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[docs] add middleware examples (first draft)

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1 parent f7452bc commit 020290a162146c4996831f4f13d71c1dc949f508 @dominictarr dominictarr committed Jul 30, 2011
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  1. +97 −0 examples/bodyDecoder-middleware.js
  2. +30 −0 examples/jsonp-middleware.js
  3. +88 −0 examples/url-middleware2.js
@@ -0,0 +1,97 @@
+
+var Store = require('./lib/store')
+ , http = require('http')
+
+http.createServer(new Store().handler()).listen(7531, function () {
+//try these commands:
+// get index:
+// curl localhost:7531
+// []
+//
+// get a doc:
+// curl localhost:7531/foo
+// {"error":"not_found"}
+//
+// post an doc:
+// curl -X POST localhost:7531/foo -d '{"content": "hello", "type": "greeting"}'
+// {"ok":true}
+//
+// get index (now, not empty)
+// curl localhost:7531
+// ["/foo"]
+//
+// get doc
+// curl localhost:7531/foo
+// {"content": "hello", "type": "greeting"}
+
+//
+// now, suppose we wanted to direct all objects where type == "greeting" to a different store
+// than where type == "insult"
+//
+// we can use connect connect-bodyDecoder and some custom logic to send insults to another Store.
+
+//insult server:
+
+ http.createServer(new Store().handler()).listen(2600, function () {
+
+ //greetings -> 7531, insults-> 2600
+
+ // now, start a proxy server.
+
+ var bodyParser = require('connect/lib/middleware/bodyParser')
+ //don't worry about incoming contont type
+ //bodyParser.parse[''] = JSON.parse
+
+ require('http-proxy').createServer(
+ //refactor the body parser and re-streamer into a separate package
+ bodyParser(),
+ //body parser absorbs the data and end events before passing control to the next
+ // middleware. if we want to proxy it, we'll need to re-emit these events after
+ //passing control to the middleware.
+ function (req, res, next) {
+ //remove bodyParser's listeners
+ req.removeAllListeners('data')
+ req.removeAllListeners('end')
+ next()
+ process.nextTick(function () {
+ if(req.body)
+ req.emit('data', JSON.stringify(req.body))
+ req.emit('end')
+ })
+ },
+ function (req, res, proxy) {
+ //if your posting an obect which contains type: "insult"
+ //it will get redirected to port 2600.
+ //normal get requests will go to 7531 nad will not return insults.
+ var port = (req.body && req.body.type === 'insult' ? 2600 : 7531)
+ proxy.proxyRequest(req, res, {host: 'localhost', port: port})
+ }
+ ).listen(1337, function () {
+ var request = require('request')
+ //bodyParser needs content-type set to application/json
+ //if we use request, it will set automatically if we use the 'json:' field.
+ function post (greeting, type) {
+ request.post({
+ url: 'http://localhost:1337/' + greeting,
+ json: {content: greeting, type: type || "greeting"}
+ })
+ }
+ post("hello")
+ post("g'day")
+ post("kiora")
+ post("houdy")
+ post("java", "insult")
+
+ //now, the insult should have been proxied to 2600
+
+ //curl localhost:2600
+ //["/java"]
+
+ //but the greetings will be sent to 7531
+
+ //curl localhost:7531
+ //["/hello","/g%27day","/kiora","/houdy"]
+
+ })
+ })
+})
@@ -0,0 +1,30 @@
+var Store = require('./lib/store')
+ , http = require('http')
+
+//
+// jsonp is a handy technique for getting around the limitations of the same-origin policy.
+// (http://en.wikipedia.org/wiki/Same_origin_policy)
+//
+// normally, to dynamically update a page you use an XmlHttpRequest. this has flakey support
+// is some browsers and is restricted by the same origin policy. you cannot perform XHR requests to
+// someone else's server. one way around this would be to proxy requests to all the servers you want
+// to xhr to, and your core server - so that everything has the same port and host.
