Mulib/Examples

= 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":
# 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))
=== CGI ===
You can treat this resource as a CGI, by writing a second, wrapper, file that refers to it:
# hello_world.cgi:
#!/usr/bin/python
from mulib import cgiadapter
cgiadapter.run_as_cgi('hello_world', 'HelloWorld')
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.
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))
You can then access this dictionary as a REST resource, e.g.
<nowiki>
 > 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
</nowiki>
Mu/stacked can do content negotiation:
<nowiki>
 > 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'}
</nowiki>
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:
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
}
# Start the server
httpd.server(
 api.tcp_listener(('0.0.0.0', 5000)),
 mu.SiteMap(root), max_http_version="HTTP/1.0"
)
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>
 
 Web Chat 
 
 
 
 
 
 
 <input type="text" maxlength="256" id="chat_message"/>
 
 </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