Re: push data from server to client web browser

[Thorbjørn Ravn Andersen <ravn@xxxxxxxxxx>]

john e skrev:
> http://en.wikipedia.org/wiki/Comet_(programming)
>
> It's a big hack, and therefore complex to implement and i don't know how scalable it is.
> But it seems to work (never tried it myself though).
>
>
>   
Any sufficiently advanced hack is indistinguishable from magic :)

It is very important to use a web server which is built to serve Comet 
applications, as you otherwise end up using one thread (or even worse - 
process) per outstanding idle request.

From http://www.webtide.com/downloads/whitePaperAjaxJetty.html which 
discuss the Jetty web server (which is a good alternative to Tomcat)

"The following table shows that a Web 1.0 server can handle 10000 users 
with 500 threads and 36MB of thread stacks, which is easily achievable 
with current JVMs and servers. For a Web 2.0 application these 
requirements explode an order of magnitude to 10600 threads and 694MB of 
stack memory, which is pushing the limits of current servers without 
even considering the resource requirements of the application:"

I know that the i scales well, but having to use over half a gigabyte of 
memory just to serve is a bit much :)