components rendered by other views.
  </para>
  <para>
    We’ve also seen that in Backbone the responsibility of a controller
    is shared with both the Backbone.View and Backbone.Router and in the
    following example we can actually see that aspects of that are
    certainly true.
  </para>
  <para>
    Here, our Backbone <literal>PhotoView</literal> uses the Observer
    pattern to <quote>subscribe</quote> to changes to a View’s model in
    the line <literal>this.model.bind('change',...)</literal>. It also
    handles templating in the <literal>render()</literal> method, but
    unlike some other implementations, user interaction is also handled
    in the View (see <literal>events</literal>).
  </para>
  <programlisting language="javascript">
var PhotoView = Backbone.View.extend({

    //... is a list tag.
    tagName: &quot;li&quot;,

    // Pass the contents of the photo template through a templating
    // function, cache it for a single photo
    template: _.template($('#photo-template').html()),

    // The DOM events specific to an item.
    events: {
      &quot;click img&quot; : &quot;toggleViewed&quot;
    },

    // The PhotoView listens for changes to its model, re-rendering. Since there's
    // a one-to-one correspondence between a **Photo** and a **PhotoView** in this
    // app, we set a direct reference on the model for convenience.

    initialize: function() {
      _.bindAll(this, 'render');
      this.model.bind('change', this.render);
      this.model.bind('destroy', this.remove);
    },

    // Re-render the photo entry
    render: function() {
      $(this.el).html(this.template(this.model.toJSON()));
      return this;
    },

    // Toggle the `&quot;viewed&quot;` state of the model.
    toggleViewed: function() {
      this.model.viewed();
    }

});
</programlisting>
  <para>
    Another (quite different) opinion is that Backbone more closely
    resembles
    <ulink url="http://martinfowler.com/eaaDev/uiArchs.html#ModelViewController">Smalltalk-80
    MVC</ulink>, which we went through earlier.
  </para>
  <para>
    As regular Backbone user Derick Bailey has
    <ulink url="http://lostechies.com/derickbailey/2011/12/23/backbone-js-is-not-an-mvc-framework/">written</ulink>,
    it’s ultimately best not to force Backbone to fit any specific
    design patterns. Design patterns should be considered flexible
    guides to how applications may be structured and in this respect,
    Backbone doesn’t fit either MVC nor MVP perfectly. Instead, it
    borrows some of the best concepts from multiple architectural
    patterns and creates a flexible framework that just works well. Call
    it <emphasis role="strong">the Backbone way</emphasis>, MV* or
    whatever helps reference its flavor of application architecture.
  </para>
  <para>
    It <emphasis>is</emphasis> however worth understanding where and why
    these concepts originated, so I hope that my explanations of MVC and
    MVP have been of help. Most structural JavaScript frameworks will
    adopt their own take on classical patterns, either intentionally or
    by accident, but the important thing is that they help us develop
    applications which are organized, clean and can be easily
    maintained.
  </para>
</sect1>
<sect1 id="fast-facts">
  <title>Fast facts</title>
  <sect2 id="backbone.js">
    <title>Backbone.js</title>
    <itemizedlist>
      <listitem>
        <para>
          Core components: Model, View, Collection, Router. Enforces its
          own flavor of MV*
        </para>
      </listitem>
      <listitem>
        <para>
          Good documentation, with more improvements on the way
        </para>
      </listitem>
      <listitem>
        <para>
          Used by large companies such as SoundCloud and Foursquare to
          build non-trivial applications
        </para>
      </listitem>
      <listitem>
        <para>
          Event-driven communication between views and models. As we’ll
          see, it’s relatively straight-forward to add event listeners
          to any attribute in a model, giving developers fine-grained
          control over what changes in the view
        </para>
      </listitem>
      <listitem>
        <para>
          Supports data bindings through manual events or a separate
          Key-value observing (KVO) library
        </para>
      </listitem>
      <listitem>
        <para>
          Great support for RESTful interfaces out of the box, so models
          can be easily tied to a backend
        </para>
      </listitem>
      <listitem>
        <para>
          Extensive eventing system. It’s
          <ulink url="http://lostechies.com/derickbailey/2011/07/19/references-routing-and-the-event-aggregator-coordinating-views-in-backbone-js/">trivial</ulink>
          to add support for pub/sub in Backbone
        </para>
      </listitem>
      <listitem>
        <para>
          Prototypes are instantiated with the <literal>new</literal>
          keyword, which some developers prefer
        </para>
      </listitem>
      <listitem>
        <para>
          Agnostic about templating frameworks, however Underscore’s
          micro-templating is available by default. Backbone works well
          with libraries like Handlebars
        </para>
      </listitem>
      <listitem>
        <para>
          Doesn’t support deeply nested models, though there are
          Backbone plugins such as
          <ulink url="https://github.com/PaulUithol/Backbone-relational">this</ulink>
          which can help<literallayout></literallayout>
        </para>
      </listitem>
      <listitem>
        <para>
          Clear and flexible conventions for structuring applications.
          Backbone doesn’t force usage of all of its components and can
          work with only those needed.
        </para>
      </listitem>
    </itemizedlist>
  </sect2>
</sect1>
<sect1 id="the-basics">
  <title>## <a name="thebasics">The Basics</a></title>
  <sect2 id="what-is-backbone">
    <title>What is Backbone?</title>
    <para>
      Backbone.js is one of a number of JavaScript frameworks for
      creating MVC-like web applications. On the front-end, it’s my
      architectural framework of choice as it’s both mature, relatively
      lightweight and can be easily tested using third-party toolkits
      such as Jasmine or QUnit. Other MVC frameworks you may be familiar
      with include Ember.js (SproutCore 2.0), Spine, YUILibrary and
      JavaScriptMVC.
    </para>
    <para>
      Backbone is maintained by a number of contributors, most notably:
      Jeremy Ashkenas, creator of CoffeeScript, Docco and Underscore.js.
      As Jeremy is a believer in detailed documentation, there’s a level
      of comfort in knowing you’re unlikely to run into issues which are
      either not explained in the official docs or which can’t be nailed
      down with some assistance from the #documentcloud IRC channel. I
      strongly recommend using the latter if you find yourself getting
      stuck.
    </para>
  </sect2>
  <sect2 id="why-should-you-consider-using-it">
    <title>Why should you consider using it?</title>
    <para>
      Backbone’s main benefits, regardless of your target platform or
      device, include helping:
    </para>
    <itemizedlist>
      <listitem>
        <para>
          Organize the structure to your application
        </para>
      </listitem>
      <listitem>
        <para>
          Simplify server-side persistence
        </para>
      </listitem>
      <listitem>
        <para>
          Decouple the DOM from your page’s data
        </para>
      </listitem>
      <listitem>
        <para>
          Model data, views and routers in a succinct manner
        </para>
      </listitem>
      <listitem>
        <para>
          Provide DOM, model and collection synchronization
        </para>
      </listitem>
    </itemizedlist>
  </sect2>
</sect1>
<sect1 id="the-basics-1">
  <title>The Basics</title>
  <para>
    In this section, you’ll learn the essentials of Backbone’s models,
    views, collections and routers, as well as about using namespacing
    to organize your code. This isn’t meant as a replacement for the
    official documentation, but it will help you understand many of the
    core concepts behind Backbone before you start building applications
    with it.
  </para>
  <itemizedlist>
    <listitem>
      <para>
        Models
      </para>
    </listitem>
    <listitem>
      <para>
        Collections
      </para>
    </listitem>
    <listitem>
      <para>
        Routers
      </para>
    </listitem>
    <listitem>
      <para>
        Views
      </para>
    </listitem>
    <listitem>
      <para>
        Namespacing
      </para>
    </listitem>
  </itemizedlist>
  <sect2 id="models-1">
    <title><a name="models">Models</a></title>
    <para>
      Backbone models contain interactive data for an application as
      well as the logic around this data. For example, we can use a
      model to represent the concept of a photo object including its
      attributes like tags, titles and a location.
    </para>
    <para>
      Models can be created by extending
      <literal>Backbone.Model</literal> as follows:
    </para>
    <programlisting language="javascript">
var Photo = Backbone.Model.extend({
    defaults: {
        src: 'placeholder.jpg',
        title: 'an image placeholder',
        coordinates: [0,0]
    },
    initialize: function(){
        this.bind(&quot;change:src&quot;, function(){
            var src = this.get(&quot;src&quot;);
            console.log('Image source updated to ' + src);
        });
    },
    changeSrc: function( source ){
        this.set({ src: source });
    }
});

var somePhoto = new Photo({ src: &quot;test.jpg&quot;, title:&quot;testing&quot;});
somePhoto.changeSrc(&quot;magic.jpg&quot;); // which triggers &quot;change:src&quot; and logs an update message to the console.
</programlisting>
    <sect3 id="initialization">
      <title>Initialization</title>
      <para>
        The <literal>initialize()</literal> method is called when a new
        instance of a model is created. Its use is optional, however
        you’ll see why it’s good practice to use it below.
      </para>
      <programlisting language="javascript">
var Photo = Backbone.Model.extend({
    initialize: function(){
        console.log('this model has been initialized');
    }
});

// We can then create our own instance of a photo as follows:
var myPhoto = new Photo();
</programlisting>
    </sect3>
    <sect3 id="getters-setters">
      <title>Getters &amp; Setters</title>
      <para>
        <emphasis role="strong">Model.get()</emphasis>
      </para>
      <para>
        <literal>Model.get()</literal> provides easy access to a model’s
        attributes. Attributes which are passed through to the model on
        instantiation are instantly available for retrieval.
      </para>
      <programlisting language="javascript">
var myPhoto = new Photo({ title: &quot;My awesome photo&quot;,
                          src:&quot;boston.jpg&quot;,
                          location: &quot;Boston&quot;,
                          tags:['the big game', 'vacation']}),

    title = myPhoto.get(&quot;title&quot;), //My awesome photo
    location = myPhoto.get(&quot;location&quot;), //Boston
    tags = myPhoto.get(&quot;tags&quot;), // ['the big game','vacation']
    photoSrc = myPhoto.get(&quot;src&quot;); //boston.jpg
</programlisting>
      <para>
        Alternatively, if you wish to directly access all of the
        attributes in a model’s instance directly, you can achieve this
        as follows:
      </para>
      <programlisting language="javascript">
var myAttributes = myPhoto.attributes;
console.log(myAttributes);
</programlisting>
      <para>
        It is best practice to use <literal>Model.set()</literal> or
        direct instantiation to set the values of a model’s attributes.
      </para>
      <para>
        Accessing <literal>Model.attributes</literal> directly is
        generally discouraged. Instead, should you need to read or clone
        data, <literal>Model.toJSON()</literal> is recommended for this
        purpose. If you would like to access or copy a model’s
        attributes for purposes such as JSON stringification (e.g. for
        serialization prior to being passed to a view), this can be
        achieved using <literal>Model.toJSON()</literal>:
      </para>
      <programlisting language="javascript">
var myAttributes = myPhoto.toJSON();
console.log(myAttributes);
/* this returns { title: &quot;My awesome photo&quot;,
             src:&quot;boston.jpg&quot;,
             location: &quot;Boston&quot;,
             tags:['the big game', 'vacation']}*/
</programlisting>
    </sect3>
    <sect3 id="model.set">
      <title>Model.set()</title>
      <para>
        <literal>Model.set()</literal> allows us to pass attributes into
        an instance of our model. Attributes can either be set during
        initialization or at any time afterwards. It’s important to
        avoid trying to set a Model’s attributes directly (for example
        Model.caption = <quote>A new caption</quote>). Backbone uses
        Model.set() to know when to broadcast that a model’s data has
        changed.
      </para>
      <programlisting language="javascript">
var Photo = Backbone.Model.extend({
    initialize: function(){
        console.log('this model has been initialized');
    }
});

// Setting the value of attributes via instantiation
var myPhoto = new Photo({ title: 'My awesome photo', location: 'Boston' });

var myPhoto2 = new Photo();

// Setting the value of attributes through Model.set()
myPhoto2.set({ title:'Vacation in Florida', location: 'Florida' });
</programlisting>
      <para>
        <emphasis role="strong">Default values</emphasis>
      </para>
      <para>
        There are times when you want your model to have a set of
        default values (e.g. in a scenario where a complete set of data
        isn’t provided by the user). This can be set using a property
        called <literal>defaults</literal> in your model.
      </para>
      <programlisting language="javascript">
var Photo = Backbone.Model.extend({
    defaults:{
        title: 'Another photo!',
        tags: ['untagged'],
        location: 'home',
        src: 'placeholder.jpg'
    },
    initialize: function(){
    }
});

var myPhoto = new Photo({ location: &quot;Boston&quot;,
                          tags:['the big game', 'vacation']}),
    title = myPhoto.get(&quot;title&quot;), //Another photo!
    location = myPhoto.get(&quot;location&quot;), //Boston
    tags = myPhoto.get(&quot;tags&quot;), // ['the big game','vacation']
    photoSrc = myPhoto.get(&quot;src&quot;); //placeholder.jpg
</programlisting>
      <para>
        <emphasis role="strong">Listening for changes to your
        model</emphasis>
      </para>
      <para>
        Any and all of the attributes in a Backbone model can have
        listeners bound to them which detect when their values change.
        Listeners can be added to the <literal>initialize()</literal>
        function:
      </para>
      <programlisting language="javascript">
this.bind('change', function(){
    console.log('values for this model have changed');
});
</programlisting>
      <para>
        In the following example, we log a message whenever a specific
        attribute (the title of our Photo model) is altered.
      </para>
      <programlisting language="javascript">
var Photo = Backbone.Model.extend({
    defaults:{
        title: 'Another photo!',
        tags: ['untagged'],
        location: 'home',
        src: 'placeholder.jpg'
    },
    initialize: function(){
        console.log('this model has been initialized');
        this.bind(&quot;change:title&quot;, function(){
            var title = this.get(&quot;title&quot;);
            console.log(&quot;My title has been changed to.. &quot; + title);
        });
    },

    setTitle: function(newTitle){
        this.set({ title: newTitle });
    }
});

var myPhoto = new Photo({ title:&quot;Fishing at the lake&quot;, src:&quot;fishing.jpg&quot;});
myPhoto.setTitle('Fishing at sea');
//logs 'My title has been changed to.. Fishing at sea'
</programlisting>
      <para>
        <emphasis role="strong">Validation</emphasis>
      </para>
      <para>
        Backbone supports model validation through
        <literal>Model.validate()</literal>, which allows checking the
        attribute values for a model prior to them being set.
      </para>
      <para>
        Validation functions can be as simple or complex as necessary.
        If the attributes provided are valid, nothing should be returned
        from <literal>.validate()</literal>. If they are invalid, a
        custom error can be returned instead.
      </para>
      <para>
        A basic example for validation can be seen below:
      </para>
      <programlisting language="javascript">
var Photo = Backbone.Model.extend({
    validate: function(attribs){
        if(attribs.src === undefined){
            return &quot;Remember to set a source for your image!&quot;;
        }
    },

    initialize: function(){
        console.log('this model has been initialized');
        this.bind(&quot;error&quot;, function(model, error){
            console.log(error);
        });
    }
});

var myPhoto = new Photo();
myPhoto.set({ title: &quot;On the beach&quot; });
//logs Remember to set a source for your image!
</programlisting>
    </sect3>
  </sect2>
  <sect2 id="views-1">
    <title><a name="views">Views</a></title>
    <para>
      Views in Backbone don’t contain the markup for your application,
      but rather they are there to support models by defining the logic
      for how they should be represented to the user. This is usually
      achieved using JavaScript templating (e.g. Mustache, jQuery-tmpl,
      etc.). A view’s <literal>render()</literal> function can be bound
      to a model’s <literal>change()</literal> event, allowing the view
      to always be up to date without requiring a full page refresh.
    </para>
    <sect3 id="creating-new-views">
      <title>Creating new views</title>
      <para>
        Similar to the previous sections, creating a new view is
        relatively straight-forward. To create a new View, simply extend
        <literal>Backbone.View</literal>. I’ll explain this code in
        detail below:
      </para>
      <programlisting language="javascript">
var PhotoSearch = Backbone.View.extend({
    el: $('#results'),
    render: function( event ){
        var compiled_template = _.template( $(&quot;#results-template&quot;).html() );
        this.el.html( compiled_template(this.model.toJSON()) );
        return this; //recommended as this enables calls to be chained.
    },
    events: {
        &quot;submit #searchForm&quot;: &quot;search&quot;,
        &quot;click .reset&quot;: &quot;reset&quot;,
        &quot;click .advanced&quot;: &quot;switchContext&quot;
    },
    search: function( event ){
        //executed when a form '#searchForm' has been submitted
    },
    reset: function( event ){
        //executed when an element with class &quot;reset&quot; has been clicked.
    },
    switchContext: function( event ){
        //executed when an element with class &quot;advanced&quot; has been clicked.
    }
});
</programlisting>
    </sect3>
    <sect3 id="what-is-el">
      <title>What is <literal>el</literal>?</title>
      <para>
        <literal>el</literal> is basically a reference to a DOM element
        and all views must have one. It allows for all of the contents
        of a view to be inserted into the DOM at once, which makes for
        faster rendering as browser performs the minimum required
        reflows and repaints.
      </para>
      <para>
        There are two ways to attach a DOM element to a view: the
        element already exists in the page or a new element is created
        for the view and added manually by the developer. If the element
        already exists in the page, you can set <literal>el</literal> as
        either a CSS selector that matches the element or a simple
        reference to the DOM element.
      </para>
      <programlisting language="javascript">
el: '#footer',
// OR
el: document.getElementById( 'footer' )
</programlisting>
      <para>
        If you want to create a new element for you view, set any
        combination of the following view’s properties:
        <literal>tagName</literal>, <literal>id</literal> and
        <literal>className</literal>. A new element will be created for
        you by the framework and a reference to it will be available at
        the <literal>el</literal> property.
      </para>
      <programlisting>
tagName: 'p', // required, but defaults to 'div' if not set
className: 'container', // optional, you can assign multiple classes to this property like so 'container homepage'
id: 'header', // optional
</programlisting>
      <para>
        The above code creates the <literal>DOMElement</literal> below
        but doesn’t append it to the DOM.
      </para>
      <programlisting>
&lt;p id=&quot;header&quot; class=&quot;container&quot;&gt;&lt;/p&gt;
</programlisting>
      <para>
        <emphasis role="strong">Understanding
        <literal>render()</literal></emphasis>
      </para>
      <para>
        <literal>render()</literal> is an optional function that defines
        the logic for rendering a template. We’ll use Underscore’s
        micro-templating in these examples, but remember you can use
        other templating frameworks if you prefer.
      </para>
      <para>
        The <literal>_.template</literal> method in Underscore compiles
        JavaScript templates into functions which can be evaluated for
        rendering. In the above view, I’m passing the markup from a
        template with id <literal>results-template</literal> to
        <literal>_.template()</literal> to be compiled. Next, I set the
        html of the <literal>el</literal> DOM element to the output of
        processing a JSON version of the model associated with the view
        through the compiled template.
      </para>
      <para>
        Presto! This populates the template, giving you a data-complete
        set of markup in just a few short lines of code.
      </para>
      <para>
        <emphasis role="strong">The <literal>events</literal>
        attribute</emphasis>
      </para>
      <para>
        The Backbone <literal>events</literal> attribute allows us to
        attach event listeners to either custom selectors, or directly
        to <literal>el</literal> if no selector is provided. An event
        takes the form
        <literal>{&quot;eventName selector&quot;: &quot;callbackFunction&quot;}</literal>
        and a number of event-types are supported, including
        <literal>click</literal>, <literal>submit</literal>,
        <literal>mouseover</literal>, <literal>dblclick</literal> and
        more.
      </para>
      <para>
        What isn’t instantly obvious is that under the bonnet, Backbone
        uses jQuery’s <literal>.delegate()</literal> to provide instant
        support for event delegation but goes a little further,
        extending it so that <literal>this</literal> always refers to
        the current view object. The only thing to really keep in mind
        is that any string callback supplied to the events attribute
        must have a corresponding function with the same name within the
        scope of your view.
      </para>
    </sect3>
  </sect2>
  <sect2 id="collections">
    <title><a name="collections">Collections</a></title>
    <para>
      Collections are sets of Models and are created by extending
      <literal>Backbone.Collection</literal>.
    </para>
    <para>
      Normally, when creating a collection you’ll also want to pass
      through a property specifying the model that your collection will
      contain, as well as any instance properties required.
    </para>
    <para>
      In the following example, we create a PhotoCollection that will
      contain our Photo models:
    </para>
    <programlisting language="javascript">
var PhotoCollection = Backbone.Collection.extend({
    model: Photo
});
</programlisting>
    <para>
      <emphasis role="strong">Getters and Setters</emphasis>
    </para>
    <para>
      There are a few different ways to retrieve a model from a
      collection. The most straight-forward is to use
      <literal>Collection.get()</literal> which accepts a single id as
      follows:
    </para>
    <programlisting language="javascript">
var skiingEpicness = PhotoCollection.get(2);
</programlisting>
    <para>
      Sometimes you may also want to get a model based on its client id.
      The client id is a property that Backbone automatically assigns
      models that have not yet been saved. You can get a model’s client
      id from its <literal>.cid</literal> property.
    </para>
    <programlisting language="javascript">
var mySkiingCrash = PhotoCollection.getByCid(456);
</programlisting>
    <para>
      Backbone Collections don’t have setters as such, but do support
      adding new models via <literal>.add()</literal> and removing
      models via <literal>.remove()</literal>.
    </para>
    <programlisting language="javascript">
var a = new Backbone.Model({ title: 'my vacation'}),
    b = new Backbone.Model({ title: 'my holiday'});

