Simple comet example using php and jquery

Question

You should use polling, or use a web server which is specially conceived for long requests and COMET, with a good JS backend:

function listen() {
    $.get("/mylongrequestfile", {}, function(data) {
        $("#mydiv").html(data);
        listen(); // then launch again
    }));
};

Remember that COMET is "wait for data, if there's data return and exit", so JS backend will have to parse the data and re-launch the process of asking the server.

In this example, if there is a server side problem or just a disconnection from the user side, the entire process will be broken (the function is only called if the request is successful)

Check this out: How to implement COMET with PHP.
This is not using JQuery. It is made using PHP and Prototype. It is very easy to understand. I think you can made JQuery script easily after viewing this.

I have a very simple example here that can get you started with comet. It covers compiling Nginx with the NHPM module and includes code for simple publisher/subscriber roles in jQuery, PHP, and Bash.

http://blog.jamieisaacs.com/2010/08/27/comet-with-nginx-and-jquery/

A working example (simple chat) can be found here:
http://cheetah.jamieisaacs.com/

Never having used this technique and studying the Wikipedia article on the topic, "Long Polling" seems like the only viable solution. It sounds pretty simple to implement by infinitely looping and sleeping a script on the server. There's some actual code in the HTTP Streaming page linked to from the Wikipedia article.

Have you tried any of this and stumbled on specific problems?

Check out this demo video for implementing Long Polling ( comet ).. It might help you all

http://www.screenr.com/SNH

You can take a look at this article, it's a really good start to understand comet programming concepts.

You will find two examples on it. The first one use the iframe technique whereas the second one use a persistent connection.