Mulib/Examples

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Mulib Examples

These are some short examples to give a flavor of using mulib. You can find all the example code in the examples directory of a mulib checkout.

hello world

The following program will bring up a webserver listening on port 8080 which can respond to a single request, "GET /", with the response "hello, world":

<python># hello_world.py: from mulib import mu

from eventlet import api, httpd

class HelloWorld(mu.Resource):

   def handle_get(self, req):
       req.write("hello, world\n")


if __name__ == "__main__":

   root = HelloWorld()
   httpd.server(
       api.tcp_listener(('0.0.0.0', 8080)),
       mu.SiteMap(root))</python>

CGI

You can treat this resource as a CGI, by writing a second, wrapper, file that refers to it:

<python># hello_world.cgi:

  1. !/usr/bin/python

from mulib import cgiadapter

cgiadapter.run_as_cgi('hello_world', 'HelloWorld')</python>

Configure your web server to execute hello_world.cgi, and you should be able to interact with it just like the standalone version.

stacked

Stacked is a pure REST server, and you can use it to traverse native python objects like dicts. You invoke these special capabilities of Stacked by placing a python dict or list in the resource hierarchy instead of a mu.Resource, in this case at the root.

<python>from mulib import mu

from eventlet import api, httpd

root = {:'hello, world\n',

       'other':"hello, other\n"}

httpd.server(api.tcp_listener(('0.0.0.0', 8080)), mu.SiteMap(root))</python>

You can then access this dictionary as a REST resource, e.g.

 > curl http://localhost:8080/     
 hello, world
 > curl http://localhost:8080/other
 hello, other
 > curl -X PUT -d "the new data" http://localhost:8080/third
 > curl http://localhost:8080/third
 the new data

Mu/stacked can do content negotiation:

 > curl -X PUT -H "Content-type: application/json" -d '{"hi": "there"}' http://localhost:8080/fourth
 > curl http://localhost:8080/fourth/hi
 there
 > curl -H "Accept: application/json" http://localhost:8080/fourth
 {'hi': 'there'}

Note: This means that anyone who has access to your stacked web service can modify the data in your process! In the future we might have a 'read-only' implementation.

Chat Server

EvilChuck wrote a nifty toy chat server that we will partially reproduce here at his permission.

Through stacked, and coros, we can tie a ChatMessage instance to the /listen url:

<python> from mulib import mu, stacked, resources from eventlet import api, httpd, coros, util

util.wrap_socket_with_coroutine_socket()

chat_listener = coros.event()

class ChatMessage(mu.Resource):

   """A Resource to handle receiving chat messages"""
   def handle_post(self, request):
       """POST to send chat messages
       expects nick and message as POST arguments"""
       nick = request.get_arg('nick')
       message = request.get_arg('message').strip()
       if message:
           # Send the chat message to all who are listening
           chat_listener.send("%s: %s" % (nick, message))
           # Reset the listener so that it can receive more messages 
           chat_listener.reset()
       request.write()

root = {

       'chat' : resources.File('chat.html'),   # /chat -> Load chat.html
       'listen' : chat_listener,               # /listen -> Wait for new msgs 
       'message' : ChatMessage(),              # /message -> Send a message

}

  1. Start the server

httpd.server(

   api.tcp_listener(('0.0.0.0', 5000)),
   mu.SiteMap(root), max_http_version="HTTP/1.0"

) </python>

And with some fancy html which is served up through the resources.File we get:

<html>
  <head>
    <link rel="stylesheet" href="http://yui.yahooapis.com/2.4.1/build/reset-fonts-grids/reset-fonts-grids.css" type="text/css"> 
    <style>
      #hd, #bd, #ft { border: 1px solid #808080;}
      #hd h1 { margin-left: 5px; font-size: 120%; }
      #bd { min-height: 350px; }
      body { position: relative; }
      .bd { text-align: left; }
      input { width: 100%; }
    </style>
  </head>
  <body>
  <div id="doc" class="yui-t7"> 
    <div id="hd"><h1>Web Chat</h1></div> 
    <div id="bd"> 
      <div class="yui-g"> 
        <div id="chat_text"></div>
      </div> 
    </div>
    <div id="ft">
      <input type="text" maxlength="256" id="chat_message"/>
    </div> 
  </body>
  <script src="http://yui.yahooapis.com/2.4.1/build/yahoo/yahoo-min.js"></script> 
  <script src="http://yui.yahooapis.com/2.4.1/build/event/event-min.js" ></script>
  <script src="http://yui.yahooapis.com/2.4.1/build/dom/dom-min.js"></script>
  <script src="http://yui.yahooapis.com/2.4.1/build/connection/connection-min.js"></script>
  <script type="text/javascript">
    YAHOO.util.Event.onDOMReady(function () {
      // Set up a random nickname for the user
      var nick = 'User-' + Math.round(Math.random()*10000);
      var handleReturn = function (type, args, obj) {
        // Handler to run when the Enter key is pressed
        var el = document.getElementById("chat_message");
        if (el.value) {
          // Send the message to the server
          var postData = "nick="+escape(nick)+"&message="+escape(el.value);
          YAHOO.util.Connect.asyncRequest('POST','/message', {
            success : function(o) {
              el.value = '';
              },
          }, postData);
        }
      };
      var listen = function () {
        // Listens for incoming messages
        YAHOO.util.Connect.asyncRequest('GET', '/listen', {
          success: function (o) {
            if (o.status == 200) {
              var el = document.getElementById("chat_text");
              el.innerHTML += o.responseText + '<BR/>';
              listen();
            }
            else if (o.status == 202) {
              // 202 is returned when the connection has timed out
              listen();
            }
          }
        });
      };
      // Register the key listener to listen for the Enter key
      var keyListener = new YAHOO.util.KeyListener(
          document, {keys: 13}, handleReturn);
      keyListener.enable();
      // Start listening for incoming messages
      listen();
    });
  </script>
</html>

To test it out, put both files in the same directory, launch chat.py, and browse to http://localhost:5000/chat