var photoCollection = new PhotoCollection([a,b]);
photoCollection.remove([a,b]);
</programlisting>
    <para>
      <emphasis role="strong">Listening for events</emphasis>
    </para>
    <para>
      As collections represent a group of items, we’re also able to
      listen for <literal>add</literal> and <literal>remove</literal>
      events for when new models are added or removed from the
      collection. Here’s an example:
    </para>
    <programlisting language="javascript">
var PhotoCollection = new Backbone.Collection();
PhotoCollection.bind(&quot;add&quot;, function(photo) {
  console.log(&quot;I liked &quot; + photo.get(&quot;title&quot;) + ' its this one, right? ' + photo.get(&quot;src&quot;));
});

PhotoCollection.add([
  {title: &quot;My trip to Bali&quot;, src: &quot;bali-trip.jpg&quot;},
  {title: &quot;The flight home&quot;, src: &quot;long-flight-oofta.jpg&quot;},
  {title: &quot;Uploading pix&quot;, src: &quot;too-many-pics.jpg&quot;}
]);
</programlisting>
    <para>
      In addition, we’re able to bind a <literal>change</literal> event
      to listen for changes to models in the collection.
    </para>
    <programlisting language="javascript">
PhotoCollection.bind(&quot;change:title&quot;, function(){
    console.log('there have been updates made to this collections titles');
});
</programlisting>
    <para>
      <emphasis role="strong">Fetching models from the server</emphasis>
    </para>
    <para>
      <literal>Collections.fetch()</literal> retrieves a default set of
      models from the server in the form of a JSON array. When this data
      returns, the current collection’s contents will be replaced with
      the contents of the array.
    </para>
    <programlisting language="javascript">
var PhotoCollection = new Backbone.Collection;
PhotoCollection.url = '/photos';
PhotoCollection.fetch();
</programlisting>
    <para>
      Under the covers, <literal>Backbone.sync</literal> is the function
      called every time Backbone tries to read or save models to the
      server. It uses jQuery or Zepto’s ajax implementations to make
      these RESTful requests, however this can be overridden as per your
      needs.
    </para>
    <para>
      In the above example if we wanted to log an event when
      <literal>.sync()</literal> was called, we could do this:
    </para>
    <programlisting language="javascript">
Backbone.sync = function(method, model) {
  console.log(&quot;I've been passed &quot; + method + &quot; with &quot; + JSON.stringify(model));
};
</programlisting>
    <para>
      <emphasis role="strong">Resetting/Refreshing
      Collections</emphasis>
    </para>
    <para>
      Rather than adding or removing models individually, you might
      occasionally wish to update an entire collection at once.
      <literal>Collection.reset()</literal> allows us to replace an
      entire collection with new models as follows:
    </para>
    <programlisting language="javascript">
PhotoCollection.reset([
  {title: &quot;My trip to Scotland&quot;, src: &quot;scotland-trip.jpg&quot;},
  {title: &quot;The flight from Scotland&quot;, src: &quot;long-flight.jpg&quot;},
  {title: &quot;Latest snap of lock-ness&quot;, src: &quot;lockness.jpg&quot;}]);
</programlisting>
  </sect2>
  <sect2 id="underscore-utility-functions">
    <title>Underscore utility functions</title>
    <para>
      As Backbone requires Underscore as a hard dependency, we’re able
      to use many of the utilities it has to offer to aid with our
      application development. Here’s an example of how Underscore’s
      <literal>sortBy()</literal> method can be used to sort a
      collection of photos based on a particular attribute.
    </para>
    <programlisting language="javascript">
var sortedByAlphabet = PhotoCollection.sortBy(function (photo) {
    return photo.get(&quot;title&quot;).toLowerCase();
});
</programlisting>
    <para>
      The complete list of what Underscore can do is beyond the scope of
      this guide, but can be found in its official
      <ulink url="http://documentcloud.github.com/underscore/">docs</ulink>.
    </para>
  </sect2>
  <sect2 id="routers">
    <title><a name="routers">Routers</a></title>
    <para>
      In Backbone, routers are used to help manage application state and
      for connecting URLs to application events. This is achieved using
      hash-tags with URL fragments, or using the browser’s pushState and
      History API. Some examples of routes may be seen below:
    </para>
    <programlisting language="javascript">
http://unicorns.com/#whatsup
http://unicorns.com/#search/seasonal-horns/page2
</programlisting>
    <para>
      Note: An application will usually have at least one route mapping
      a URL route to a function that determines what happens when a user
      reaches that particular route. This relationship is defined as
      follows:
    </para>
    <programlisting language="javascript">
&quot;route&quot; : &quot;mappedFunction&quot;
</programlisting>
    <para>
      Let us now define our first controller by extending
      <literal>Backbone.Router</literal>. For the purposes of this
      guide, we’re going to continue pretending we’re creating a photo
      gallery application that requires a GalleryRouter.
    </para>
    <para>
      Note the inline comments in the code example below as they
      continue the rest of the lesson on routers.
    </para>
    <programlisting language="javascript">
var GalleryRouter = Backbone.Router.extend({
    /* define the route and function maps for this router */
    routes: {
        &quot;about&quot; : &quot;showAbout&quot;,
        /*Sample usage: http://unicorns.com/#about*/

        &quot;photos/:id&quot; : &quot;getPhoto&quot;,
        /*This is an example of using a &quot;:param&quot; variable which allows us to match
        any of the components between two URL slashes*/
        /*Sample usage: http://unicorns.com/#photos/5*/

        &quot;search/:query&quot; : &quot;searchPhotos&quot;
        /*We can also define multiple routes that are bound to the same map function,
        in this case searchPhotos(). Note below how we're optionally passing in a
        reference to a page number if one is supplied*/
        /*Sample usage: http://unicorns.com/#search/lolcats*/

        &quot;search/:query/p:page&quot; : &quot;searchPhotos&quot;,
        /*As we can see, URLs may contain as many &quot;:param&quot;s as we wish*/
        /*Sample usage: http://unicorns.com/#search/lolcats/p1*/

        &quot;photos/:id/download/*imagePath&quot; : &quot;downloadPhoto&quot;,
        /*This is an example of using a *splat. splats are able to match any number of
        URL components and can be combined with &quot;:param&quot;s*/
        /*Sample usage: http://unicorns.com/#photos/5/download/files/lolcat-car.jpg*/

        /*If you wish to use splats for anything beyond default routing, it's probably a good
        idea to leave them at the end of a URL otherwise you may need to apply regular
        expression parsing on your fragment*/

        &quot;*other&quot; : &quot;defaultRoute&quot;
        /*This is a default route that also uses a *splat. Consider the
        default route a wildcard for URLs that are either not matched or where
        the user has incorrectly typed in a route path manually*/
        /*Sample usage: http://unicorns.com/#anything*/

    },

    showAbout: function(){
    },

    getPhoto: function(id){
        /*
        Note that the id matched in the above route will be passed to this function
        */
        console.log(&quot;You are trying to reach photo &quot; + id);
    },

    searchPhotos: function(query, page){
        console.log(&quot;Page number: &quot; + page + &quot; of the results for &quot; + query);
    },

    downloadPhoto: function(id, path){
    },

    defaultRoute: function(other){
        console.log(&quot;Invalid. You attempted to reach:&quot; + other);
    }
});

/* Now that we have a router setup, remember to instantiate it*/

var myGalleryRouter = new GalleryRouter();
</programlisting>
    <para>
      As of Backbone 0.5+, it’s possible to opt-in for HTML5 pushState
      support via <literal>window.history.pushState</literal>. This
      permits you to define routes such as
      http://www.scriptjunkie.com/just/an/example. This will be
      supported with automatic degradation when a user’s browser doesn’t
      support pushState. For the purposes of this tutorial, we’ll use
      the hashtag method.
    </para>
    <sect3 id="backbone.history">
      <title>Backbone.history</title>
      <para>
        Next, we need to initialize <literal>Backbone.history</literal>
        as it handles <literal>hashchange</literal> events in our
        application. This will automatically handle routes that have
        been defined and trigger callbacks when they’ve been accessed.
      </para>
      <para>
        The <literal>Backbone.history.start()</literal> method will
        simply tell Backbone that it’s OK to begin monitoring all
        <literal>hashchange</literal> events as follows:
      </para>
      <programlisting language="javascript">
Backbone.history.start();
Router.navigate();
</programlisting>
      <para>
        As an aside, if you would like to save application state to the
        URL at a particular point you can use the
        <literal>.navigate()</literal> method to achieve this. It simply
        updates your URL fragment without the need to trigger the
        <literal>hashchange</literal> event:
      </para>
      <programlisting language="javascript">
/*Lets imagine we would like a specific fragment for when a user zooms into a photo*/
zoomPhoto: function(factor){
    this.zoom(factor); //imagine this zooms into the image
    this.navigate(&quot;zoom/&quot; + factor); //updates the fragment for us, but doesn't trigger the route
}
</programlisting>
      <para>
        It is also possible for <literal>Router.navigate()</literal> to
        trigger the route as well as updating the URL fragment.
      </para>
      <programlisting language="javascript">
zoomPhoto: function(factor){
    this.zoom(factor); //imagine this zooms into the image
    this.navigate(&quot;zoom/&quot; + factor, true); //updates the fragment for us and triggers the route
}
</programlisting>
    </sect3>
  </sect2>
  <sect2 id="namespacing">
    <title><a name="namespacing">Namespacing</a></title>
    <para>
      When learning how to use Backbone, an important and commonly
      overlooked area by tutorials is namespacing. If you already have
      experience with namespacing in JavaScript, the following section
      will provide some advice on how to specifically apply concepts you
      know to Backbone, however I will also be covering explanations for
      beginners to ensure everyone is on the same page.
    </para>
    <sect3 id="what-is-namespacing">
      <title>What is namespacing?</title>
      <para>
        The basic idea around namespacing is to avoid collisions with
        other objects or variables in the global namespace. They’re
        important as it’s best to safeguard your code from breaking in
        the event of another script on the page using the same variable
        names as you are. As a good <quote>citizen</quote> of the global
        namespace, it’s also imperative that you do your best to
        similarly not prevent other developer’s scripts executing due to
        the same issues.
      </para>
      <para>
        JavaScript doesn’t really have built-in support for namespaces
        like other languages, however it does have closures which can be
        used to achieve a similar effect.
      </para>
      <para>
        In this section we’ll be taking a look shortly at some examples
        of how you can namespace your models, views, routers and other
        components specifically. The patterns we’ll be examining are:
      </para>
      <itemizedlist>
        <listitem>
          <para>
            Single global variables
          </para>
        </listitem>
        <listitem>
          <para>
            Object Literals
          </para>
        </listitem>
        <listitem>
          <para>
            Nested namespacing
          </para>
        </listitem>
      </itemizedlist>
      <para>
        <emphasis role="strong">Single global variables</emphasis>
      </para>
      <para>
        One popular pattern for namespacing in JavaScript is opting for
        a single global variable as your primary object of reference. A
        skeleton implementation of this where we return an object with
        functions and properties can be found below:
      </para>
      <programlisting language="javascript">
var myApplication = (function(){
    function(){
      // ...
    },
    return {
      // ...
    }
})();
</programlisting>
      <para>
        You’ve probably seen this technique before. A Backbone-specific
        example might look like this:
      </para>
      <programlisting language="javascript">
var myViews = (function(){
    return {
        PhotoView: Backbone.View.extend({ .. }),
        GalleryView: Backbone.View.extend({ .. }),
        AboutView: Backbone.View.extend({ .. });
        //etc.
    };
})();
</programlisting>
      <para>
        Here we can return a set of views, but the same technique could
        return an entire collection of models, views and routers
        depending on how you decide to structure your application.
        Although this works for certain situations, the biggest
        challenge with the single global variable pattern is ensuring
        that no one else has used the same global variable name as you
        have in the page.
      </para>
      <para>
        One solution to this problem, as mentioned by Peter Michaux, is
        to use prefix namespacing. It’s a simple concept at heart, but
        the idea is you select a common prefix name (in this example,
        <literal>myApplication_</literal>) and then define any methods,
        variables or other objects after the prefix.
      </para>
      <programlisting language="javascript">
var myApplication_photoView = Backbone.View.extend({}),
myApplication_galleryView = Backbone.View.extend({});
</programlisting>
      <para>
        This is effective from the perspective of trying to lower the
        chances of a particular variable existing in the global scope,
        but remember that a uniquely named object can have the same
        effect. This aside, the biggest issue with the pattern is that
        it can result in a large number of global objects once your
        application starts to grow.
      </para>
      <para>
        For more on Peter’s views about the single global variable
        pattern, read his
        <ulink url="http://michaux.ca/articles/javascript-namespacing">excellent
        post on them</ulink>.
      </para>
      <para>
        Note: There are several other variations on the single global
        variable pattern out in the wild, however having reviewed quite
        a few, I felt the prefixing approach applied best to Backbone.
      </para>
      <para>
        <emphasis role="strong">Object Literals</emphasis>
      </para>
      <para>
        Object Literals have the advantage of not polluting the global
        namespace but assist in organizing code and parameters
        logically. They’re beneficial if you wish to create easily
        readable structures that can be expanded to support deep
        nesting. Unlike simple global variables, Object Literals often
        also take into account tests for the existence of a variable by
        the same name, which helps reduce the chances of collision.
      </para>
      <para>
        This example demonstrates two ways you can check to see if a
        namespace already exists before defining it. I commonly use
        Option 2.
      </para>
      <programlisting language="javascript">
/*Doesn't check for existence of myApplication*/
var myApplication = {};

/*
Does check for existence. If already defined, we use that instance.
Option 1: if(!myApplication) myApplication = {};
Option 2: var myApplication = myApplication || {};
We can then populate our object literal to support models, views and collections (or any data, really):
*/

var myApplication = {
    models : {},
    views : {
        pages : {}
    },
    collections : {}
};
</programlisting>
      <para>
        One can also opt for adding properties directly to the namespace
        (such as your views, in the following example):
      </para>
      <programlisting language="javascript">
var myGalleryViews = myGalleryViews || {};
myGalleryViews.photoView = Backbone.View.extend({});
myGalleryViews.galleryView = Backbone.View.extend({});
</programlisting>
      <para>
        The benefit of this pattern is that you’re able to easily
        encapsulate all of your models, views, routers etc. in a way
        that clearly separates them and provides a solid foundation for
        extending your code.
      </para>
      <para>
        This pattern has a number of benefits. It’s often a good idea to
        decouple the default configuration for your application into a
        single area that can be easily modified without the need to
        search through your entire codebase just to alter it. Here’s an
        example of a hypothetical object literal that stores application
        configuration settings:
      </para>
      <programlisting language="javascript">
var myConfig = {
    language: 'english',
    defaults: {
        enableGeolocation: true,
        enableSharing: false,
        maxPhotos: 20
    },
    theme: {
        skin: 'a',
        toolbars: {
            index: 'ui-navigation-toolbar',
            pages: 'ui-custom-toolbar'
        }
    }
}
</programlisting>
      <para>
        Note that there are really only minor syntactical differences
        between the Object Literal pattern and a standard JSON data set.
        If for any reason you wish to use JSON for storing your
        configurations instead (e.g. for simpler storage when sending to
        the back-end), feel free to.
      </para>
      <para>
        For more on the Object Literal pattern, I recommend reading
        Rebecca Murphey’s
        <ulink url="http://blog.rebeccamurphey.com/2009/10/15/using-objects-to-organize-your-code">excellent
        article on the topic</ulink>.
      </para>
      <para>
        <emphasis role="strong">Nested namespacing</emphasis>
      </para>
      <para>
        An extension of the Object Literal pattern is nested
        namespacing. It’s another common pattern used that offers a
        lower risk of collision due to the fact that even if a top-level
        namespace already exists, it’s unlikely the same nested children
        do. For example, Yahoo’s YUI uses the nested object namespacing
        pattern extensively:
      </para>
      <programlisting language="javascript">
YAHOO.util.Dom.getElementsByClassName('test');
</programlisting>
      <para>
        Yahoo’s YUI uses the nested object namespacing pattern regularly
        and even DocumentCloud (the creators of Backbone) use the nested
        namespacing pattern in their main applications. A sample
        implementation of nested namespacing with Backbone may look like
        this:
      </para>
      <programlisting language="javascript">
var galleryApp = galleryApp || {};

// perform similar check for nested children
galleryApp.routers = galleryApp.routers || {};
galleryApp.model = galleryApp.model || {};
galleryApp.model.special = galleryApp.model.special || {};

// routers
galleryApp.routers.Workspace = Backbone.Router.extend({});
galleryApp.routers.PhotoSearch = Backbone.Router.extend({});

// models
galleryApp.model.Photo = Backbone.Model.extend({});
galleryApp.model.Comment = Backbone.Model.extend({});

