Question

I hear that I can use Comet as a server push technology along with my Ajax code to increase the performance of my web applications.

How mature this Comet technology?

Is it supported by all web servers, programming languages and browsers?

What are the disadvantages of using Comet?

Answer 1

It is mature, though I think you should consider it more of a technique than a technology.

All web servers support it as far as I know, though you will need to research and configure your particular web server if you are building a comet application as the demands on the resources are a bit different. Specifically, there will be far more simultaneous open connections to your server. In terms of programming language support, if your server language of choice has any sort of blocking or waiting mechanism, you can support server-push. All browsers support it as well, as from the perspective of a browser, this is simply an http(s) connection that takes a long time to return.

There are a couple of disadvantages, in the browser world, the biggest is probably the fact that some browsers limit the number of open connections to a specific URL to two. So if you have a server blocking connection open waiting for some pushed data, you are down to only one connection available for the browser to get data from the server. This can be mitigated by spreading your resources over a few second level domains to allow the browser to open more connections.