Comet.js v.0.5 - It's is a flexible long polling module for node.js with support for unlimited listener types, multi and single listeners, custom sender identification. It has mysql integration, and a simple API.

Dependencies

The module is based on the application framework and it uses mysql as a database handler.

A tiny chat client in less than 55 lines

Server side

You will need to include this in your server.js like use('comet.js')

	// REQUIRE comet module
	comet = new Comet({
		app		 : app,
		database : 'my_projects_database',
		id		 : function(request, response){ return request.cookies.sid; },
		sender	 : function(request, mysql, callback){ 
			mysql.users.getBy('id', request.cookies.id, function(users){
				callback(new User(users[0])); 
			});
		}
	});
	
	// COLLECT Listeners
	var everyone = [];
	comet.listener('home', function(request, package, mysql, options, end){
		end(everyone, options, false);
	});
	
	// JOIN event
	var join 		= comet.actions('join');
	join.onEmit 	= baseEmit
	join.onSubmit 	= function(mysql, request, response, package, private, listener, end){
		everyone.push(request.cookies.id);
		end();
	}
	
	// LEAVE event
	var leave 		= comet.actions('leave');
	leave.onEmit 	= baseEmit;
	leave.onSubmit 	= function(mysql, request, response, package, private, listener, end){
		everyone.remove(request.cookies.id);
		end();
	}

Client Side

You will have to include the auto generated /scripts/comet.js

	<script src="/scripts/comet.js" type="text/javascript"></script>

	<script>
		window.onload = function(){
			// PUSH join
			comet.push({ type: 'join', listeners: ['home'] });
			
			// PUSH messages
			comet.push({ type: 'message', listeners: ['home'], message: 'Hello World!' });
			comet.push({ type: 'message', listeners: ['home'], message: 'This is comet.js!' });
		}
		
		// PUSH leave
		window.onunload = function(){
			comet.push({ type: 'leave', listeners: ['home'] });
		}
	
		// LISTEN on join, leave and message events
		comet.ping.join 	= function(package){ console.log('joined', package); }
		comet.ping.leave 	= function(package){ console.log('leaved', package); }
		comet.ping.message 	= function(package){ console.log(package.sender, ' -> ', package.message); }
	</script>

Server side module variables

app: object required

• an Application() Object

database: string required

• custom mysql database name

id: function required

• internal sender ID identifier
• this can be a string or a number, it is usually the request.cookies.id

sender: function required

• overall sender identifier
• this can be anything, but it's usually a user Object with name, location etc..
• it is usually used on the receivers side to show who sent the message

emitOnEndFilter: function optional

• a filter function which runs just before the emit, which has the right to pass or stop the emit event
• it can be used for ignore list filtering

Client side implementaton

When you use the comet module on server side, a path for the client side js file will be generated in your public/scripts/comet.client what you can include in your html file like this:

	<script src="/scripts/comet.js" type="text/javascript"></script>

After you included the comet.js file you will have access to the global comet object.

Initializing:

	comet.controller(); 			// start the controller
	setTimeout(comet.worker, 1000); // starts the worker 1 second later for safety

After you initialized you don't have to worry about anything except sending and receiving information in real-time with push function and ping object.

comet.push(package)

This function broadcasts a message with the specified package:

• type : This is a custom type of the message action string required
• listeners : If it's an array then it will be sent to a group of people, if it's a string or an intenger then it will be sent to that single client. string, integer or array required
• parameters : whatever else you put in the package it is considered as package parameters. optional anything

An example push request:

	comet.push({
		type: 'join',
		listeners: ['family'],
		my_custom_message: 'Hi family members!'
	})

comet.ping

This is where you can assign listeners to the actions, for example you can listen to the join event above with:

	comet.ping.join = function(package){
		console.log(package) 
		// output => { type: 'join', listeners: ['family'], my_custom_message: 'Hi family members!' }
	}

Versions

New in v0.5 - (February 13, 2013):

• Automatic client js path app.public+/scripts/comet.client
• Submit Before Emit Introduced
• New comet.action interface to support submit_before_emit
• Each package now is stamped with a Unique Package ID (package._stamp)
• Each request is stamped with a request.comet_id by COMET.id()
• Improved documentation

New in v0.4 - (October 3, 2012):

• Totally stand-alone module
• Accepts variables
• Cleaned-up inner module interface

New in v0.3 - (Summer 2012):

• Half stand alone module
• Pressure control with Controller/workers mechanism
• 99% message transmission success
• Several bug fixes
• Custom listeners

New in v0.2 - (Spring 2012)

• Private object in package
• Server side comet.push()
• Better & stand alone client-side comet modules

New in v0.1 - (Summer 2011):

• Custom message types

TODO

• Support database handlers other than mysql
• Shortcuts for messaging channels, like create a new channel instance with already setup join, leave, create, update, delete types and register the channel listener.