// special models
galleryApp.model.special.Admin = Backbone.Model.extend({});
</programlisting>
      <para>
        This is readable, clearly organized, and is a relatively safe
        way of namespacing your Backbone application. The only real
        caveat however is that it requires your browser’s JavaScript
        engine to first locate the galleryApp object, then dig down
        until it gets to the function you’re calling. However,
        developers such as Juriy Zaytsev (kangax) have tested and found
        the performance differences between single object namespacing vs
        the <quote>nested</quote> approach to be quite negligible.
      </para>
      <para>
        <emphasis role="strong">Recommendation</emphasis>
      </para>
      <para>
        Reviewing the namespace patterns above, the option that I prefer
        when writing Backbone applications is nested object namespacing
        with the object literal pattern.
      </para>
      <para>
        Single global variables may work fine for applications that are
        relatively trivial. However, larger codebases requiring both
        namespaces and deep sub-namespaces require a succinct solution
        that’s both readable and scalable. I feel this pattern achieves
        both of these objectives and is a good choice for most Backbone
        development.
      </para>
    </sect3>
  </sect2>
  <sect2 id="additional-tips">
    <title><a name="additional-tips">Additional Tips</a></title>
    <sect3 id="automated-backbone-scaffolding">
      <title>Automated Backbone Scaffolding</title>
      <para>
        Scaffolding can assist in expediting how quickly you can begin a
        new application by creating the basic files required for a
        project automatically. If you enjoy the idea of automated MVC
        scaffolding using Backbone, I’m happy to recommend checking out
        a tool called
        <ulink url="https://github.com/brunch/brunch">Brunch</ulink>.
      </para>
      <para>
        It works very well with Backbone, Underscore, jQuery and
        CoffeeScript and is even used by companies such as Red Bull and
        Jim Beam. You may have to update any third party dependencies
        (e.g. latest jQuery or Zepto) when using it, but other than that
        it should be fairly stable to use right out of the box.
      </para>
      <para>
        Brunch can be installed via the nodejs package manager and is
        easy to get started with. If you happen to use Vim or Textmate
        as your editor of choice, you’ll be happy to know that there are
        Brunch bundles available for both.
      </para>
    </sect3>
    <sect3 id="is-there-a-limit-to-the-number-of-routers-i-should-be-using">
      <title>Is there a limit to the number of routers I should be
      using?</title>
      <para>
        Andrew de Andrade has pointed out that DocumentCloud themselves
        usually only use a single router in most of their applications.
        You’re very likely to not require more than one or two routers
        in your own projects as the majority of your application routing
        can be kept organized in a single controller without it getting
        unwieldy.
      </para>
    </sect3>
    <sect3 id="is-backbone-too-small-for-my-applications-needs">
      <title>Is Backbone too small for my application’s needs?</title>
      <para>
        If you find yourself unsure of whether or not your application
        is too large to use Backbone, I recommend reading my post on
        building large-scale jQuery &amp; JavaScript applications or
        reviewing my slides on client-side MVC architecture options. In
        both, I cover alternative solutions and my thoughts on the
        suitability of current MVC solutions for scaled application
        development.
      </para>
      <para>
        Backbone can be used for building both trivial and complex
        applications as demonstrated by the many examples Ashkenas has
        been referencing in the Backbone documentation. As with any MVC
        framework however, it’s important to dedicate time towards
        planning out what models and views your application really
        needs. Diving straight into development without doing this can
        result in either spaghetti code or a large refactor later on and
        it’s best to avoid this where possible.
      </para>
      <para>
        At the end of the day, the key to building large applications is
        not to build large applications in the first place. If you
        however find Backbone doesn’t cut it for your requirements I
        strongly recommend checking out JavaScriptMVC or SproutCore as
        these both offer a little more than Backbone out of the box.
        Dojo and Dojo Mobile may also be of interest as these have also
        been used to build significantly complex apps by other
        developers.
      </para>
    </sect3>
  </sect2>
</sect1>
<sect1 id="restful-applications">
  <title>## <a name="restfulapps">RESTful Applications</a></title>
  <para>
  </para>
</sect1>
<sect1 id="building-restful-applications-with-backbone">
  <title><a name="restful">Building RESTful applications with
  Backbone</a></title>
  <para>
    In this section of the book, we’re going to take a look at
    developing RESTful applications using Backbone.js and modern
    technology stacks. When the data for your back-end is exposed
    through a purely RESTful API, tasks such as retrieving (GET),
    creating (POST), updating (PUT) and deleting (DELETE) models are
    made easy through Backbone’s Model API. This API is so intuitive in
    fact that switching from storing records in a local data-store (e.g
    localStorage) to a database/noSQL data-store is a lot simpler than
    you may think.
  </para>
</sect1>
<sect1 id="stack-1-building-a-backbone-app-with-node.js-express-mongoose-and-mongodb">
  <title><a name="stack1">Stack 1: Building A Backbone App With Node.js,
  Express, Mongoose and MongoDB</a></title>
  <para>
    The first stack we’ll be looking at is:
  </para>
  <itemizedlist>
    <listitem>
      <para>
        <ulink url="nodejs.org">Node.js</ulink>
      </para>
    </listitem>
    <listitem>
      <para>
        <ulink url="http://expressjs.com/">Express</ulink>
      </para>
    </listitem>
    <listitem>
      <para>
        <ulink url="http://mongoosejs.com/">Mongoose</ulink>
      </para>
    </listitem>
    <listitem>
      <para>
        and <ulink url="http://www.mongodb.org/">MongoDB</ulink>
      </para>
    </listitem>
  </itemizedlist>
  <para>
    with <ulink url="http://jade-lang.com/">Jade</ulink> used optionally
    as a view/templating engine.
  </para>
  <sect2 id="reviewing-the-stack">
    <title>Reviewing the stack</title>
    <para>
      As you may know, node.js is an event-driven platform (built on the
      <ulink url="http://code.google.com/apis/v8/design.html">V8</ulink>
      runtime), designed for writing fast, scalable network
      applications. It’s reasonably lightweight, efficient and great for
      real-time applications that are data-intensive.
    </para>
    <para>
      Express is a small web-development framework written with node.js,
      based on <ulink url="http://www.sinatrarb.com/">Sinatra</ulink>.
      It supports a number of useful features such as intuitive views,
      robust routing and a focus on high performance.
    </para>
    <para>
      Next on the list are MongoDB and Mongoose. MongoDB is an
      open-source, document-oriented database store designed with
      scalability and agility in mind. As a
      <ulink url="http://en.wikipedia.org/wiki/NoSQL">noSQL</ulink>
      database, rather than storing data in tables and rows (something
      we’re very used to doing with relational databases), with MongoDB
      we instead store JSON-like documents using dynamic schemas. One of
      the goals of Mongo is to try bridging the gap between key-value
      stores (speed, scalability) and
      <ulink url="http://en.wikipedia.org/wiki/Relational_database">relational</ulink>
      databases (rich functionality).
    </para>
    <para>
      Mongoose is a JavaScript library that simplifies how we interact
      with Mongo. Like Express, it’s designed to work within the node.js
      environment and tries to solve some of the complexities with
      asynchronous data storage by offering a more user-friendly API. It
      also adds chaining features into the mix, allowing for a slightly
      more expressive way of dealing with our data.
    </para>
    <para>
      Jade is a template engine influenced by Haml (which we’ll be
      looking at later). It’s implemented with JavaScript (and also runs
      under node). In addition to supporting Express out of the box, it
      boasts a number of useful features including support for mixins,
      includes, caching, template inheritance and much more. Whilst
      abstractions like Jade certainly aren’t for everyone, our
      practical will cover working both with and without it.
    </para>
  </sect2>
  <sect2 id="practical">
    <title>Practical</title>
    <para>
      For this practical, we’re going to once again look at extending
      the popular Backbone Todo application. Rather than relying on
      localStorage for data persistence, we’re going to switch to
      storing Todos in a MongoDB document-store instead. The code for
      this practical can be found in
      <literal>practicals\stacks\option2</literal>
    </para>
    <para>
      <emphasis role="strong">app.js</emphasis>
    </para>
    <para>
      (See
      <ulink url="https://github.com/addyosmani/backbone-boilerplates/blob/master/option2/app.js">here</ulink>
      for the source)
    </para>
    <para>
      We must first include the node dependencies required by our
      application. These are Express, Mongoose and Path (a module
      containing utilities for dealing with file paths.
    </para>
    <programlisting language="javascript">
var application_root = __dirname,
  express = require(&quot;express&quot;),
  path = require(&quot;path&quot;),
  mongoose = require('mongoose');
</programlisting>
    <para>
      Next, create a new Express server.
      <literal>express.createServer()</literal> is a simple way of
      creating an instance of express.HTTPServer, which we’ll be using
      to pass in our routes.
    </para>
    <programlisting language="javascript">
var app = express.createServer();
</programlisting>
    <para>
      After this, connect Mongoose up to a database (in our case,
      localhost should suffice). Should you require the ability to pass
      in authentication information, here’s a sample containing all of
      the supported URL parameters:
      <literal>mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database][?options]]</literal>
    </para>
    <programlisting language="javascript">
mongoose.connect('mongodb://localhost/my_database');
</programlisting>
    <para>
      A Mongoose model for any Todo item can now be easily defined by
      passing a schema instance to <literal>mongoose.model</literal>. In
      our case the schema covers a Todo item’s <literal>text</literal>
      content, its <literal>done</literal> state and
      <literal>order</literal> position in the overall Todo list.
    </para>
    <programlisting language="javascript">
var Todo = mongoose.model('Todo', new mongoose.Schema({
  text: String,
  done: Boolean,
  order: Number
}));
</programlisting>
    <para>
      The <literal>configure()</literal> methods allows us to setup what
      we need for the current environment with our Express server. Note
      that lower down in the configuration are two view/view related
      lines. The last one explicitly sets the viewing/templating engine
      to be used as Jade
      <literal>app.set('view engine', 'jade')</literal>. We can avoid
      these if we wish to use plain HTML/JS for our templates instead.
    </para>
    <programlisting language="javascript">
app.configure(function(){
  // the bodyParser middleware parses JSON request bodies
  app.use(express.bodyParser());
  app.use(express.methodOverride());
  app.use(app.router);
  app.use(express.static(path.join(application_root, &quot;public&quot;)));
  app.use(express.errorHandler({ dumpExceptions: true, showStack: true }));
  app.set('views', path.join(application_root, &quot;views&quot;));
  app.set('view engine', 'jade')
});
</programlisting>
    <para>
      Should you prefer to switch out Jade for an alternative view
      engine, this can be done fairly trivially. See the section under
      <quote>Templating</quote> here:
      https://github.com/joyent/node/wiki/modules. For example, to
      switch to EJS, you would simply write
      <literal>app.set('view engine', 'ejs')</literal>
    </para>
    <para>
      Express makes use of common HTTP verbs (get, put, post etc.) to
      provide easy to use, expressive routing API based on CRUD (Create,
      Read, Update and Delete). Below for example, we can define what
      happens when the browser requests the root <quote>/</quote>. As a
      trivial route in this application, it doesn’t do anything
      particularly exciting, however getters typically read or retrieve
      data.
    </para>
    <programlisting language="javascript">
app.get('/', function(req, res){
  res.send('Hello World');
});
</programlisting>
    <para>
      Onto something a little more useful and in our next route,
      navigating to <quote>/todo</quote> will actually render our Jade
      view <quote>todo.jade</quote>, as seen in the callback. Additional
      configuration values can be passed as the second parameter, such
      as the custom title specified below.
    </para>
    <programlisting language="javascript">
app.get('/todo', function(req, res){
  res.render('todo', {title: &quot;Our sample application&quot;});
});
</programlisting>
    <para>
      Next, we can see the first of our <quote>/api/</quote> routes.
    </para>
    <programlisting language="javascript">
app.get('/api/todos', function(req, res){
  return Todo.find(function(err, todos) {
    return res.send(todos);
  });
});
</programlisting>
    <para>
      The callback to our next route supports querying for todos based
      on a specific ID. The route string itself (once compiled) will be
      converted from <quote>/api/todos/:id</quote> to a regular
      expression. As you might have guessed, this is a hint that routes
      can also be regular expression literals if we wished to do
      something more complex.
    </para>
    <programlisting language="javascript">
app.get('/api/todos/:id', function(req, res){
  return Todo.findById(req.params.id, function(err, todo) {
    if (!err) {
      return res.send(todo);
    }
  });
});
</programlisting>
    <para>
      Similarly, we want to support updating todos based on a specific
      ID as well. The following allows us to query a todo by ID and then
      update the values of it’s three attributes (text, done, order)
      easily.
    </para>
    <programlisting language="javascript">
app.put('/api/todos/:id', function(req, res){
  return Todo.findById(req.params.id, function(err, todo) {
    todo.text = req.body.text;
    todo.done = req.body.done;
    todo.order = req.body.order;
    return todo.save(function(err) {
      if (!err) {
        console.log(&quot;updated&quot;);
      }
      return res.send(todo);
    });
  });
});
</programlisting>
    <para>
      We’ve so far covered requesting todos and updating them, but a
      core part of the application requires us to insert (or add) new
      todos to our data-store. Below we can create new <code>Todo</code>
      models and simply save them.
    </para>
    <programlisting language="javascript">
app.post('/api/todos', function(req, res){
  var todo;
  todo = new Todo({
    text: req.body.text,
    done: req.body.done,
    order: req.body.order
  });
  todo.save(function(err) {
    if (!err) {
      return console.log(&quot;created&quot;);
    }
  });
  return res.send(todo);
});
</programlisting>
    <para>
      We of course also want to support deleting todos (e.g if a todo
      has been <quote>cleared</quote>, it should be deleted). This also
      works based on a specific todo ID.
    </para>
    <programlisting language="javascript">
app.delete('/api/todos/:id', function(req, res){
  return Todo.findById(req.params.id, function(err, todo) {
    return todo.remove(function(err) {
      if (!err) {
        console.log(&quot;removed&quot;);
        return res.send('')
      }
    });
  });
});
</programlisting>
    <para>
      Finally, this last line is to ensure we’re only listening on the
      port app.js is running.
    </para>
    <programlisting language="javascript">
app.listen(3000);
</programlisting>
    <para>
      <emphasis role="strong">script.js - updating our Backbone.js
      app</emphasis>
    </para>
    <para>
      In the <literal>/public/js</literal> folder of options 1 (HTML
      templates) and 2 (Jade) for the practical, you’ll find a version
      of the Backbone Todo app originally by Jerome Gravel-Niquet. Let’s
      pay attention to
      <ulink url="https://github.com/addyosmani/backbone-boilerplates/blob/master/option2/public/js/script.js">script.js</ulink>.
      In order to change the application to work with our new back-end,
      we’ll need to make some very minor changes to this.
    </para>
    <para>
      Reviewing <literal>window.TodoList</literal> (a Backbone
      Collection), you’ll notice that it has a property called
      <literal>localStorage</literal>, which uses the Backbone
      <ulink url="https://github.com/jeromegn/Backbone.localStorage">localStorage</ulink>
      adapter in order to facilitate storing data using the browser’s
      localStorage features.
    </para>
    <programlisting language="javascript">
window.TodoList = Backbone.Collection.extend({

    // Reference to this collection's model.
    model: Todo,

    // Save all of the todo items under the `&quot;todos&quot;` namespace.
    // Typically, this should be a unique name within your application
    localStorage: new Store(&quot;todos&quot;),
</programlisting>
    <para>
      In order to switch it over to our RESTful backend, we’re going to
      make use of the <literal>url</literal> property or function on a
      collection to reference its location on the server. Models inside
      of a collection then use <literal>url</literal> to construct URLs
      of their own. As all of the CRUD for our RESTful API works on the
      base route <quote>/api/todos</quote>, this is the value we set
      <literal>url</literal> to.
    </para>
    <programlisting language="javascript">
    // localStorage: new Store(&quot;todos&quot;),
    url: '/api/todos',
</programlisting>
    <para>
      This is the only change necessary to our existing Backbone
      application in order to get things working. Pretty easy, right?
    </para>
    <para>
      <emphasis role="strong">todo.jade</emphasis>
    </para>
    <para>
      The Jade templates for our application cover declarative markup
      for both the index (layout.jade) of the application and the main
      Todo container (todo.jade). It also covers the script-tag
      templates used for rendering each new Todo item that’s added.
    </para>
    <programlisting language="html">
// Todo App Interface

#todoapp
  .title
    h1 Todos
  .content
    #create-todo
      input#new-todo(placeholder=&amp;quot;What needs to be done?&amp;quot;, type=&amp;quot;text&amp;quot;)
      span.ui-tooltip-top(style=&amp;quot;display:none;&amp;quot;) Press Enter to save this task
    #todos
      ul#todo-list
    #todo-stats


// Templates
script#item-template(type=&amp;quot;text/template&amp;quot;)
  &amp;lt;div class=&amp;quot;todo &amp;lt;%= done ? 'done' : '' %&amp;gt;&amp;quot;&amp;gt;
  .display
    &amp;lt;input class=&amp;quot;check&amp;quot; type=&amp;quot;checkbox&amp;quot; &amp;lt;%= done ? 'checked=&amp;quot;checked&amp;quot;' : '' %&amp;gt; /&amp;gt;
    .todo-text
    span#todo-destroy
  .edit
    input.todo-input(type=&amp;quot;text&amp;quot;, &amp;quot;value&amp;quot;=&amp;quot;&amp;quot;)
  &amp;lt;/div&amp;gt;

script#stats-template(type=&amp;quot;text/template&amp;quot;)
  &amp;lt;% if (total) { %&amp;gt;
  span.todo-count
    span.number &amp;lt;%= remaining %&amp;gt;
    span.word &amp;lt;%= remaining == 1 ? 'item' : 'items' %&amp;gt;
    | left.
  &amp;lt;% } %&amp;gt;
  &amp;lt;% if (done) { %&amp;gt;
  span.todo-clear
    a(href=&amp;quot;#&amp;quot;)
      | Clear
      span.number-done &amp;lt;%= done %&amp;gt;
      | completed
      span.word-done &amp;lt;%= done == 1 ? 'item' : 'items' %&amp;gt;
  &amp;lt;% } %&amp;gt;
</programlisting>
    <para>
      <emphasis role="strong">layout.jade</emphasis>
    </para>
    <programlisting language="html">
!!! 5
//if lt IE 6
  &amp;lt;html class=&amp;quot;no-js ie6 oldie&amp;quot; lang=&amp;quot;en&amp;quot;&amp;gt;
//if IE 7
  &amp;lt;html class=&amp;quot;no-js ie7 oldie&amp;quot; lang=&amp;quot;en&amp;quot;&amp;gt;
//if IE 8
  &amp;lt;html class=&amp;quot;no-js ie8 oldie&amp;quot; lang=&amp;quot;en&amp;quot;&amp;gt;
//if gt IE 8
  &amp;lt;!--&amp;gt; &amp;lt;html class=&amp;quot;no-js&amp;quot; lang=&amp;quot;en&amp;quot;&amp;gt; &amp;lt;!--
head
  meta(charset=&amp;quot;utf-8&amp;quot;)
  meta(http-equiv=&amp;quot;X-UA-Compatible&amp;quot;, content=&amp;quot;IE=edge,chrome=1&amp;quot;)

  title=title
  meta(name=&amp;quot;description&amp;quot;, content=&amp;quot;&amp;quot;)
  meta(name=&amp;quot;author&amp;quot;, content=&amp;quot;&amp;quot;)
  meta(name=&amp;quot;viewport&amp;quot;, content=&amp;quot;width=device-width,initial-scale=1&amp;quot;)

