forked from webmachine/webmachine
-
Notifications
You must be signed in to change notification settings - Fork 27
/
example_resources.html
250 lines (219 loc) · 7.12 KB
/
example_resources.html
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
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta name="author" content="Basho Technologies" />
<meta name="description" content="Webmachine examples" />
<meta name="keywords" content="webmachine http rest web" />
<meta http-equiv="content-type" content="text/html;charset=utf-8" />
<link rel="stylesheet" href="css/style-1c.css" type="text/css" />
<title>Webmachine examples</title>
</head>
<body>
<div id="content">
<h1><span class="hr"></span><a href="/">webmachine</a></h1>
<ul id="top">
<li><a href="/">Home</a></li>
<li><a href="http://bitbucket.org/justin/webmachine/">Source Code</a></li>
<li><a href="contact.html">Contact</a></li>
</ul>
<div id="left">
<h3>Webmachine examples</h3>
<p>
The simplest possible example is the one produced via the
<a href="quickstart.html">quickstart</a>.
</p>
<p>
For an example of a read/write filesystem server showing several
interesting features and supporting GET, PUT, DELETE, and POST, see
<a href="http://bitbucket.org/justin/webmachine/src/tip/demo/src/demo_fs_resource.erl">demo_fs_resource</a>.
</p>
<p>
For a very simple resource demonstrating content negotiation, basic
auth, and some caching headers, see
<a href="http://bitbucket.org/justin/webmachine/src/tip/demo/src/webmachine_demo_resource.erl">webmachine_demo_resource</a>.
</p>
<p>
Some example code based on webmachine_demo_resource follows.
</p>
<p>
The simplest working resource could export only one function in
addition to init/1:
</p>
<pre>
-module(webmachine_demo_resource).
-export([init/1, to_html/2]).
-include_lib("webmachine/include/webmachine.hrl").
init([]) -> {ok, undefined}.
to_html(ReqData, Context) -> {"<html><body>Hello, new world</body></html>", ReqData, Context}.
</pre>
<p>
That's really it -- a working webmachine resource. That resource will
respond to all valid GET requests with the exact same response.
</p>
<p>
Many interesting bits of HTTP are handled automatically by
Webmachine. For instance, if a client sends a request to that trivial
resource with an Accept header that does not allow for a text/html
response, they will receive a 406 Not Acceptable.
</p>
<p>
Suppose I wanted to serve a plaintext client as well. I could note
that I provide more than just HTML:
</p>
<pre>
content_types_provided(ReqData, Context) ->
{[{"text/html", to_html},{"text/plain",to_text}], ReqData, Context}.
</pre>
<p>
I already have my HTML representation produced, so I add a text one:
(and while I'm at it, I'll show that it's trivial to produce dynamic content as well)
</p>
<pre>
to_text(ReqData, Context) ->
Path = wrq:disp_path(ReqData),
Body = io_lib:format("Hello ~s from webmachine.~n", [Path]),
{Body, ReqData, Context}.
</pre>
<p>
Now that this resource provides multiple media types, it automatically performs conneg:
</p>
<pre>
$ telnet localhost 8000
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
GET /demo/a/resource/path HTTP/1.1
Accept: text/plain
HTTP/1.1 200 OK
Vary: Accept
Server: MochiWeb/1.1 WebMachine/0.97
Date: Sun, 15 Mar 2009 02:54:02 GMT
Content-Type: text/plain
Content-Length: 39
Hello a/resource/path from webmachine.
</pre>
<p>
What about authorization? Webmachine resources default to assuming the
client is authorized, but that can easily be overridden. Here's an
overly simplistic but illustrative example:
</p>
<pre>
is_authorized(ReqData, Context) ->
case wrq:disp_path(ReqData) of
"authdemo" ->
case wrq:get_req_header("authorization", ReqData) of
"Basic "++Base64 ->
Str = base64:mime_decode_to_string(Base64),
case string:tokens(Str, ":") of
["authdemo", "demo1"] ->
{true, ReqData, Context};
_ ->
{"Basic realm=webmachine", ReqData, Context}
end;
_ ->
{"Basic realm=webmachine", ReqData, Context}
end;
_ -> {true, ReqData, Context}
end.
</pre>
<p>
With that function in the resource, all paths except
<code>/authdemo</code> from this resource's root are authorized.
For that one path,
the UA will be asked to do basic authorization with the user/pass of
authdemo/demo1. It should go without saying that this isn't quite the
same function that we use in our real apps, but it is nice and simple.
</p>
<p>
If you've generated the application from the
<a href="quickstart.html">quickstart</a>, make sure
you've added this line to your dispatch.conf file:
</p>
<pre>
{["demo", '*'], mywebdemo_resource, []}.
</pre>
<p>
Now you can point your browser at
<code>http://localhost:8000/demo/authdemo</code> with the demo app running:
</p>
<pre>
$ curl -v http://localhost:8000/demo/authdemo
> GET /demo/authdemo HTTP/1.1
> Host: localhost:8000
> Accept: */*
>
< HTTP/1.1 401 Unauthorized
< WWW-Authenticate: Basic realm=webmachine
< Server: MochiWeb/1.1 WebMachine/0.97
< Date: Sun, 15 Mar 2009 02:57:43 GMT
< Content-Length: 0
<
</pre>
<p></p>
<pre>
$ curl -v -u authdemo:demo1 http://localhost:8000/demo/authdemo
* Server auth using Basic with user 'authdemo'
> GET /demo/authdemo HTTP/1.1
> Authorization: Basic YXV0aGRlbW86ZGVtbzE=
> Host: localhost:8000
> Accept: */*
>
< HTTP/1.1 200 OK
< Vary: Accept
< Server: MochiWeb/1.1 WebMachine/0.97
< Date: Sun, 15 Mar 2009 02:59:02 GMT
< Content-Type: text/html
< Content-Length: 59
<
<html><body>Hello authdemo from webmachine.
</body></html>
</pre>
<p>
HTTP caching support is also quite easy, with functions allowing
resources to define (e.g.) <code>last_modified</code>,
<code>expires</code>, and <code>generate_etag.</code> For instance, since
representations of this resource vary only by URI Path, I could use an
extremely simple entity tag unfit for most real applications but
sufficient for this example:
</p>
<pre>
generate_etag(ReqData, Context) -> {wrq:raw_path(ReqData), ReqData, Context}.
</pre>
<p>Similarly, here's a trivial expires rule:</p>
<pre>
expires(ReqData, Context) -> {{{2021,1,1},{0,0,0}}, ReqData, Context}.
</pre>
<p>
And now the response from our earlier request is appropriately tagged:
</p>
<pre>
HTTP/1.1 200 OK
Vary: Accept
Server: MochiWeb/1.1 WebMachine/0.97
Expires: Fri, 01 Jan 2021 00:00:00 GMT
ETag: /demo/authdemo
Date: Sun, 15 Mar 2009 02:59:02 GMT
Content-Type: text/html
Content-Length: 59
<html><body>Hello authdemo from webmachine.
</body></html>
</pre>
<p>
For more details, read the source of the resources linked at the top
of this page.
</p>
</div>
<div id="footer">
</div>
</div>
<script type="text/javascript">
var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");
document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
</script>
<script type="text/javascript">
try {
var pageTracker = _gat._getTracker("UA-4979965-5");
pageTracker._trackPageview();
} catch(err) {}</script>
</body>
</html>