+//
+// another way, is to turn json into javascript. (which is exempt from the same origin policy)
+// this is done by wrapping the json object in a function call, and then including a script tag.
+//
+// here we're proxing our own JSON returning server, but we could proxy any server on the internet,
+// and our client side app would be slurping down JSONP from anywhere.
+//
+// curl localhost:1337/whatever?callback=alert
+// alert([]) //which is valid javascript!
+//
+// also see http://en.wikipedia.org/wiki/JSONP#JSONP
+//
+
+http.createServer(new Store().handler()).listen(7531)
+
+require('http-proxy').createServer(
+ require('connect-jsonp')(true),
+ 'localhost', 7531
+).listen(1337)
@@ -0,0 +1,88 @@
+var util = require('util'),
+ colors = require('colors'),
+ http = require('http'),
+ httpProxy = require('http-proxy'),
+ Store = require('./lib/store')
+//
+// This is an example of a url-routing middleware.
+// This is not intended for production use, but rather as
+// an example of how to write a middleware.
+//
+
+function matcher (url, dest) {
+ // First, turn the URL into a regex.
+ // NOTE: Turning user input directly into a Regular Expression is NOT SAFE.
+ var r = new RegExp(url.replace(/\//, '\\/'));
+ // This next block of code may look a little confusing.
+ // It returns a closure (anonymous function) for each URL to be matched,
+ // storing them in an array - on each request, if the URL matches one that has
+ // a function stored for it, the function will be called.
+ return function (url) {
+ var m = r(url)
+ if (!m) {
+ return;
+ }
+ var path = url.slice(m[0].length);
+ console.log('proxy:', url, '->', dest);
+ return {url: path, dest: dest};
+ }
+}
+
+exports.urls = function (urls) {
+ // This is the entry point for our middleware.
+ // 'matchers' is the array of URL matchers, as mentioned above.
+ var matchers = [];
+ for (var url in urls) {
+ // Call the 'matcher' function above, and store the resulting closure.
+ matchers.push(matcher(url, urls[url]));
+ }
+
+ // This closure is returned as the request handler.
+ return function (req, res, next) {
+ //
+ // in node-http-proxy middlewares, `proxy` is the prototype of `next`
+ // (this means node-http-proxy middlewares support both the connect API (req, res, next)
+ // and the node-http-proxy API (req, res, proxy)
+ //
+ var proxy = next;
+ for (var k in matchers) {
+ // for each URL matcher, try the request's URL.
+ var m = matchers[k](req.url);
+ // If it's a match:
+ if (m) {
+ // Replace the local URL with the destination URL.
+ req.url = m.url;
+ // If routing to a server on another domain, the hostname in the request must be changed.
+ req.headers.host = m.host;
+ // Once any changes are taken care of, this line makes the magic happen.
+ proxy.proxyRequest(req, res, m.dest);
+ }
+ }
+ }
+}
+
+http.createServer(new Store().handler()).listen(7531)
+
+// Now we set up our proxy.
+httpProxy.createServer(
+ // This is where our middlewares go, with any options desired - in this case,
+ // the list of routes/URLs and their destinations.
+ exports.urls({
+ '/store': { port: 7531, host: 'localhost' },
+ '/': { port: 9000, host: 'localhost' }
+ })
+).listen(8000);
+
+//
+// Target Http Server (to listen for requests on 'localhost')
+//
+http.createServer(
+ function (req, res) {
+ res.writeHead(200, { 'Content-Type': 'text/plain' });
+ res.write('request successfully proxied to: ' + req.url + '\n' + JSON.stringify(req.headers, true, 2));
+ res.end();
+ }).listen(9000);
+
+// And finally, some colored startup output.
+util.puts('http proxy server'.blue + ' started '.green.bold + 'on port '.blue + '8000'.yellow);
+util.puts('http server '.blue + 'started '.green.bold + 'on port '.blue + '9000 '.yellow);

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