  // CSS concatenated and minified via ant build script
  link(rel=&amp;quot;stylesheet&amp;quot;, href=&amp;quot;css/style.css&amp;quot;)
  // end CSS

  script(src=&amp;quot;js/libs/modernizr-2.0.6.min.js&amp;quot;)
body

  #container
    header
    #main(role=&amp;quot;main&amp;quot;)!=body
    footer
  //! end of #container

  script(src=&amp;quot;//ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js&amp;quot;)
  script
    window.jQuery || document.write('&amp;lt;script src=&amp;quot;js/libs/jquery-1.6.2.min.js&amp;quot;&amp;gt;&amp;lt;\\/script&amp;gt;')

  // scripts concatenated and minified via ant build script
  script(src=&amp;quot;js/mylibs/underscore.js&amp;quot;)
  script(src=&amp;quot;js/mylibs/backbone.js&amp;quot;)
  script(defer, src=&amp;quot;js/plugins.js&amp;quot;)
  script(defer, src=&amp;quot;js/script.js&amp;quot;)
  // end scripts

  // Change UA-XXXXX-X to be your site's ID
  script
    window._gaq = [['_setAccount','UAXXXXXXXX1'],['_trackPageview'],['_trackPageLoadTime']];
    Modernizr.load({load: ('https:' == location.protocol ? '//ssl' : '//www') + '.google-analytics.com/ga.js'});

  //if lt IE 7
    script(src=&amp;quot;//ajax.googleapis.com/ajax/libs/chrome-frame/1.0.3/CFInstall.min.js&amp;quot;)
    script
      window.attachEvent('onload',function(){CFInstall.check({mode:'overlay'})})
&amp;lt;/html&amp;gt;
</programlisting>
    <para>
      <emphasis role="strong">static.html</emphasis>
    </para>
    <para>
      Alternatively, a static version of our index which doesn’t rely on
      Jade can be put together as follows. See
      <ulink url="https://github.com/addyosmani/backbone-boilerplates/blob/master/option1/public/static.html">here</ulink>
      for the complete file or below for a sample.
    </para>
    <programlisting language="html">
 &amp;lt;div id=&amp;quot;container&amp;quot;&amp;gt;
    &amp;lt;div id=&amp;quot;main&amp;quot; role=&amp;quot;main&amp;quot;&amp;gt;

      &amp;lt;!-- Todo App Interface--&amp;gt;

      &amp;lt;div id=&amp;quot;todoapp&amp;quot;&amp;gt;
        &amp;lt;div class=&amp;quot;title&amp;quot;&amp;gt;
          &amp;lt;h1&amp;gt;Todos&amp;lt;/h1&amp;gt;
        &amp;lt;/div&amp;gt;

        &amp;lt;div class=&amp;quot;content&amp;quot;&amp;gt;
          &amp;lt;div id=&amp;quot;create-todo&amp;quot;&amp;gt;
            &amp;lt;input id=&amp;quot;new-todo&amp;quot; placeholder=&amp;quot;What needs to be done?&amp;quot; type=
            &amp;quot;text&amp;quot; /&amp;gt;&amp;lt;span style=&amp;quot;display:none;&amp;quot; class=&amp;quot;ui-tooltip-top&amp;quot;&amp;gt;Press Enter to
            save this task&amp;lt;/span&amp;gt;
          &amp;lt;/div&amp;gt;

          &amp;lt;div id=&amp;quot;todos&amp;quot;&amp;gt;
            &amp;lt;ul id=&amp;quot;todo-list&amp;quot;&amp;gt;&amp;lt;/ul&amp;gt;
          &amp;lt;/div&amp;gt;

          &amp;lt;div id=&amp;quot;todo-stats&amp;quot;&amp;gt;&amp;lt;/div&amp;gt;
        &amp;lt;/div&amp;gt;
      &amp;lt;/div&amp;gt;


    &amp;lt;!-- Templates--&amp;gt;

      &amp;lt;script id=&amp;quot;item-template&amp;quot; type=&amp;quot;text/template&amp;quot;&amp;gt;
      &amp;lt;div class=&amp;quot;todo &amp;lt;%= done ? 'done' : '' %&amp;gt;&amp;quot;&amp;gt;
      &amp;lt;div class=&amp;quot;display&amp;quot;&amp;gt;&amp;lt;input class=&amp;quot;check&amp;quot; type=&amp;quot;checkbox&amp;quot; &amp;lt;%= done ? 'checked=&amp;quot;checked&amp;quot;' : '' %&amp;gt; /&amp;gt;
      &amp;lt;div class=&amp;quot;todo-text&amp;quot;&amp;gt;&amp;lt;/div&amp;gt;&amp;lt;span id=&amp;quot;todo-destroy&amp;quot;&amp;gt;&amp;lt;/span&amp;gt;&amp;lt;/div&amp;gt;&amp;lt;div class=&amp;quot;edit&amp;quot;&amp;gt;&amp;lt;input type=&amp;quot;text&amp;quot; value=&amp;quot;&amp;quot; class=&amp;quot;todo-input&amp;quot;/&amp;gt;&amp;lt;/div&amp;gt;&amp;lt;/div&amp;gt;
      &amp;lt;/script&amp;gt;

      &amp;lt;script id=&amp;quot;stats-template&amp;quot; type=&amp;quot;text/template&amp;quot;&amp;gt;
      &amp;lt;% if (total) { %&amp;gt;
      &amp;lt;span class=&amp;quot;todo-count&amp;quot;&amp;gt;&amp;lt;span class=&amp;quot;number&amp;quot;&amp;gt;&amp;lt;%= remaining %&amp;gt; &amp;lt;/span&amp;gt;&amp;lt;span class=&amp;quot;word&amp;quot;&amp;gt;&amp;lt;%= remaining == 1 ? 'item' : 'items' %&amp;gt;&amp;lt;/span&amp;gt; left.
      &amp;lt;/span&amp;gt;&amp;lt;% } %&amp;gt;
      &amp;lt;% if (done) { %&amp;gt;
      &amp;lt;span class=&amp;quot;todo-clear&amp;quot;&amp;gt;&amp;lt;a href=&amp;quot;#&amp;quot;&amp;gt; Clear
      &amp;lt;span class=&amp;quot;number-done&amp;quot;&amp;gt;&amp;lt;%= done %&amp;gt;&amp;lt;/span&amp;gt; completed
      &amp;lt;span class=&amp;quot;word-done&amp;quot;&amp;gt;&amp;lt;%= done == 1 ? 'item' : 'items' %&amp;gt;&amp;lt;/span&amp;gt;&amp;lt;/a&amp;gt;&amp;lt;/span&amp;gt;&amp;lt;% } %&amp;gt;
      &amp;lt;/script&amp;gt;

    &amp;lt;/div&amp;gt;
  &amp;lt;/div&amp;gt;

  &amp;lt;!--! end of #container--&amp;gt;
</programlisting>
  </sect2>
  <sect2 id="practical-setup">
    <title>Practical Setup</title>
    <para>
      We’ve now gone through the major points of developing a RESTful
      backend using Node.js, Express and Mongoose. Next, let’s make sure
      you can get your environment setup to run the updated Todo app.
    </para>
    <sect3 id="mongodb">
      <title>MongoDB</title>
      <para>
        Once you’ve downloaded
        <ulink url="http://www.mongodb.org/downloads">MongoDB</ulink>,
        you’ll need to complete two steps to get it up and running.
      </para>
      <para>
        <emphasis role="strong">Data directories</emphasis>
      </para>
      <para>
        MongoDB stores data in the bin/data/db folder but won’t actually
        create this directory for you. Navigate to where you’ve
        downloaded and extracted MongoDB and run the following from
        terminal:
      </para>
      <programlisting language="html">
sudo mkdir -p /data/db/
sudo chown `id -u` /data/db
</programlisting>
      <para>
        <emphasis role="strong">Running and connecting to your
        server</emphasis>
      </para>
      <para>
        Once this is done, open up two terminal windows.
      </para>
      <para>
        In the first, <literal>cd</literal> to your MongoDB bin
        directory or type in the complete path to it. You’ll need to
        start <cpde>mongod`.
      </para>
      <programlisting language="html">
$ ./bin/mongod
</programlisting>
      <para>
        Next, in the second terminal, start the
        `mongo</code shell which will connect up to localhost by default.

        ```html
        $ ./bin/mongo
        ```

        That's it!.

        ####Express and Mongoose

        Option 1 (HTML) and Option 2 (Jade) of the practical download both come with an install.sh bash script. This allows you to easily install Express, Mongoose, Jade (and optionally MongoDB if you prefer to) through npm (the node package manager).

        * Make sure you have Node.js installed. If not, you can grab it [here](http://nodejs.org/#download)
        * Next run `$ ./install.sh` at the terminal to install the rest of our dependencies. To see the exact contents of the install.sh file, see below:

        **install.sh**

        ```html
        #!/bin/bash
        npm install express
        npm install mongodb --mongodb:native
        npm install mongoose
        npm install jade
        ```


        * After you've installed all of the dependencies for the stack, we can get to cloning the repo containing our practicals and running them. Start by running the below lines:

        ```html
        git clone git://github.com/addyosmani/backbone-boilerplates.git
        cd option2
        node app.js
        ```

        For option1 (without Jade), simply cd into option1 and run `node app.js` from there.

        Finally, either of the example apps can now be accessed by navigating to:

        * Option 1: `http://localhost:3000/static.html`
        * Option 2: `http://localhost:3000/todo`

        That's it! Whilst there's a lot more than can be done to expand on the concepts covered so far, the base we're reviewed should be enough to get you up and running with this stack if you wish to use it with Backbone.


        #<a name="stack2">Building Backbone.js Apps With Ruby, Sinatra,
        MongoDB and Haml</a>
      </para>
    </sect3>
  </sect2>
</sect1>
<sect1 id="introduction-1">
  <title>Introduction</title>
  <para>
    In this chapter we’re going to explore writing Backbone.js
    applications with a Ruby back-end. To assist with this, we’re going
    to use <ulink url="http://www.sinatrarb.com/">Sinatra</ulink> - a
    DSL (domain specific language) for rapidly creating web applications
    in Ruby. Similar to the
    <ulink url="https://github.com/addyosmani/backbone-fundamentals/#stack1">section</ulink>
    on writing an application with Node.js, our server-side language
    (Ruby) will be used to power an API whilst Backbone.js will be the
    client consuming it.
  </para>
</sect1>
<sect1 id="what-is-sinatra">
  <title>What Is Sinatra?</title>
  <para>
    In the past, you’ve likely come across or used
    <ulink url="http://rubyonrails.org">Ruby on Rails</ulink> (RoR) - a
    popular web application framework for the Ruby programming language
    that helps organize applications using the MVC pattern. Sinatra is a
    much smaller, more light-weight alternative to it.
  </para>
  <para>
    Whilst a very basic Rails application may require a more strict
    project structure (such as requiring the use of controllers, views
    and routing etc.), Sinatra doesn’t require as many of these
    dependencies, sacrificing the helpers needed to connect to
    databases, tools to create forms or any of the other utilities Rails
    comes with out of the box.
  </para>
  <para>
    What Sinatra does have is a
    <emphasis role="strong">minimal</emphasis> set of features most
    useful for tying specific URLs and RESTful HTTP actions to blocks of
    Ruby code and returning this code’s output as a response. Sinatra is
    particularly useful for getting projects up and running quickly
    where we don’t have a need for the extra pieces RoR provides.
  </para>
  <para>
    For those who are familiar with more Rails, you probably know that
    it requires a separate routes file to define how an application
    should be responding to requests. These are then piped into the
    relevant models and controllers as needed.
  </para>
  <para>
    Sinatra takes a more straight-forward approach, providing us with
    the most simple path to handling routing. By declaring
    <literal>get</literal>,<literal>post</literal>,
    <literal>put</literal> or <literal>delete</literal> actions, we can
    inform Sinatra to add a new route, which we can then have respond to
    requests.
  </para>
  <para>
    The framework is particularly useful for writing APIs, widgets and
    small-scale applications that can power the backend of a
    client-heavy application. As mentioned, we will be using it to power
    our API.
  </para>
</sect1>
<sect1 id="getting-started-with-sinatra">
  <title>Getting Started With Sinatra</title>
  <para>
    Let’s review how to write and run a very basic Sinatra application.
    As most programming languages and frameworks typically start with
    some variation of <quote>Hello World</quote>, we’ll start with a
    similar example.
  </para>
  <para>
    Note: Before beginning this section, I recommend installing Sinatra
    on your system. A guide to doing this can be found in the
    <link linkend="preq">prerequisites</link> section lower down in the
    article.
  </para>
  <sect2 id="routes">
    <title>Routes</title>
    <para>
      As mentioned, Sinatra allows us to define new routes using HTTP
      actions. Semantically, a route follows quite a simple structure:
    </para>
    <programlisting language="ruby">
&lt;a HTTP action&gt; &lt;the desired route&gt; do
   # some behaviour
end
</programlisting>
    <para>
      A tiny route that outputs a <quote>Hello World</quote>-like
      message when we attempt to <quote>get</quote> the root could thus
      be written as follows:
    </para>
    <programlisting language="ruby">
require 'sinatra'

get '/' do
   &quot;Hello World! Is it me you're looking for?&quot;
end
</programlisting>
    <para>
      To run this snippet, we can can simply save it to a local ’.rb’
      file and execute it as follows:
    </para>
    <programlisting language="ruby">
ruby -rubygems example.rb
</programlisting>
    <para>
      If we now navigated to http://localhost:4567 in our browser we
      could now see the application running successfully.
    </para>
    <para>
      The HTTP verbs we commonly work with when writing RESTful web
      services are: <literal>get</literal>, <literal>post</literal>,
      <literal>delete</literal> and <literal>put</literal>. As we now
      know, all Sinatra routes are basically HTTP actions
      (`<literal>get</literal> etc.) that are paired with a URL-matching
      pattern. We associate a pair of an action and route with code we
      would like sent back to the browser (executed)if the route is
      reached. Sinatra doesn’t enforce much in the way of architectural
      structure, instead relying on simplicity to supporting writing
      powerful APIs.
    </para>
    <para>
      Here’s an example of a skeleton service we could put together
      supporting four common HTTP actions: ruby ``` get
      <quote>/items</quote> do # list all items available end
    </para>
    <para>
      get <quote>/item/:id</quote> do # get a single item end
    </para>
    <para>
      post <quote>/item</quote> do # create a new item end
    </para>
    <para>
      put <quote>/item/:id</quote> do # update an existing item end
    </para>
    <para>
      delete <quote>/item/:id</quote> do # delete an item end ```
    </para>
    <para>
      Sinatra’s routing is both easy for beginners to get started with
      but is also flexible enough for those wishing to define more
      complex routes. As you probably noticed in the above example,
      routes can include named parameters (e.g
      <literal>/item/:id</literal>). We can actually access the content
      of these routes using the <literal>params</literal> hash as
      follows:
    </para>
    <programlisting language="ruby">
get '/item/:id' do
  # this matches &quot;GET /item/10&quot; and &quot;GET /item/11&quot;
  # params[:id] is &quot;10&quot; or &quot;11&quot;
  &quot;You reached #{params[:id]}&quot;
end
</programlisting>
    <para>
      Sinatra also supports route matching via splats, wildcards and
      regular expressions. For more information on this I recommend
      reading the official
      <ulink url="http://www.sinatrarb.com/documentation">docs</ulink>.
      Let’s now take a look at handlers.
    </para>
    <para>
      Sinatra includes convenient handler methods for tasks such as
      redirection, halting and passing.
    </para>
    <sect3 id="redirection">
      <title>Redirection</title>
      <para>
        A simple route supporting redirection which returns a 302
        response can be written as follows:
      </para>
      <programlisting language="ruby">
get '/items' do
      redirect '/items/welcome'
end
</programlisting>
      <para>
        And if we wish to pass additional parameters such as arguments
        we can do so like this: redirect
        <quote>http://site.com/</quote>, <quote>Oops! I think we have a
        problem!</quote>
      </para>
    </sect3>
    <sect3 id="halting">
      <title>Halting</title>
      <para>
        To immediately stop a request (halting) we can use
        <quote>halt</quote>. Heres an example of halting a request where
        we specify the message body:
      </para>
      <para>
        <literal>halt &quot;who goes there!?&quot;</literal>
      </para>
    </sect3>
    <sect3 id="passing">
      <title>Passing</title>
      <para>
        <quote>Passing</quote> is the concept of deferring processing of
        a block to the next matching route. We do this using
        <literal>pass</literal>. In the following example if a parameter
        isnt the username we expect (rick-astley) we simply pass it on:
      </para>
      <programlisting language="ruby">
get '/members/:username' do
 pass unless params[:username] == 'rick-astley'
 'Never gonna give you up, never gonna let you down'
end

get '/member/*' do
 'Welcome!'
end
</programlisting>
      <para>
        There are also handler methods that can assist with sessions
        (specifically, cookie-based session handling). To use Sinatra’s
        session handling, first enable it in your application with:
      </para>
      <programlisting language="ruby">
enable :sessions
</programlisting>
      <para>
        You can then use the session handling capabilities as follows:
      </para>
      <programlisting language="ruby">
get '/items' do
  session['visitCounter'] ||= 0;
  session['visitCounter'] += 1;
  &quot;This page has been accessed #{session['visitCounter']} times&quot;
end
</programlisting>
      <para>
        Note: By default enable:sessions will store all data in cookies.
        If this is not desired, you can not call this and instead use
        some Rack middleware instead. For more on this see
        <ulink url="http://www.sinatrarb.com/intro#Using%20Sessions">here</ulink>.
      </para>
      <para>
        This only touches the surface of what can be done using routes
        and handlers, but is sufficient for us to write the
        Sinatra-powered API service we require in the practical section
        of this chapter.
      </para>
    </sect3>
  </sect2>
</sect1>
<sect1 id="templating-and-haml">
  <title>Templating And HAML</title>
  <para>
    Let’s now discuss templating.Out of the box, we can begin using
    templates in our Sinatra applications with ERB. ERB is included with
    Ruby and allows Ruby code to be added to any plain text document for
    the purpose of generating information or flow control. In the
    following example using an ERB template, note that views are by
    default located in the <literal>views</literal> directory of our
    application.
  </para>
  <programlisting language="ruby">
get '/items' do
  erb :default
  # renders views/default.erb
end
</programlisting>
  <para>
    A useful Sinatra convention worth noting is how layouts are handled.
    Layouts automatically search for a views/layout template which is
    rendered before any other views are loaded. With ERB, our
    views/layout.erb file could look as follows:
  </para>
  <programlisting language="html">
&lt;html&gt;
  &lt;head&gt;&lt;/head&gt;
  &lt;body&gt;
    &lt;%= data %&gt;
  &lt;/body&gt;
&lt;/html&gt;
</programlisting>
  <para>
    Haml is a popular alternative to ERB which offers an abstract syntax
    for writing application templates. It has been said to be:
  </para>
  <itemizedlist>
    <listitem>
      <para>
        Straight-forward to learn
      </para>
    </listitem>
    <listitem>
      <para>
        Very easy to read and use for visually expressing a hierarchy of
        DOM elements
      </para>
    </listitem>
    <listitem>
      <para>
        Popular with web designers as it builds on top of CSS syntax
      </para>
    </listitem>
    <listitem>
      <para>
        Well documented with a large community backing it
      </para>
    </listitem>
    <listitem>
      <para>
        Almost as fast as ERB
      </para>
    </listitem>
  </itemizedlist>
  <para>
    For the purpose of comparison, below we can see an ERB template
    compared to it’s Haml equivalent.
  </para>
  <sect2 id="erb">
    <title>ERB</title>
    <programlisting language="html">
&lt;div class=&quot;todo&quot; id=&quot;content&quot;&gt;
  &lt;h2 class=&quot;entry_title&quot;&gt;&lt;%= h @todo.title %&gt;&lt;/h2&gt;
  &lt;div class=&quot;entry_link&quot;&gt;&lt;%= link_to('link', @todo.link) %&gt;&lt;/div&gt;
&lt;/div&gt;
</programlisting>
  </sect2>
  <sect2 id="haml">
    <title>Haml</title>
    <programlisting language="html">
.todo#content
  %h2.entry_title= @todo.title
  .entry_link= link_to('link', @todo.link)
</programlisting>
    <para>
      One of the first things we notice is that the Haml snippet looks
      significantly more like CSS than it does traditional markup. It’s
      much easier to read and we no longer need to be concerned with
      divs, spans, closing tags or other semantic rules that usually
      mean more keystrokes. The approach taken to making whitespace a
      part of the syntax also means it can be much easier to compare
      changes between multiple documents (especially if you’re doing a
      diff).
    </para>
    <para>
      In the list of Haml features, we briefly mentioned web designers.
      As developers, we regularly need to communicate and work with
      designers, but we always have to remember that at the end of the
      day, they are not programmers. They’re usually more concerned with
      the look and the feel of an application, but if we want them to
      write mark-up as a part of the templates or skins they create,
      Haml is a simpler option that has worked well for teams at a
      number of companies.
    </para>
    <programlisting language="ruby">
%h1 This is some h1 text
%h2 This is some h2 text.

