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Ajax polling.

Answer 1

+3 A:

What would you recommend?

XMPP through BOSH

There's no need to invent your own message format and transport protocol when somebody else has. If you try, it'll slowly grow to be just as complex as BOSH but without the benefit of third-party library support or standardization.

John Millikin 2008-08-30 00:22:22

Answer 2

+4 A:

You might also want to look into Comet.

It's used by GTalk, Meebo, and many other chat applications. A few years ago when I was experimenting with it, there weren't very many libraries or details about server architecture to implement it, but it looks like there is a lot more stuff out now.

Have a look at the cometd project for more technical information.

Ryan Guest 2008-08-30 00:29:37

Answer 3

A:

I thought everyone used cometd for this sort of thing.

hoyhoy 2008-08-30 01:54:36

Answer 4

+1 A:

You might also want to look into Comet.

I thought everyone used cometd for this sort of thing.

BOSH is a standard for transporting XMPP over HTTP. It involves Comet for pushing data to the client.

John Millikin 2008-08-30 02:04:27

Answer 5

A:

I did this very same thing a few months back and had fun just playing around with the concepts. I actually used the forever-frame technique instead of polling.

The below code is my "comet" js file that contains the general concepts required to get a "party chat" setup.

function Comet(key) {

  var random = key;
  var title = 'Comet';
  var connection = false;
  var iframediv = false;
  var browserIsIE = /*@cc_on!@*/false;
  var blurStatus = false;
  var tmpframe = document.createElement('iframe');
  var nl = '\r\n';

  this.initialize = function() {
    if (browserIsIE) {
      connection = new ActiveXObject("htmlfile");
      connection.open();
      connection.write("<html>");
      connection.write("<script>document.domain = '"+document.domain+"'");
      connection.write("</html>");
      connection.close();
      iframediv = connection.createElement("div");
      connection.appendChild(iframediv);
      connection.parentWindow.comet = comet;
      iframediv.innerHTML = "<iframe id='comet_iframe' src='./comet.aspx?key="+random+"'></iframe>";
    } else {
      connection = document.createElement('iframe');
      connection.setAttribute('id', 'comet_iframe');
      iframediv = document.createElement('iframe');
      iframediv.setAttribute('src', './comet.aspx?key='+random);
      connection.appendChild(iframediv);
      document.body.appendChild(connection);
    }
  }

  // this function is called from the server to keep the connection alive
  this.keepAlive = function () {
    if (!browserIsIE) {
        mozillaHack();
    }
  }

  // this function is called from the server to update the client
  this.updateClient = function (value) {
    var outputDiv = document.getElementById('output');
    outputDiv.value = value + nl + outputDiv.value;
    if (blurStatus == true) {
        document.title = value;
    }
    if (!browserIsIE) {
        mozillaHack();
    }
  }

  this.onUnload = function() {
    if (connection) {
      // this will release the iframe to prevent problems with IE when reloading the page
      connection = false;
    }
  }

  this.toggleBlurStatus = function(bool) {
    blurStatus = bool;
  }

  this.resetTitle = function() {
    document.title = title;
  }

  function mozillaHack() {
    // this hack will fix the hour glass and loading status for Mozilla browsers
    document.body.appendChild(tmpframe);
    document.body.removeChild(tmpframe);
  }
}

Toran Billups 2008-08-30 02:05:04

is this technique rquired to have tomcat add on third-on comet library ..etc ? or can be serve on typical servlet? is there any demo /working app we can refer to?

cometta 2009-09-01 09:42:43

can show us example of comet.aspx ?

cometta 2009-09-01 09:49:30

This technique doesn't require anything beyond IIS6 and .NET to get up and running.

Toran Billups 2009-09-01 12:46:37

Answer 6

A:

I agree with John. But there was another question that was not answered.
I have done this but instead of using a database we used a flat file, it did eventually cripple the server, but it wasn't until we has ~450 active users, and if we had done it with a database it probably would have fared better.
This was done on a basic hosting account from Godaddy.

Edit: BTW Godaddy sounded less then amused when I got the phone call.

Unkwntech 2008-08-30 02:52:11

Answer 7

A:

I think polling is the simplest approach and would recommend that first. If the load becomes a problem start, looking into more complicated techniques. A good discussion on the pros and cons are here - http://www.infoq.com/news/2007/07/pushvspull
http://ajaxian.com/archives/a-report-on-push-versus-pull

Jimmy 2008-09-21 14:31:09

Answer 8

+2 A:

There is a very good server for handling message pushing from server to browser (dubbed Comet) - Orbited. It's easily integrated with other technologies (Django, Rails, PHP etc.) just like memcached.

You really should check it if you want to handle serious load. Otherwise, simple Ajax polling is the best way.

zuber 2008-09-21 14:34:31

Answer 9

+1 A:

The trick is to realise that the only time your app needs to invoke CGI on the server is when someone says something. For the regular polls, poll a static page that your CGI script updates whenever there is new chat. Use HEAD requests, compare the timestamps with those last seen, and only do a full GET when those change. I have a simple naive chat application implemented this way, and the load and bandwidth usage is negligible for the few tens of simultaneous users we have.

moonshadow 2008-09-21 14:38:08

Answer 10

+3 A:

If you don't like the idea of HTTP-polling, you could have a Flash-movie on the chat page that has a constant connection to some deamon on the server, the Flash-movie would then invoke JavaScript functions on the client to update the chat as new messages comes along. (Unless you want a Flash interface for your chat..)

svinto 2008-09-21 16:09:21

Answer 11

A:

Checkout Speeqe. Its a open-source solution for Web-based chat rooms that uses BOSH and XMPP behind the scenes.

melo 2009-05-06 10:57:51

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