%p Now we have a line containing a single instance variable: @content
%p= @content

%p Embedding Ruby code in the middle of a line can be done using ==.
%p== Here is an example: #{@foobar}

%p We can also add attributes using {}
%p{:style =&gt; &quot;color:green&quot;} We just made this paragraph green!

%p You'll want to apply classes and ids to your DOM, too.
%p.foo This has the foo class
%p.bar This has the bar class
%p#foobar This has the foobar id
%p.foo#foobar Or you can combine them!

%p Nesting can be done like this
%p
  Or even like this
</programlisting>
    <para>
      Note: Haml is whitespace sensitive and will not correctly work if
      it isn’t indented by an even number of spaces. This is due to
      whitespace being used for nesting in place of the classic HTML
      markup approach of closing tags.
    </para>
  </sect2>
</sect1>
<sect1 id="mongodb-ruby-driver">
  <title>MongoDB Ruby Driver</title>
  <sect2 id="getting-started">
    <title>Getting started</title>
    <para>
      Once the MongoDB Ruby driver is installed, we can begin to use it
      to connect to a Mongo database. To create a connection using
      localhost, we simply specify the driver as a dependency. Assuming
      we’re using the default port we can then connect as follows:
    </para>
    <programlisting language="ruby">
require 'mongo'

# where 'learning-mongo' is the name of our database:
db = Connection.new.db('learning-mongo');
</programlisting>
    <para>
      We probably also want to place some data into
      <quote>learning-mongo</quote>. It could be as simple as a note, so
      why don’t we go ahead and begin a notes collection?:
    </para>
    <para>
      <literal>ruby notes = db.collection('notes')</literal> Something
      interesting worth noting is that at this point, we haven’t
      actually created the database nor the collection we’re referencing
      above.
    </para>
    <para>
      Neither of these items exist in Mongo (just yet) but as we’re
      working with a new database but they will once we insert some real
      data.
    </para>
    <para>
      A new note could be defined using key/value pairs as follows and
      then inserted into <quote>learning-mongo</quote> using
      <literal>collection.insert()</literal>:
    </para>
    <programlisting language="ruby">
our_note = { :text =&gt; 'Remember the milk', :remindInterval =&gt; 'weekly'}
note_id = notes.insert(our_note)
</programlisting>
    <para>
      What is returned from inserting a note into the notes collection
      is an <literal>ObjectId</literal> reference for the note from
      Mongo. This is useful as we can re-use it to locate the same
      document in our database.
    </para>
    <programlisting language="ruby">
note = notes.find( :id =&gt; note_id ).first
</programlisting>
    <para>
      This can also be used in conjunction with Mongo’s
      <literal>collection.update()</literal> method and
      <ulink url="http://www.mongodb.org/display/DOCS/Updating">query</ulink>
      operators (i.e <literal>$set</literal>) to replace fields in an
      existing document.
    </para>
    <para>
      We might update an entire document as follows:
    </para>
    <programlisting language="ruby">
note = notes.find( :id =&gt; note_id ).first
note[:text] = 'Remember the bread'
notes.update({ :_id =&gt; note_id }, note)
</programlisting>
    <para>
      or using <literal>$set</literal>, update an existing document
      without overwriting the entire object as like this:
    </para>
    <programlisting language="ruby">
notes.update({ :_id =&gt; note_id }, '$set' =&gt; { :text = &gt; 'Remember the bread' })
</programlisting>
    <para>
      Useful to know: Almost each MongoDB document has an _id field as
      it’s first attribute. This can normally be of any type, however a
      special BSON datatype is provided for object ids. It’s a 12-byte
      binary value that has a high probability of being unique when
      allocated.
    </para>
    <para>
      Note: Whilst we opted for the MongoDB Ruby Driver for this stack,
      you may also be interested in
      <emphasis role="strong">DataMapper</emphasis> - a solution which
      allows us to use the same API to talk to a number of different
      datastores. This works well for both relational and non-relational
      databases and more information is available on the official
      <ulink url="http://datamapper.org/why.html">project page</ulink>.
      <ulink url="http://sinatra-book.gittr.com/#datamapper">Sinatra:
      The Book</ulink> also contains a brief tutorial on DataMapper for
      anyone interested in exploring it further.
    </para>
  </sect2>
</sect1>
<sect1 id="practical-1">
  <title>Practical</title>
  <para>
    We’re going to use Sinatra in a similar manner to how we used
    Express in the last chapter. It will power a RESTful API supporting
    CRUD operations. Together with a MongoDB data store, this will allow
    us to easily persist data (todo items) whilst ensuring they are
    stored in a database. If you’ve read the previous chapter or have
    gone through any of the Todo examples covered so far, you will find
    this surprisingly straight-forward.
  </para>
  <para>
    Remember that the default Todo example included with Backbone.js
    already persists data, although it does this via a localStorage
    adapter. Luckily there aren’t a great deal of changes needed to
    switch over to using our Sinatra-based API. Let’s briefly review the
    code that will be powering the CRUD operations for this sections
    practical, as we go course won’t be starting off with a
    near-complete base for most of our real world applications.
  </para>
  <sect2 id="installing-the-prerequisites">
    <title><a id="preq">Installing The Prerequisites</a></title>
    <sect3 id="ruby">
      <title>Ruby</title>
      <para>
        If using OSX or Linux, Ruby may be one of a number of
        open-source packages that come pre-installed and you can skip
        over to the next paragraph. In case you would like to check if
        check if you have Ruby installed, open up the terminal prompt
        and type:
      </para>
      <para>
        <literal>$ ruby -v</literal>
      </para>
      <para>
        The output of this will either be the version of Ruby installed
        or an error complaining that Ruby wasn’t found.
      </para>
      <para>
        Should you need to install Ruby manually (e.g for an operating
        system such as Windows), you can do so by downloading the latest
        version from http://www.ruby-lang.org/en/downloads/.
        Alternatively, (RVM)[http://beginrescueend.com/rvm/install/]
        (Ruby Version Manager) is a command-line tool that allows you to
        easily install and manage multiple ruby environments with ease.
      </para>
    </sect3>
    <sect3 id="ruby-gems">
      <title>Ruby Gems</title>
      <para>
        Next, we will need to install Ruby Gems. Gems are a standard way
        to package programs or libraries written in Ruby and with Ruby
        Gems it’s possible to install additional dependencies for Ruby
        applications very easily.
      </para>
      <para>
        On OSX, Linux or Windows go to
        <ulink url="http://rubyforge.org/projects/rubygems">http://rubyforge.org/projects/rubygems</ulink>
        and download the latest version of Ruby Gems. Once downloaded,
        open up a terminal, navigate to the folder where this resides
        and enter:
      </para>
      <programlisting>
$&gt; tar xzvf rubygems.tgz
$&gt; cd rubygems
$&gt; sudo ruby setup.rb
</programlisting>
      <para>
        There will likely be a version number included in your download
        and you should make sure to include this when tying the above.
        Finally, a symlink (symbolic link) to tie everything togther
        should be fun as follows:
      </para>
      <para>
        <literal>$ sudo ln -s /usr/bin/gem1.8.17 /usr/bin/gem</literal>
      </para>
      <para>
        To check that Ruby Gems has been correctly installed, type the
        following into your terminal:
      </para>
      <programlisting>
$ gem -v
</programlisting>
    </sect3>
    <sect3 id="sinatra">
      <title>Sinatra</title>
      <para>
        With Ruby Gems setup, we can now easily install Sinatra. For
        Linux or OSX type this in your terminal:
      </para>
      <para>
        <literal>$ sudo gem install sinatra</literal>
      </para>
      <para>
        and if you’re on Windows, enter the following at a command
        prompt:
      </para>
      <para>
        <literal>c:\\ &gt; gem install sinatra</literal>
      </para>
    </sect3>
    <sect3 id="haml-1">
      <title>Haml</title>
      <para>
        As with other DSLs and frameworks, Sinatra supports a wide range
        of different templating engines.
        <ulink url="http://www.ruby-doc.org/stdlib/libdoc/erb/rdoc/classes/ERB.html">ERB</ulink>
        is the one most often recommended by the Sinatra camp, however
        as a part of this chapter, we’re going to explore the use of
        <ulink url="http://haml.hamptoncatlin.com/">Haml</ulink> to
        define our application templates.
      </para>
      <para>
        Haml stands for HTML Abstractional Markup Language and is a
        lightweight markup language abstraction that can be used to
        describe HTML without the need to use traditional markup
        language semantics (such as opening and closing tags).
      </para>
      <para>
        Installing Haml can be done in just a line using Ruby Gems as
        follows:
      </para>
      <para>
        <literal>$ gem install haml</literal>
      </para>
    </sect3>
    <sect3 id="mongodb-1">
      <title>MongoDB</title>
      <para>
        If you haven’t already downloaded and installed MongoDB from an
        earlier chapter, please
        <ulink url="http://www.mongodb.org/downloads">do so</ulink> now.
        With Ruby Gems, Mongo can be installed in just one line:
      </para>
      <para>
        <literal>$ gem install mongodb</literal>
      </para>
      <para>
        We now require two further steps to get everything up and
        running.
      </para>
      <sect4 id="data-directories">
        <title>1.Data directories</title>
        <para>
          MongoDB stores data in the bin/data/db folder but won’t
          actually create this directory for you. Navigate to where
          you’ve downloaded and extracted Mongo and run the following
          from terminal:
        </para>
        <programlisting>
sudo mkdir -p /data/db/
sudo chown `id -u` /data/db
</programlisting>
      </sect4>
      <sect4 id="running-and-connecting-to-your-server">
        <title>2.Running and connecting to your server</title>
        <para>
          Once this is done, open up two terminal windows.
        </para>
        <para>
          In the first, cd to your MongoDB bin directory or type in the
          complete path to it. You’ll need to start mongod.
        </para>
        <programlisting>
$ ./bin/mongod
</programlisting>
        <para>
          Finally, in the second terminal, start the mongo shell which
          will connect up to localhost by default.
        </para>
        <programlisting>
$ ./bin/mongo
</programlisting>
      </sect4>
    </sect3>
    <sect3 id="mongodb-ruby-driver-1">
      <title>MongoDB Ruby Driver</title>
      <para>
        As we’ll be using the
        <ulink url="https://github.com/mongodb/mongo-ruby-driver">MongoDB
        Ruby Driver</ulink>, we’ll also require the following gems:
      </para>
      <para>
        The gem for the driver itself:
      </para>
      <programlisting>
$ gem install mongo
</programlisting>
      <para>
        and the driver’s other prerequisite, bson:
      </para>
      <programlisting>
$ gem install bson_ext
</programlisting>
      <para>
        This is basically a collection of extensions used to increase
        serialization speed.
      </para>
      <para>
        That’s it for our prerequisites!.
      </para>
    </sect3>
  </sect2>
  <sect2 id="tutorial">
    <title>Tutorial</title>
    <para>
      To get started, let’s get a local copy of the practical
      application working on our system.
    </para>
    <sect3 id="application-files">
      <title>Application Files</title>
      <para>
        Clone
        <ulink url="http://github.com/addyosmani/backbone-fundamentals">this</ulink>
        repository and navigate to
        <literal>/practicals/stacks/option3</literal>. Now run the
        following lines at the terminal:
      </para>
      <programlisting>
ruby app.rb
</programlisting>
      <para>
        Finally, navigate to <code>http://localhost:4567/todo</code> to
        see the application running successfully.
      </para>
      <para>
        <emphasis role="strong">Note:</emphasis> The Haml layout files
        for Option 3 can be found in the /views folder.
      </para>
      <para>
        The directory structure for our practical application is as
        follows:
      </para>
      <programlisting>
--public
----css
----img
----js
-----script.js
----test
--views
app.rb
</programlisting>
      <para>
        The <literal>public</literal> directory contains the scripts and
        stylesheets for our application and uses HTML5 Boilerplate as a
        base. You can find the Models, Views and Collections for this
        section within <literal>public/js/scripts.js</literal> (however,
        this can of course be expanded into sub-directories for each
        component if desired).
      </para>
      <para>
        <literal>scripts.js</literal> contains the following Backbone
        component definitions:
      </para>
      <programlisting>
--Models
----Todo

--Collections
----TodoList

--Views
---TodoView
---AppView
</programlisting>
      <para>
        <literal>app.rb</literal> is the small Sinatra application that
        powers our backend API.
      </para>
      <para>
        Lastly, the <literal>views</literal> directory hosts the Haml
        source files for our application’s index and templates, both of
        which are compiled to standard HTML markup at runtime.
      </para>
      <para>
        These can be viewed along with other note-worthy snippets of
        code from the application below.
      </para>
    </sect3>
    <sect3 id="backbone">
      <title>Backbone</title>
      <sect4 id="views-2">
        <title>Views</title>
        <para>
          In our main application view (AppView), we want to load any
          previously stored Todo items in our Mongo database when the
          view initializes. This is done below with the line
          <literal>Todos.fetch()</literal> in the
          <literal>initialize()</literal> method where we also bind to
          the relevant events on the <literal>Todos</literal> collection
          for when items are added or changed.
        </para>
        <programlisting language="javascript">
// Our overall **AppView** is the top-level piece of UI.
var AppView = Backbone.View.extend({

    // Instead of generating a new element, bind to the existing skeleton of
    // the App already present in the HTML.
    el: $(&quot;#todoapp&quot;),

    // Our template for the line of statistics at the bottom of the app.
    statsTemplate: _.template($('#stats-template').html()),

    // Delegated events for creating new items, and clearing completed ones.
    events: {
      &quot;keypress #new-todo&quot;: &quot;createOnEnter&quot;,
      &quot;keyup #new-todo&quot;: &quot;showTooltip&quot;,
      &quot;click .todo-clear a&quot;: &quot;clearCompleted&quot;
    },

    // At initialization
    initialize: function() {
      this.input = this.$(&quot;#new-todo&quot;);

      Todos.on('add', this.addOne, this);
      Todos.on('reset', this.addAll, this);
      Todos.on('all', this.render, this);

      Todos.fetch();
    },

    // Re-rendering the App just means refreshing the statistics -- the rest
    // of the app doesn't change.
    render: function() {
      this.$('#todo-stats').html(this.statsTemplate({
        total: Todos.length,
        done:
 ….
</programlisting>
      </sect4>
    </sect3>
    <sect3 id="collections-1">
      <title>Collections</title>
      <para>
        In the TodoList collection below, we’ve set the
        <literal>url</literal> property to point to
        <literal>/api/todos</literal> to reference the collection’s
        location on the server. When we attempt to access this from our
        Sinatra-backed API, it should return a list of all the Todo
        items that have been previously stored in Mongo.
      </para>
      <para>
        For the sake of thoroughness, our API will also support
        returning the data for a specific Todo item via
        <literal>/api/todos/itemID</literal>. We’ll take a look at this
        again when writing the Ruby code powering our backend.
      </para>
      <programlisting language="javascript">
 // Todo Collection

  var TodoList = Backbone.Collection.extend({

    // Reference to this collection's model.
    model: Todo,

    // Save all of the todo items under the `&quot;todos&quot;` namespace.
    // localStorage: new Store(&quot;todos&quot;),
    url: '/api/todos',

    // Filter down the list of all todo items that are finished.
    done: function() {
      return this.filter(function(todo){ return todo.get('done'); });
    },

    // Filter down the list to only todo items that are still not finished.
    remaining: function() {
      return this.without.apply(this, this.done());
    },

    // We keep the Todos in sequential order, despite being saved by unordered
    // GUID in the database. This generates the next order number for new items.
    nextOrder: function() {
      if (!this.length) return 1;
      return this.last().get('order') + 1;
    },

    // Todos are sorted by their original insertion order.
    comparator: function(todo) {
      return todo.get('order');
    }

  });
</programlisting>
    </sect3>
    <sect3 id="model">
      <title>Model</title>
      <para>
        The model for our Todo application remains largely unchanged
        from the versions previously covered in this book. It is however
        worth noting that calling the function
        <literal>model.url()</literal> within the below would return the
        relative URL where a specific Todo item could be located on the
        server.
      </para>
      <programlisting language="javascript">

  // Our basic **Todo** model has `text`, `order`, and `done` attributes.
  var Todo = Backbone.Model.extend({
    idAttribute: &quot;_id&quot;,

    // Default attributes for a todo item.
    defaults: function() {
      return {
        done: false,
        order: Todos.nextOrder()
      };
    },

    // Toggle the `done` state of this todo item.
    toggle: function() {
      this.save({done: !this.get(&quot;done&quot;)});
    }
  });
</programlisting>
    </sect3>
    <sect3 id="rubysinatra">
      <title>Ruby/Sinatra</title>
      <para>
        Now that we’ve defined our main models, views and collections
        let’s get the CRUD operations required by our Backbone
        application supported in our Sinatra API.
      </para>
      <para>
        We want to make sure that for any operations changing underlying
        data (create, update, delete) that our Mongo data store
        correctly reflects these.
      </para>
    </sect3>
    <sect3 id="app.rb">
      <title>app.rb</title>
      <para>
        For <literal>app.rb</literal>, we first define the dependencies
        required by our application. These include Sinatra, Ruby Gems,
        the MongoDB Ruby driver and the JSON gem.
      </para>
      <programlisting language="ruby">
require 'rubygems'
require 'sinatra'
require 'mongo'
require 'json'
</programlisting>
      <para>
        Next, we create a new connection to Mongo, specifying any custom
        configuration desired. If running a multi-threaded application,
        setting the <quote>pool_size</quote> allows us to specify a
        maximum pool size and <quote>timeout</quote> a maximum timeout
        for waiting for old connections to be released to the pool.
      </para>
      <programlisting language="ruby">
DB = Mongo::Connection.new.db(&quot;mydb&quot;, :pool_size =&gt; 5, :timeout =&gt; 5)
</programlisting>
      <para>
        Finally we define the routes to be supported by our API. Note
        that in the first two blocks - one for our application root
        (<literal>/</literal>) and the other for our todo items route
        <literal>/todo</literal> - we’re using Haml for template
        rendering.
      </para>
      <programlisting language="ruby">
class TodoApp &lt; Sinatra::Base

    get '/' do
      haml :index, :attr_wrapper =&gt; '&quot;', :locals =&gt; {:title =&gt; 'hello'}
    end

    get '/todo' do
      haml :todo, :attr_wrapper =&gt; '&quot;', :locals =&gt; {:title =&gt; 'Our Sinatra Todo app'}
    end
</programlisting>
      <para>
        <literal>haml :index</literal> instructs Sinatra to use the
        <literal>views/index.haml</literal> for the application index,
        whilst `<literal>attr_wrapper</literal> is simply defining the
        values to be used for any local variables defined inside the
        template. This similarly applies Todo items with the template
        `views/todo.haml’.
      </para>
      <para>
        The rest of our routes make use of the <literal>params</literal>
        hash and a number of useful helper methods included with the
        MongoDB Ruby driver. For more details on these, please read the
        comments I’ve made inline below:
      </para>
      <programlisting language="ruby">
get '/api/:thing' do
  # query a collection :thing, convert the output to an array, map the _id
  # to a string representation of the object's _id and finally output to JSON
  DB.collection(params[:thing]).find.to_a.map{|t| from_bson_id(t)}.to_json
end

get '/api/:thing/:id' do
  # get the first document with the id :id in the collection :thing as a single document (rather
  # than a Cursor, the standard output) using find_one(). Our bson utilities assist with
  # ID conversion and the final output returned is also JSON
  from_bson_id(DB.collection(params[:thing]).find_one(to_bson_id(params[:id]))).to_json
end

post '/api/:thing' do
  # parse the post body of the content being posted, convert to a string, insert into
  # the collection #thing and return the ObjectId as a string for reference
  oid = DB.collection(params[:thing]).insert(JSON.parse(request.body.read.to_s))
  &quot;{\&quot;_id\&quot;: \&quot;#{oid.to_s}\&quot;}&quot;
end

delete '/api/:thing/:id' do
  # remove the item with id :id from the collection :thing, based on the bson
  # representation of the object id
  DB.collection(params[:thing]).remove('_id' =&gt; to_bson_id(params[:id]))
end

put '/api/:thing/:id' do
  # collection.update() when used with $set (as covered earlier) allows us to set single values
  # in this case, the put request body is converted to a string, rejecting keys with the name '_id' for security purposes
  DB.collection(params[:thing]).update({'_id' =&gt; to_bson_id(params[:id])}, {'$set' =&gt; JSON.parse(request.body.read.to_s).reject{|k,v| k == '_id'}})
end

# utilities for generating/converting MongoDB ObjectIds
def to_bson_id(id) BSON::ObjectId.from_string(id) end
def from_bson_id(obj) obj.merge({'_id' =&gt; obj['_id'].to_s}) end

end
</programlisting>
      <para>
        That’s it. The above is extremely lean for an entire API, but
        does allow us to read and write data to support the
        functionality required by our client-side application.
      </para>
      <para>
        For more on what MongoDB and the MongoDB Ruby driver are capable
        of, please do feel free to read their documentation for more
        information.
      </para>
      <para>
        If you’re a developer wishing to take this example further, why
        not try to add some additional capabilities to the service:
      </para>
      <itemizedlist>
        <listitem>
          <para>
            Validation: improved validation of data in the API. What
            more could be done to ensure data sanitization?
          </para>
        </listitem>
        <listitem>
          <para>
            Search: search or filter down Todo items based on a set of
            keywords or within a certain date range
          </para>
        </listitem>
        <listitem>
          <para>
            Pagination: only return the Nth number of Todo items or
            items from a start and end-point
          </para>
        </listitem>
      </itemizedlist>
    </sect3>
    <sect3 id="hamltemplates">
      <title>Haml/Templates</title>
      <para>
        Finally, we move on to the Haml files that define our
        application index (layout.haml) and the template for a specific
        Todo item (todo.haml). Both of these are largely
        self-explanatory, but it’s useful to see the differences between
        the Jade approach we reviewed in the last chapter vs. using Haml
        for this implementation.
      </para>
      <para>
        Note: In our Haml snippets below, the forward slash character is
        used to indicate a comment. When this character is placed at the
        beginning of a line, it wraps all of the text after it into a
        HTML comment. e.g
      </para>
      <para>
        <literal>/ These are templates</literal>
      </para>
      <para>
        compiles to:
      </para>
      <para>
        <literal>&lt;!-- These are templates --&gt;</literal>
      </para>
    </sect3>
    <sect3 id="index.haml">
      <title>index.haml</title>
      <programlisting language="html">
%head
  %meta{'charset' =&gt; 'utf-8'}/
  %title=title
  %meta{'name' =&gt; 'description', 'content' =&gt; ''}/
  %meta{'name' =&gt; 'author', 'content' =&gt; ''}/
  %meta{'name' =&gt; 'viewport', 'content' =&gt; 'width=device-width,initial-scale=1'}/

  / CSS concatenated and minified via ant build script
  %link{'rel' =&gt; 'stylesheet', 'href' =&gt; 'css/style.css'}/
  / end CSS

  %script{'src' =&gt; 'js/libs/modernizr.min.js'}
%body
  %div#container
    %header
    %div#main
      = yield
    %footer
  /! end of #container

  %script{'src' =&gt; 'http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js'}

  / scripts concatenated and minified via ant build script
  %script{'src' =&gt; 'js/mylibs/underscore.js'}
  %script{'src' =&gt; 'js/mylibs/backbone.js'}
  %script{'defer' =&gt; true, 'src' =&gt; 'js/plugins.js'}
  %script{'defer' =&gt; true, 'src' =&gt; 'js/script.js'}
  / end scripts
</programlisting>
    </sect3>
    <sect3 id="todo.haml">
      <title>todo.haml</title>
      <programlisting language="html">
%div#todoapp
  %div.title
    %h1
      Todos
      %div.content
        %div#create-todo
          %input#new-todo{&quot;placeholder&quot; =&gt; &quot;What needs to be done?&quot;, &quot;type&quot; =&gt; &quot;text&quot;}/
          %span.ui-tooltip-top{&quot;style&quot; =&gt; &quot;display:none;&quot;} Press Enter to save this task
        %div#todos
          %ul#todo-list
        %div#todo-stats

/ Templates

%script#item-template{&quot;type&quot; =&gt; &quot;text/template&quot;}
  &lt;div class=&quot;todo &lt;%= done ? 'done' : '' %&gt;&quot;&gt;
  %div.display
    &lt;input class=&quot;check&quot; type=&quot;checkbox&quot; &lt;%= done ? 'checked=&quot;checked&quot;' : '' %&gt; /&gt;
    %div.todo-text
    %span#todo-destroy
  %div.edit
    %input.todo-input{&quot;type&quot; =&gt; &quot;text&quot;, &quot;value&quot; =&gt;&quot;&quot;}/
  &lt;/div&gt;

%script#stats-template{&quot;type&quot; =&gt; &quot;text/template&quot;}
  &lt;% if (total) { %&gt;
  %span.todo-count
    %span.number &lt;%= remaining %&gt;
    %span.word &lt;%= remaining == 1 ? 'item' : 'items' %&gt;
    left.
  &lt;% } %&gt;
  &lt;% if (done) { %&gt;
  %span.todo-clear
    %a{&quot;href&quot; =&gt; &quot;#&quot;}
      Clear
      %span.number-done &lt;%= done %&gt;
      completed
      %span.word-done &lt;%= done == 1 ? 'item' : 'items' %&gt;
  &lt;% } %&gt;
</programlisting>
    </sect3>
  </sect2>
  <sect2 id="conclusions">
    <title>Conclusions</title>
    <para>
      In this chapter, we looked at creating a Backbone application
      backed by an API powered by Ruby, Sinatra, Haml, MongoDB and the
      MongoDB driver. I personally found developing APIs with Sinatra a
      relatively painless experience and one which I felt was on-par
      with the effort required for the Node/Express implementation of
      the same application.
    </para>
    <para>
      This section is by no means the most comprehensive guide on
      building complex apps using all of the items in this particular
      stack. I do however hope it was an introduction sufficient enough
      to help you decide on what stack to try out for your next project.
    </para>
  </sect2>
  <sect2 id="advanced">
    <title># <a name="advanced">Advanced</a></title>
    <para>
    </para>
  </sect2>
  <sect2 id="modular-javascript">
    <title><a name="modularjs">Modular JavaScript</a></title>
    <para>
      When we say an application is modular, we generally mean it’s
      composed of a set of highly decoupled, distinct pieces of
      functionality stored in modules. As you probably know, loose
      coupling facilitates easier maintainability of apps by removing
      dependencies where possible. When this is implemented efficiently,
      its quite easy to see how changes to one part of a system may
      affect another.
    </para>
    <para>
      Unlike some more traditional programming languages however, the
      current iteration of JavaScript (ECMA-262) doesn’t provide
      developers with the means to import such modules of code in a
      clean, organized manner. It’s one of the concerns with
      specifications that haven’t required great thought until more
      recent years where the need for more organized JavaScript
      applications became apparent.
    </para>
    <para>
      Instead, developers at present are left to fall back on variations
      of the module or object literal patterns. With many of these,
      module scripts are strung together in the DOM with namespaces
      being described by a single global object where it’s still
      possible to incur naming collisions in your architecture. There’s
      also no clean way to handle dependency management without some
      manual effort or third party tools.
    </para>
    <para>
      Whilst native solutions to these problems will be arriving in ES
      Harmony, the good news is that writing modular JavaScript has
      never been easier and you can start doing it today.
    </para>
    <para>
      In this next part of the book, we’re going to look at how to use
      AMD modules and RequireJS for cleanly wrapping units of code in
      your application into manageable modules.
    </para>
  </sect2>
  <sect2 id="organizing-modules-with-requirejs-and-amd">
    <title><a name="organizingmodules">Organizing modules with RequireJS
    and AMD</a></title>
    <para>
      In case you haven’t used it before,
      <ulink url="http://requirejs.org">RequireJS</ulink> is a popular
      script loader written by James Burke - a developer who has been
      quite instrumental in helping shape the AMD module format, which
      we’ll discuss more shortly. Some of RequireJS’s capabilities
      include helping to load multiple script files, helping define
      modules with or without dependencies and loading in non-script
      dependencies such as text files.
    </para>
    <para>
      So, why use RequireJS with Backbone? Although Backbone is
      excellent when it comes to providing a sanitary structure to your
      applications, there are a few key areas where some additional help
      could be used:
    </para>
    <orderedlist numeration="arabic">
      <listitem>
        <para>
          Backbone doesn’t endorse a particular approach to
          modular-development. Although this means it’s quite open-ended
          for developers to opt for classical patterns like the
          module-pattern or Object Literals for structuring their apps
          (which both work fine), it also means developers aren’t sure
          of what works best when other concerns come into play, such as
          dependency management.
        </para>
      </listitem>
    </orderedlist>
    <para>
      RequireJS is compatible with the AMD (Asynchronous Module
      Definition) format, a format which was born from a desire to write
      something better than the <quote>write lots of script tags with
      implicit dependencies and manage them manually</quote> approach to
      development. In addition to allowing you to clearly declare
      dependencies, AMD works well in the browser, supports string IDs
      for dependencies, declaring multiple modules in the same file and
      gives you easy-to-use tools to avoid polluting the global
      namespace.
    </para>
    <orderedlist numeration="arabic">
      <listitem override="2">
        <para>
          Let’s discuss dependency management a little more as it can
          actually be quite challenging to get right if you’re doing it
          by hand. When we write modules in JavaScript, we ideally want
          to be able to handle the reuse of code units intelligently and
          sometimes this will mean pulling in other modules at run-time
          whilst at other times you may want to do this dynamically to
          avoid a large pay-load when the user first hits your
          application.
        </para>
      </listitem>
    </orderedlist>
    <para>
      Think about the GMail web-client for a moment. When users
      initially load up the page on their first visit, Google can simply
      hide widgets such as the chat module until a user has indicated
      (by clicking <quote>expand</quote>) that they wish to use it.
      Through dynamic dependency loading, Google could load up the chat
      module only then, rather than forcing all users to load it when
      the page first initializes. This can improve performance and load
      times and can definitely prove useful when building larger
      applications.
    </para>
    <para>
      I’ve previously written
      <ulink url="http://addyosmani.com/writing-modular-js">a detailed
      article</ulink> covering both AMD and other module formats and
      script loaders in case you’d like to explore this topic further.
      The takeaway is that although it’s perfectly fine to develop
      applications without a script loader or clean module format in
      place, it can be of significant benefit to consider using these
      tools in your application development.
    </para>
    <sect3 id="writing-amd-modules-with-requirejs">
      <title>Writing AMD modules with RequireJS</title>
      <para>
        As discussed above, the overall goal for the AMD format is to
        provide a solution for modular JavaScript that developers can
        use today. The two key concepts you need to be aware of when
        using it with a script-loader are a <literal>define()</literal>
        method for facilitating module definition and a
        <literal>require()</literal> method for handling dependency
        loading. <literal>define()</literal> is used to define named or
        unnamed modules based on the proposal using the following
        signature:
      </para>
      <programlisting language="javascript">
define(
    module_id /*optional*/,
    [dependencies] /*optional*/,
    definition function /*function for instantiating the module or object*/
);
</programlisting>
      <para>
        As you can tell by the inline comments, the
        <literal>module_id</literal> is an optional argument which is
        typically only required when non-AMD concatenation tools are
        being used (there may be some other edge cases where it’s useful
        too). When this argument is left out, we call the module
        <quote>anonymous</quote>. When working with anonymous modules,
        the idea of a module’s identity is DRY, making it trivial to
        avoid duplication of filenames and code.
      </para>
      <para>
        Back to the define signature, the dependencies argument
        represents an array of dependencies which are required by the
        module you are defining and the third argument
        (<quote>definition function</quote>) is a function that’s
        executed to instantiate your module. A barebone module
        (compatible with RequireJS) could be defined using
        <literal>define()</literal> as follows:
      </para>
      <programlisting language="javascript">
// A module ID has been omitted here to make the module anonymous

define(['foo', 'bar'],
    // module definition function
    // dependencies (foo and bar) are mapped to function parameters
    function ( foo, bar ) {
        // return a value that defines the module export
        // (i.e the functionality we want to expose for consumption)

        // create your module here
        var myModule = {
            doStuff:function(){
                console.log('Yay! Stuff');
            }
        }

        return myModule;
});
</programlisting>
      <sect4 id="alternate-syntax">
        <title>Alternate syntax</title>
        <para>
          There is also a
          <ulink url="http://requirejs.org/docs/whyamd.html#sugar">sugared
          version</ulink> of <literal>define()</literal> available that
          allows you to declare your dependencies as local variables
          using <literal>require()</literal>. This will feel familiar to
          anyone who’s used node, and can be easier to add or remove
          dependencies. Here is the previous snippet using the alternate
          syntax:
        </para>
        <programlisting language="javascript">
// A module ID has been omitted here to make the module anonymous

define(function(require){
        // module definition function
    // dependencies (foo and bar) are defined as local vars
    var foo = require('foo'),
        bar = require('bar');

        // return a value that defines the module export
        // (i.e the functionality we want to expose for consumption)

        // create your module here
        var myModule = {
            doStuff:function(){
                console.log('Yay! Stuff');
            }
        }

        return myModule;
});
</programlisting>
        <para>
          The <literal>require()</literal> method is typically used to
          load code in a top-level JavaScript file or within a module
          should you wish to dynamically fetch dependencies. An example
          of its usage is:
        </para>
        <programlisting language="javascript">
// Consider 'foo' and 'bar' are two external modules
// In this example, the 'exports' from the two modules loaded are passed as
// function arguments to the callback (foo and bar)
// so that they can similarly be accessed

require(['foo', 'bar'], function ( foo, bar ) {
        // rest of your code here
        foo.doSomething();
});
</programlisting>
        <para>
          <emphasis role="strong">Wrapping modules, views and other
          components with AMD</emphasis>
        </para>
        <para>
          Now that we’ve taken a look at how to define AMD modules,
          let’s review how to go about wrapping components like views
          and collections so that they can also be easily loaded as
          dependencies for any parts of your application that require
          them. At it’s simplest, a Backbone model may just require
          Backbone and Underscore.js. These are considered it’s
          dependencies and so, to write an AMD model module, we would
          simply do this:
        </para>
        <programlisting language="javascript">
define(['underscore', 'backbone'], function(_, Backbone) {
  var myModel = Backbone.Model.extend({

    // Default attributes
    defaults: {
      content: &quot;hello world&quot;,
    },

    // A dummy initialization method
    initialize: function() {
    },

    clear: function() {
      this.destroy();
      this.view.remove();
    }

  });
  return myModel;
});
</programlisting>
        <para>
          Note how we alias Underscore.js’s instance to
          <literal>_</literal> and Backbone to just
          <literal>Backbone</literal>, making it very trivial to convert
          non-AMD code over to using this module format. For a view
          which might require other dependencies such as jQuery, this
          can similarly be done as follows:
        </para>
        <programlisting language="javascript">
define([
  'jquery',
  'underscore',
  'backbone',
  'collections/mycollection',
  'views/myview'
  ], function($, _, Backbone, myCollection, myView){

  var AppView = Backbone.View.extend({
  ...
</programlisting>
        <para>
          Aliasing to the dollar-sign (<literal>$</literal>), once again
          makes it very easy to encapsulate any part of an application
          you wish using AMD.
        </para>
      </sect4>
    </sect3>
  </sect2>
  <sect2 id="keeping-your-templates-external-using-requirejs-and-the-text-plugin">
    <title><a name="externaltemplates">Keeping Your Templates External
    Using RequireJS And The Text Plugin</a></title>
    <para>
      Moving your [Underscore/Mustache/Handlebars] templates to external
      files is actually quite straight-forward. As this application
      makes use of RequireJS, I’ll discuss how to implement external
      templates using this specific script loader.
    </para>
    <para>
      RequireJS has a special plugin called text.js which is used to
      load in text file dependencies. To use the text plugin, simply
      follow these simple steps:
    </para>
    <orderedlist numeration="arabic">
      <listitem>
        <para>
          Download the plugin from
          http://requirejs.org/docs/download.html#text and place it in
          either the same directory as your application’s main JS file
          or a suitable sub-directory.
        </para>
      </listitem>
      <listitem>
        <para>
          Next, include the text.js plugin in your initial RequireJS
          configuration options. In the code snippet below, we assume
          that RequireJS is being included in our page prior to this
          code snippet being executed. Any of the other scripts being
          loaded are just there for the sake of example.
        </para>
      </listitem>
    </orderedlist>
    <programlisting language="javascript">
require.config( {
    paths: {
        'backbone': 'libs/AMDbackbone-0.5.3',
        'underscore': 'libs/underscore-1.2.2',
        'text': 'libs/require/text',
        'jquery': 'libs/jQuery-1.7.1',
        'json2': 'libs/json2',
        'datepicker': 'libs/jQuery.ui.datepicker',
        'datepickermobile': 'libs/jquery.ui.datepicker.mobile',
        'jquerymobile': 'libs/jquery.mobile-1.0'
    },
    baseUrl: 'app'
} );
</programlisting>
    <orderedlist numeration="arabic">
      <listitem override="3">
        <para>
          When the <literal>text!</literal> prefix is used for a
          dependency, RequireJS will automatically load the text plugin
          and treat the dependency as a text resource. A typical example
          of this in action may look like..
        </para>
      </listitem>
    </orderedlist>
    <programlisting language="javascript">
require(['js/app', 'text!templates/mainView.html'],
    function(app, mainView){
        // the contents of the mainView file will be
        // loaded into mainView for usage.
    }
);
</programlisting>
    <orderedlist numeration="arabic">
      <listitem override="4">
        <para>
          Finally we can use the text resource that’s been loaded for
          templating purposes. You’re probably used to storing your HTML
          templates inline using a script with a specific identifier.
        </para>
      </listitem>
    </orderedlist>
    <para>
      With Underscore.js’s micro-templating (and jQuery) this would
      typically be:
    </para>
    <para>
      HTML:
    </para>
    <programlisting>
&lt;script type=&quot;text/template&quot; id=&quot;mainViewTemplate&quot;&gt;
    &lt;% _.each( person, function( person_item ){ %&gt;
        &lt;li&gt;&lt;%= person_item.get(&quot;name&quot;) %&gt;&lt;/li&gt;
    &lt;% }); %&gt;
&lt;/script&gt;
</programlisting>
    <para>
      JS:
    </para>
    <programlisting language="javascript">
var compiled_template = _.template( $('#mainViewTemplate').html() );
</programlisting>
    <para>
      With RequireJS and the text plugin however, it’s as simple as
      saving your template into an external text file (say,
      <literal>mainView.html</literal>) and doing the following:
    </para>
    <programlisting language="javascript">
require(['js/app', 'text!templates/mainView.html'],
    function(app, mainView){

        var compiled_template = _.template( mainView );
    }
);
</programlisting>
    <para>
      That’s it!. You can then go applying your template to a view in
      Backbone doing something like:
    </para>
    <programlisting language="javascript">
collection.someview.el.html( compiled_template( { results: collection.models } ) );
</programlisting>
    <para>
      All templating solutions will have their own custom methods for
      handling template compilation, but if you understand the above,
      substituting Underscore’s micro-templating for any other solution
      should be fairly trivial.
    </para>
    <para>
      <emphasis role="strong">Note:</emphasis> You may also be
      interested in looking at
      <ulink url="https://github.com/ZeeAgency/requirejs-tpl">Require.js
      tpl</ulink>. It’s an AMD-compatible version of the Underscore
      templating system that also includes support for optimization
      (pre-compiled templates) which can lead to better performance and
      no evals. I have yet to use it myself, but it comes as a
      recommended resource.
    </para>
  </sect2>
  <sect2 id="optimizing-backbone-apps-for-production-with-the-requirejs-optimizer">
    <title><a name="optimizingrequirejs">Optimizing Backbone apps for
    production with the RequireJS Optimizer</a></title>
    <para>
      As experienced developers may know, an essential final step when
      writing both small and large JavaScript web applications is the
      build process. The majority of non-trivial apps are likely to
      consist of more than one or two scripts and so optimizing,
      minimizing and concatenating your scripts prior to pushing them to
      production will require your users to download a reduced number
      (if not just one) script file.
    </para>
    <para>
      Note: If you haven’t looked at build processes before and this is
      your first time hearing about them, you might find
      <ulink url="http://addyosmani.com/blog/client-side-build-process/">my
      post and screencast on this topic</ulink> useful.
    </para>
    <para>
      With some other structural JavaScript frameworks, my
      recommendation would normally be to implicitly use YUI Compressor
      or Google’s closure compiler tools, but we have a slightly more
      elegant method available, when it comes to Backbone if you’re
      using RequireJS. RequireJS has a command line optimization tool
      called r.js which has a number of capabilities, including:
    </para>
    <itemizedlist>
      <listitem>
        <para>
          Concatenating specific scripts and minifying them using
          external tools such as UglifyJS (which is used by default) or
          Google’s Closure Compiler for optimal browser delivery, whilst
          preserving the ability to dynamically load modules
        </para>
      </listitem>
      <listitem>
        <para>
          Optimizing CSS and stylesheets by inlining CSS files imported
          using @import, stripping out comments etc.
        </para>
      </listitem>
      <listitem>
        <para>
          The ability to run AMD projects in both Node and Rhino (more
          on this later)
        </para>
      </listitem>
    </itemizedlist>
    <para>
      You’ll notice that I mentioned the word <quote>specific</quote> in
      the first bullet point. The RequireJS optimizer only concatenates
      module scripts that have been specified in arrays of string
      literals passed to top-level (i.e non-local) require and define
      calls. As clarified by the
      <ulink url="http://requirejs.org/docs/optimization.html">optimizer
      docs</ulink> this means that Backbone modules defined like this:
    </para>
    <programlisting language="javascript">
define(['jquery','backbone','underscore', 'collections/sample','views/test'],
    function($,Backbone, _, Sample, Test){
        //...
    });
</programlisting>
    <para>
      will combine fine, however inline dependencies such as:
    </para>
    <programlisting language="javascript">
var models = someCondition ? ['models/ab','models/ac'] : ['models/ba','models/bc'];
</programlisting>
    <para>
      will be ignored. This is by design as it ensures that dynamic
      dependency/module loading can still take place even after
      optimization.
    </para>
    <para>
      Although the RequireJS optimizer works fine in both Node and Java
      environments, it’s strongly recommended to run it under Node as it
      executes significantly faster there. In my experience, it’s a
      piece of cake to get setup with either environment, so go for
      whichever you feel most comfortable with.
    </para>
    <para>
      To get started with r.js, grab it from the
      <ulink url="http://requirejs.org/docs/download.html#rjs">RequireJS
      download page</ulink> or
      <ulink url="http://requirejs.org/docs/optimization.html#download">through
      NPM</ulink>. Now, the RequireJS optimizer works absolutely fine
      for single script and CSS files, but for most cases you’ll want to
      actually optimize an entire Backbone project. You
      <emphasis>could</emphasis> do this completely from the
      command-line, but a cleaner option is using build profiles.
    </para>
    <para>
      Below is an example of a build file taken from the modular jQuery
      Mobile app referenced later in this book. A
      <emphasis role="strong">build profile</emphasis> (commonly named
      <literal>app.build.js</literal>) informs RequireJS to copy all of
      the content of <literal>appDir</literal> to a directory defined by
      <literal>dir</literal> (in this case
      <literal>../release</literal>). This will apply all of the
      necessary optimizations inside the release folder. The
      <literal>baseUrl</literal> is used to resolve the paths for your
      modules. It should ideally be relative to
      <literal>appDir</literal>.
    </para>
    <para>
      Near the bottom of this sample file, you’ll see an array called
      <literal>modules</literal>. This is where you specify the module
      names you wish to have optimized. In this case we’re optimizing
      the main application called <quote>app</quote>, which maps to
      <literal>appDir/app.js</literal>. If we had set the
      <literal>baseUrl</literal> to <quote>scripts</quote>, it would be
      mapped to <literal>appDir/scripts/app.js</literal>.
    </para>
    <programlisting language="javascript">
({
    appDir: &quot;./&quot;,
    baseUrl: &quot;./&quot;,
    dir: &quot;../release&quot;,
    paths: {
       'backbone': 'libs/AMDbackbone-0.5.3',
        'underscore': 'libs/underscore-1.2.2',
        'jquery': 'libs/jQuery-1.7.1',
        'json2': 'libs/json2',
        'datepicker': 'libs/jQuery.ui.datepicker',
        'datepickermobile': 'libs/jquery.ui.datepicker.mobile',
        'jquerymobile': 'libs/jquery.mobile-1.0'
    },
    optimize: &quot;uglify&quot;,
    modules: [
        {
            name: &quot;app&quot;,
            exclude: [
                // If you prefer not to include certain libs exclude them here
            ]
        }
    ]
})
</programlisting>
    <para>
      The way the build system in r.js works is that it traverses app.js
      (whatever modules you’ve passed) and resolved dependencies,
      concatenating them into the final <literal>release</literal>(dir)
      folder. CSS is treated the same way.
    </para>
    <para>
      The build profile is usually placed inside the
      <quote>scripts</quote> or <quote>js</quote> directory of your
      project. As per the docs, this file can however exist anywhere you
      wish, but you’ll need to edit the contents of your build profile
      accordingly.
    </para>
    <para>
      Finally, to run the build, execute the following command once
      inside your <literal>appDir</literal> or
      <literal>appDir/scripts</literal> directory:
    </para>
    <programlisting language="javascript">
node ../../r.js -o app.build.js
</programlisting>
    <para>
      That’s it. As long as you have UglifyJS/Closure tools setup
      correctly, r.js should be able to easily optimize your entire
      Backbone project in just a few key-strokes. If you would like to
      learn more about build profiles, James Burke has a
      <ulink url="https://github.com/jrburke/r.js/blob/master/build/example.build.js">heavily
      commented sample file</ulink> with all the possible options
      available.
    </para>
  </sect2>
  <sect2 id="practical-building-a-modular-backbone-app-with-amd-requirejs">
    <title><a name="practicalrequirejs">Practical: Building a modular
    Backbone app with AMD &amp; RequireJS</a></title>
    <para>
      In this chapter, we’ll look at our first practical Backbone &amp;
      RequireJS project - how to build a modular Todo application. The
      application will allow us to add new todos, edit new todos and
      clear todo items that have been marked as completed. For a more
      advanced practical, see the section on mobile Backbone
      development.
    </para>
    <para>
      The complete code for the application can can be found in the
      <literal>practicals/modular-todo-app</literal> folder of this repo
      (thanks to Thomas Davis and Jérôme Gravel-Niquet). Alternatively
      grab a copy of my side-project
      <ulink url="https://github.com/addyosmani/todomvc">TodoMVC</ulink>
      which contains the sources to both AMD and non-AMD versions.
    </para>
    <para>
      <emphasis role="strong">Note:</emphasis> Thomas may be covering a
      practical on this exercise in more detail on
      <ulink url="http://backbonetutorials.com">backbonetutorials.com</ulink>
      at some point soon, but for this section I’ll be covering what I
      consider the core concepts.
    </para>
    <sect3 id="overview">
      <title>Overview</title>
      <para>
        Writing a <quote>modular</quote> Backbone application can be a
        straight-forward process. There are however, some key conceptual
        differences to be aware of if opting to use AMD as your module
        format of choice:
      </para>
      <itemizedlist>
        <listitem>
          <para>
            As AMD isn’t a standard native to JavaScript or the browser,
            it’s necessary to use a script loader (such as RequireJS or
            curl.js) in order to support defining components and modules
            using this module format. As we’ve already reviewed, there
            are a number of advantages to using the AMD as well as
            RequireJS to assist here.
          </para>
        </listitem>
        <listitem>
          <para>
            Models, views, controllers and routers need to be
            encapsulated <emphasis>using</emphasis> the AMD-format. This
            allows each component of our Backbone application to cleanly
            manage dependencies (e.g collections required by a view) in
            the same way that AMD allows non-Backbone modules to.
          </para>
        </listitem>
        <listitem>
          <para>
            Non-Backbone components/modules (such as utilities or
            application helpers) can also be encapsulated using AMD. I
            encourage you to try developing these modules in such a way
            that they can both be used and tested independent of your
            Backbone code as this will increase their ability to be
            re-used elsewhere.
          </para>
        </listitem>
      </itemizedlist>
      <para>
        Now that we’ve reviewed the basics, let’s take a look at
        developing our application. For reference, the structure of our
        app is as follows:
      </para>
      <programlisting>
index.html
...js/
    main.js
    .../models
            todo.js
    .../views
            app.js
            todos.js
    .../collections
            todos.js
    .../templates
            stats.html
            todos.html
    ../libs
        .../backbone
        .../jquery
        .../underscore
        .../require
                require.js
                text.js
...css/
</programlisting>
    </sect3>
    <sect3 id="markup">
      <title>Markup</title>
      <para>
        The markup for the application is relatively simple and consists
        of three primary parts: an input section for entering new todo
        items (<literal>create-todo</literal>), a list section to
        display existing items (which can also be edited in-place)
        (<literal>todo-list</literal>) and finally a section summarizing
        how many items are left to be completed
        (<literal>todo-stats</literal>).
      </para>
      <programlisting>
&lt;div id=&quot;todoapp&quot;&gt;

      &lt;div class=&quot;content&quot;&gt;

        &lt;div id=&quot;create-todo&quot;&gt;
          &lt;input id=&quot;new-todo&quot; placeholder=&quot;What needs to be done?&quot; type=&quot;text&quot; /&gt;
          &lt;span class=&quot;ui-tooltip-top&quot;&gt;Press Enter to save this task&lt;/span&gt;
        &lt;/div&gt;

        &lt;div id=&quot;todos&quot;&gt;
          &lt;ul id=&quot;todo-list&quot;&gt;&lt;/ul&gt;
        &lt;/div&gt;

        &lt;div id=&quot;todo-stats&quot;&gt;&lt;/div&gt;

      &lt;/div&gt;

&lt;/div&gt;
</programlisting>
      <para>
        The rest of the tutorial will now focus on the JavaScript side
        of the practical.
      </para>
    </sect3>
    <sect3 id="configuration-options">
      <title>Configuration options</title>
      <para>
        If you’ve read the earlier chapter on AMD, you may have noticed
        that explicitly needing to define each dependency a Backbone
        module (view, collection or other module) may require with it
        can get a little tedious. This can however be improved.
      </para>
      <para>
        In order to simplify referencing common paths the modules in our
        application may use, we use a RequireJS
        <ulink url="http://requirejs.org/docs/api.html#config">configuration
        object</ulink>, which is typically defined as a top-level script
        file. Configuration objects have a number of useful
        capabilities, the most useful being mode name-mapping. Name-maps
        are basically a key:value pair, where the key defines the alias
        you wish to use for a path and the value represents the true
        location of the path.
      </para>
      <para>
        In the code-sample below, you can see some typical examples of
        common name-maps which include: <literal>backbone</literal>,
        <literal>underscore</literal>, <literal>jquery</literal> and
        depending on your choice, the RequireJS <literal>text</literal>
        plugin, which assists with loading text assets like templates.
      </para>
      <para>
        <emphasis role="strong">main.js</emphasis>
      </para>
      <programlisting language="javascript">
require.config({
  baseUrl:'../',
  paths: {
    jquery: 'libs/jquery/jquery-min',
    underscore: 'libs/underscore/underscore-min',
    backbone: 'libs/backbone/backbone-optamd3-min',
    text: 'libs/require/text'
  }
});

require(['views/app'], function(AppView){
  var app_view = new AppView;
});
</programlisting>
      <para>
        The <literal>require()</literal> at the end of our main.js file
        is simply there so we can load and instantiation the primary
        view for our application (<literal>views/app.js</literal>).
        You’ll commonly see both this and the configuration object
        included the most top-level script file for a project.
      </para>
      <para>
        In addition to offering name-mapping, the configuration object
        can be used to define additional properties such as
        <literal>waitSeconds</literal> - the number of seconds to wait
        before script loading times out and <literal>locale</literal>,
        should you wish to load up i18n bundles for custom languages.
        The <literal>baseUrl</literal> is simply the path to use for
        module lookups.
      </para>
      <para>
        For more information on configuration objects, please feel free
        to check out the excellent guide to them in the
        <ulink url="http://requirejs.org/docs/api.html#config">RequireJS
        docs</ulink>.
      </para>
    </sect3>
    <sect3 id="modularizing-our-models-views-and-collections">
      <title>Modularizing our models, views and collections</title>
      <para>
        Before we dive into AMD-wrapped versions of our Backbone
        components, let’s review a sample of a non-AMD view. The
        following view listens for changes to its model (a Todo item)
        and re-renders if a user edits the value of the item.
      </para>
      <programlisting language="javascript">
var TodoView = Backbone.View.extend({

    //... is a list tag.
    tagName: &quot;li&quot;,

    // Cache the template function for a single item.
    template: _.template($('#item-template').html()),

    // The DOM events specific to an item.
    events: {
      &quot;click .check&quot; : &quot;toggleDone&quot;,
      &quot;dblclick div.todo-content&quot; : &quot;edit&quot;,
      &quot;click span.todo-destroy&quot; : &quot;clear&quot;,
      &quot;keypress .todo-input&quot; : &quot;updateOnEnter&quot;
    },

    // The TodoView listens for changes to its model, re-rendering. Since there's
    // a one-to-one correspondence between a **Todo** and a **TodoView** in this
    // app, we set a direct reference on the model for convenience.
    initialize: function() {
      this.model.bind('change', this.render, this);
      this.model.view = this;
    },
    ...
</programlisting>
      <para>
        Note how for templating the common practice of referencing a
        script by an ID (or other selector) and obtaining its value is
        used. This of course requires that the template being accessed
        is implicitly defined in our markup. The following is the
        <quote>embedded</quote> version of our template being referenced
        above:
      </para>
      <programlisting>
&lt;script type=&quot;text/template&quot; id=&quot;item-template&quot;&gt;
      &lt;div class=&quot;todo &lt;%= done ? 'done' : '' %&gt;&quot;&gt;
        &lt;div class=&quot;display&quot;&gt;
          &lt;input class=&quot;check&quot; type=&quot;checkbox&quot; &lt;%= done ? 'checked=&quot;checked&quot;' : '' %&gt; /&gt;
          &lt;div class=&quot;todo-content&quot;&gt;&lt;/div&gt;
          &lt;span class=&quot;todo-destroy&quot;&gt;&lt;/span&gt;
        &lt;/div&gt;
        &lt;div class=&quot;edit&quot;&gt;
          &lt;input class=&quot;todo-input&quot; type=&quot;text&quot; value=&quot;&quot; /&gt;
        &lt;/div&gt;
      &lt;/div&gt;
&lt;/script&gt;
</programlisting>
      <para>
        Whilst there is nothing wrong with the template itself, once we
        begin to develop larger applications requiring multiple
        templates, including them all in our markup on page-load can
        quickly become both unmanageable and come with performance
        costs. We’ll look at solving this problem in a minute.
      </para>
      <para>
        Let’s now take a look at the AMD-version of our view. As
        discussed earlier, the <quote>module</quote> is wrapped using
        AMD’s <literal>define()</literal> which allows us to specify the
        dependencies our view requires. Using the mapped paths to
        <quote>jquery</quote> etc. simplifies referencing common
        dependencies and instances of dependencies are themselves mapped
        to local variables that we can access (e.g <quote>jquery</quote>
        is mapped to <literal>$</literal>).
      </para>
      <para>
        <emphasis role="strong">views/todos.js</emphasis>
      </para>
      <programlisting language="javascript">
define([
  'jquery',
  'underscore',
  'backbone',
  'text!templates/todos.html'
  ], function($, _, Backbone, todosTemplate){
  var TodoView = Backbone.View.extend({

    //... is a list tag.
    tagName: &quot;li&quot;,

    // Cache the template function for a single item.
    template: _.template(todosTemplate),

    // The DOM events specific to an item.
    events: {
      &quot;click .check&quot; : &quot;toggleDone&quot;,
      &quot;dblclick div.todo-content&quot; : &quot;edit&quot;,
      &quot;click span.todo-destroy&quot; : &quot;clear&quot;,
      &quot;keypress .todo-input&quot; : &quot;updateOnEnter&quot;
    },

    // The TodoView listens for changes to its model, re-rendering. Since there's
    // a one-to-one correspondence between a **Todo** and a **TodoView** in this
    // app, we set a direct reference on the model for convenience.
    initialize: function() {
      this.model.bind('change', this.render, this);
      this.model.view = this;
    },

    // Re-render the contents of the todo item.
    render: function() {
      $(this.el).html(this.template(this.model.toJSON()));
      this.setContent();
      return this;
    },

    // Use `jQuery.text` to set the contents of the todo item.
    setContent: function() {
      var content = this.model.get('content');
      this.$('.todo-content').text(content);
      this.input = this.$('.todo-input');
      this.input.bind('blur', this.close);
      this.input.val(content);
    },
    ...
</programlisting>
      <para>
        From a maintenance perspective, there’s nothing logically
        different in this version of our view, except for how we
        approach templating.
      </para>
      <para>
        Using the RequireJS text plugin (the dependency marked
        <literal>text</literal>), we can actually store all of the
        contents for the template we looked at earlier in an external
        file (todos.html).
      </para>
      <para>
        <emphasis role="strong">templates/todos.html</emphasis>
      </para>
      <programlisting language="html">
&lt;div class=&quot;todo &lt;%= done ? 'done' : '' %&gt;&quot;&gt;
    &lt;div class=&quot;display&quot;&gt;
      &lt;input class=&quot;check&quot; type=&quot;checkbox&quot; &lt;%= done ? 'checked=&quot;checked&quot;' : '' %&gt; /&gt;
      &lt;div class=&quot;todo-content&quot;&gt;&lt;/div&gt;
      &lt;span class=&quot;todo-destroy&quot;&gt;&lt;/span&gt;
    &lt;/div&gt;
    &lt;div class=&quot;edit&quot;&gt;
      &lt;input class=&quot;todo-input&quot; type=&quot;text&quot; value=&quot;&quot; /&gt;
    &lt;/div&gt;
&lt;/div&gt;
</programlisting>
      <para>
        There’s no longer a need to be concerned with IDs for the
        template as we can map it’s contents to a local variable (in
        this case <literal>todosTemplate</literal>). We then simply pass
        this to the Underscore.js templating function
        <literal>_.template()</literal> the same way we normally would
        have the value of our template script.
      </para>
      <para>
        Next, let’s look at how to define models as dependencies which
        can be pulled into collections. Here’s an AMD-compatible model
        module, which has two default values: a
        <literal>content</literal> attribute for the content of a Todo
        item and a boolean <literal>done</literal> state, allowing us to
        trigger whether the item has been completed or not.
      </para>
      <para>
        <emphasis role="strong">models/todo.js</emphasis>
      </para>
      <programlisting language="javascript">
define(['underscore', 'backbone'], function(_, Backbone) {
  var TodoModel = Backbone.Model.extend({

    // Default attributes for the todo.
    defaults: {
      // Ensure that each todo created has `content`.
      content: &quot;empty todo...&quot;,
      done: false
    },

    initialize: function() {
    },

    // Toggle the `done` state of this todo item.
    toggle: function() {
      this.save({done: !this.get(&quot;done&quot;)});
    },

    // Remove this Todo from *localStorage* and delete its view.
    clear: function() {
      this.destroy();
      this.view.remove();
    }

  });
  return TodoModel;
});
</programlisting>
      <para>
        As per other types of dependencies, we can easily map our model
        module to a local variable (in this case
        <literal>Todo</literal>) so it can be referenced as the model to
        use for our <literal>TodosCollection</literal>. This collection
        also supports a simple <literal>done()</literal> filter for
        narrowing down Todo items that have been completed and a
        <literal>remaining()</literal> filter for those that are still
        outstanding.
      </para>
      <para>
        <emphasis role="strong">collections/todos.js</emphasis>
      </para>
      <programlisting language="javascript">
define([
  'underscore',
  'backbone',
  'libs/backbone/localstorage',
  'models/todo'
  ], function(_, Backbone, Store, Todo){

    var TodosCollection = Backbone.Collection.extend({

    // Reference to this collection's model.
    model: Todo,

    // Save all of the todo items under the `&quot;todos&quot;` namespace.
    localStorage: new Store(&quot;todos&quot;),

    // Filter down the list of all todo items that are finished.
    done: function() {
      return this.filter(function(todo){ return todo.get('done'); });
    },

    // Filter down the list to only todo items that are still not finished.
    remaining: function() {
      return this.without.apply(this, this.done());
    },
    ...
</programlisting>
      <para>
        In addition to allowing users to add new Todo items from views
        (which we then insert as models in a collection), we ideally
        also want to be able to display how many items have been
        completed and how many are remaining. We’ve already defined
        filters that can provide us this information in the above
        collection, so let’s use them in our main application view.
      </para>
      <para>
        <emphasis role="strong">views/app.js</emphasis>
      </para>
      <programlisting language="javascript">
define([
  'jquery',
  'underscore',
  'backbone',
  'collections/todos',
  'views/todos',
  'text!templates/stats.html'
  ], function($, _, Backbone, Todos, TodoView, statsTemplate){

  var AppView = Backbone.View.extend({

    // Instead of generating a new element, bind to the existing skeleton of
    // the App already present in the HTML.
    el: $(&quot;#todoapp&quot;),

    // Our template for the line of statistics at the bottom of the app.
    statsTemplate: _.template(statsTemplate),

    // ...events, initialize() etc. can be seen in the complete file

    // Re-rendering the App just means refreshing the statistics -- the rest
    // of the app doesn't change.
    render: function() {
      var done = Todos.done().length;
      this.$('#todo-stats').html(this.statsTemplate({
        total: Todos.length,
        done: Todos.done().length,
        remaining: Todos.remaining().length
      }));
    },
    ...
</programlisting>
      <para>
        Above, we map the second template for this project,
        <literal>templates/stats.html</literal> to
        <literal>statsTemplate</literal> which is used for rendering the
        overall <literal>done</literal> and <literal>remaining</literal>
        states. This works by simply passing our template the length of
        our overall Todos collection (<literal>Todos.length</literal> -
        the number of Todo items created so far) and similarly the
        length (counts) for items that have been completed
        (<literal>Todos.done().length</literal>) or are remaining
        (<literal>Todos.remaining().length</literal>).
      </para>
      <para>
        The contents of our <literal>statsTemplate</literal> can be seen
        below. It’s nothing too complicated, but does use ternary
        conditions to evaluate whether we should state there’s <quote>1
        item</quote> or <quote>2 item<i>s</i></quote> in a particular
        state.
      </para>
      <programlisting>
&lt;% if (total) { %&gt;
        &lt;span class=&quot;todo-count&quot;&gt;
          &lt;span class=&quot;number&quot;&gt;&lt;%= remaining %&gt;&lt;/span&gt;
          &lt;span class=&quot;word&quot;&gt;&lt;%= remaining == 1 ? 'item' : 'items' %&gt;&lt;/span&gt; left.
        &lt;/span&gt;
      &lt;% } %&gt;
      &lt;% if (done) { %&gt;
        &lt;span class=&quot;todo-clear&quot;&gt;
          &lt;a href=&quot;#&quot;&gt;
            Clear &lt;span class=&quot;number-done&quot;&gt;&lt;%= done %&gt;&lt;/span&gt;
            completed &lt;span class=&quot;word-done&quot;&gt;&lt;%= done == 1 ? 'item' : 'items' %&gt;&lt;/span&gt;
          &lt;/a&gt;
        &lt;/span&gt;
      &lt;% } %&gt;
</programlisting>
      <para>
        The rest of the source for the Todo app mainly consists of code
        for handling user and application events, but that rounds up
        most of the core concepts for this practical.
      </para>
      <para>
        To see how everything ties together, feel free to grab the
        source by cloning this repo or browse it
        <ulink url="https://github.com/addyosmani/backbone-fundamentals/tree/master/practicals/modular-todo-app">online</ulink>
        to learn more. I hope you find it helpful!.
      </para>
      <para>
        <emphasis role="strong">Note:</emphasis> While this first
        practical doesn’t use a build profile as outlined in the chapter
        on using the RequireJS optimizer, we will be using one in the
        section on building mobile Backbone applications.
      </para>
    </sect3>
  </sect2>
  <sect2 id="decoupling-backbone-with-the-mediator-and-facade-patterns">
    <title><a name="decouplingbackbone">Decoupling Backbone with the
    Mediator and Facade patterns</a></title>
    <para>
      In this section we’ll discuss applying some of the concepts I
      cover in my article on
      <ulink url="http://addyosmani.com/largescalejavascript">Large-scale
      JavaScript Application development</ulink> to Backbone.
    </para>
    <sect3 id="summary-1">
      <title>Summary</title>
      <para>
        At a high-level, one architecture that works for such
        applications is something which is:
      </para>
      <itemizedlist>
        <listitem>
          <para>
            <emphasis role="strong">Highly decoupled</emphasis>:
            encouraging modules to only publish and subscribe to events
            of interest rather than directly communicating with each
            other. This helps us to build applications who’s units of
            code aren’t highly tied (coupled) together and can thus be
            reused more easily.
          </para>
        </listitem>
        <listitem>
          <para>
            <emphasis role="strong">Supports module-level
            security</emphasis>: whereby modules are only able to
            execute behavior they’ve been permitted to. Application
            security is an area which is often overlooked in JavaScript
            applications, but can be quite easily implemented in a
            flexible manner.
          </para>
        </listitem>
        <listitem>
          <para>
            <emphasis role="strong">Supports failover</emphasis>:
            allowing an application continuing to function even if
            particular modules fail. The typical example I give of this
            is the GMail chat widget. Imagine being able to build
            applications in a way that if one widget on the page fails
            (e.g chat), the rest of your application (mail) can continue
            to function without being affected.
          </para>
        </listitem>
      </itemizedlist>
      <para>
        This is an architecture which has been implemented by a number
        of different companies in the past, including Yahoo! (for their
        modularized homepage - which Nicholas Zakas has
        <ulink url="http://www.youtube.com/watch?v=vXjVFPosQHw">spoken</ulink>
        about) and AOL for some of our upcoming projects.
      </para>
      <para>
        The three design patterns that make this architecture possible
        are the:
      </para>
      <itemizedlist>
        <listitem>
          <para>
            <emphasis role="strong">Module pattern</emphasis>: used for
            encapsulating unique blocks of code, where functions and
            variables can be kept either public or private.
            (<quote>private</quote> in the simulation of privacy sense,
            as of course don’t have true privacy in JavaScript)
          </para>
        </listitem>
        <listitem>
          <para>
            <emphasis role="strong">Mediator pattern</emphasis>: used
            when the communication between modules may be complex, but
            is still well defined. If it appears a system may have too
            many relationships between modules in your code, it may be
            time to have a central point of control, which is where the
            pattern fits in.
          </para>
        </listitem>
        <listitem>
          <para>
            <emphasis role="strong">Facade pattern</emphasis>: used for
            providing a convenient higher-level interface to a larger
            body of code, hiding its true underlying complexity
          </para>
        </listitem>
      </itemizedlist>
      <para>
        Their specific roles in this architecture can be found below.
      </para>
      <itemizedlist>
        <listitem>
          <para>
            <emphasis role="strong">Modules</emphasis>: There are almost
            two concepts of what defines a module. As AMD is being used
            as a module wrapper, technically each model, view and
            collection can be considered a module. We then have the
            concept of modules being distinct blocks of code outside of
            just MVC/MV*. For the latter, these types of
            <quote>modules</quote> are primarily concerned with
            broadcasting and subscribing to events of interest rather
            than directly communicating with each other.They are made
            possible through the Mediator pattern.
          </para>
        </listitem>
        <listitem>
          <para>
            <emphasis role="strong">Mediator</emphasis>: The mediator
            has a varying role depending on just how you wish to
            implement it. In my article, I mention using it as a module
            manager with the ability to start and stop modules at will,
            however when it comes to Backbone, I feel that simplifying
            it down to the role of a central <quote>controller</quote>
            that provides pub/sub capabilities should suffice. One can
            of course go all out in terms of building a module system
            that supports module starting, stopping, pausing etc,
            however the scope of this is outside of this chapter.
          </para>
        </listitem>
        <listitem>
          <para>
            <emphasis role="strong">Facade</emphasis>: This acts as a
            secure middle-layer that both abstracts an application core
            (Mediator) and relays messages from the modules back to the
            Mediator so they don’t touch it directly. The Facade also
            performs the duty of application security guard; it checks
            event notifications from modules against a configuration
            (permissions.js, which we will look at later) to ensure
            requests from modules are only processed if they are
            permitted to execute the behavior passed.
          </para>
        </listitem>
      </itemizedlist>
      <para>
        For ease of reference, I sometimes refer to these three patterns
        grouped together as Aura (a word that means subtle, luminous
        light).
      </para>
    </sect3>
    <sect3 id="practical-2">
      <title>Practical</title>
      <para>
        For the practical section of this chapter, we’ll be extending
        the well-known Backbone Todo application using the three
        patterns mentioned above. The complete code for this section can
        be found here: https://github.com/addyosmani/backbone-aura and
        should ideally be run on at minimum, a local HTTP server.
      </para>
      <para>
        The application is broken down into AMD modules that cover
        everything from Backbone models through to application-level
        modules. The views publish events of interest to the rest of the
        application and modules can then subscribe to these event
        notifications.
      </para>
      <para>
        All subscriptions from modules go through a facade (or sandbox).
        What this does is check against the subscriber name and the
        <quote>channel/notification</quote> it’s attempting to subscribe
        to. If a channel <emphasis>doesn’t</emphasis> have permissions
        to be subscribed to (something established through
        permissions.js), the subscription isn’t permitted.
      </para>
      <para>
        <emphasis role="strong">Mediator</emphasis>
      </para>
      <para>
        Found in <literal>aura/mediator.js</literal>
      </para>
      <para>
        Below is a very simple AMD-wrapped implementation of the
        mediator pattern, based on prior work by Ryan Florence. It
        accepts as it’s input an object, to which it attaches
        <literal>publish()</literal> and <literal>subscribe()</literal>
        methods. In a larger application, the mediator can contain
        additional utilities, such as handlers for initializing,
        starting and stopping modules, but for demonstration purposes,
        these two methods should work fine for our needs.
      </para>
      <programlisting language="javascript">
define([], function(obj){

  var channels = {};
  if (!obj) obj = {};

  obj.subscribe = function (channel, subscription) {
    if (!channels[channel]) channels[channel] = [];
    channels[channel].push(subscription);
  };

  obj.publish = function (channel) {
    if (!channels[channel]) return;
    var args = [].slice.call(arguments, 1);
    for (var i = 0, l = channels[channel].length; i &lt; l; i++) {
      channels[channel][i].apply(this, args);
    }
  };

  return obj;

});
</programlisting>
      <para>
        <emphasis role="strong">Facade</emphasis>
      </para>
      <para>
        Found in <literal>aura/facade.js</literal>
      </para>
      <para>
        Next, we have an implementation of the facade pattern. Now the
        classical facade pattern applied to JavaScript would probably
        look a little like this:
      </para>
      <programlisting language="javascript">

var module = (function() {
    var _private = {
        i:5,
        get : function() {
            console.log('current value:' + this.i);
        },
        set : function( val ) {
            this.i = val;
        },
        run : function() {
            console.log('running');
        },
        jump: function(){
            console.log('jumping');
        }
    };
    return {
        facade : function( args ) {
            _private.set(args.val);
            _private.get();
            if ( args.run ) {
                _private.run();
            }
        }
    }
}());

module.facade({run: true, val:10});
//outputs current value: 10, running
</programlisting>
      <para>
        It’s effectively a variation of the module pattern, where
        instead of simply returning an interface of supported methods,
        your API can completely hide the true implementation powering
        it, returning something simpler. This allows the logic being
        performed in the background to be as complex as necessary,
        whilst all the end-user experiences is a simplified API they
        pass options to (note how in our case, a single method
        abstraction is exposed). This is a beautiful way of providing
        APIs that can be easily consumed.
      </para>
      <para>
        That said, to keep things simple, our implementation of an
        AMD-compatible facade will act a little more like a proxy.
        Modules will communicate directly through the facade to access
        the mediator’s <literal>publish()</literal> and
        <literal>subscribe()</literal> methods, however, they won’t as
        such touch the mediator directly.This enables the facade to
        provide application-level validation of any subscriptions and
        publications made.
      </para>
      <para>
        It also allows us to implement a simple, but flexible,
        permissions checker (as seen below) which will validate
        subscriptions made against a permissions configuration to see
        whether it’s permitted or not.
      </para>
      <programlisting language="javascript">
define([ &quot;../aura/mediator&quot; , &quot;../aura/permissions&quot; ], function (mediator, permissions) {

    var facade = facade || {};

    facade.subscribe = function(subscriber, channel, callback){

        // Note: Handling permissions/security is optional here
        // The permissions check can be removed
        // to just use the mediator directly.

        if(permissions.validate(subscriber, channel)){
            mediator.subscribe( channel, callback );
        }
    }

    facade.publish = function(channel){
        mediator.publish( channel );
    }
    return facade;

});
</programlisting>
      <para>
        <emphasis role="strong">Permissions</emphasis>
      </para>
      <para>
        Found in <literal>aura/permissions.js</literal>
      </para>
      <para>
        In our simple permissions configuration, we support checking
        against subscription requests to establish whether they are
        allowed to clear. This enforces a flexible security layer for
        the application.
      </para>
      <para>
        To visually see how this works, consider changing say,
        permissions -&gt; renderDone -&gt; todoCounter to be false. This
        will completely disable the application from from rendering or
        displaying the counts component for Todo items left (because
        they aren’t allowed to subscribe to that event notification).
        The rest of the Todo app can still however be used without
        issue.
      </para>
      <para>
        It’s a very dumbed down example of the potential for application
        security, but imagine how powerful this might be in a large app
        with a significant number o