Not There Yet: COMET with Apache and Jetty

Dietrich Kappe, Tuesday, May 16, 2006 @ 9:00 am

I had intended to marry the nice Apache2 event MPM and Jetty 6 with Continuations in order to achieve a thrifty, thread-sparing COMET capable Java app. The idea is that the Event MPM module in apache frees up a thread when an open connection to the browser is snoozing and Jetty frees up a thread when the backend servlet is snoozing. There are two problems, however.

1. The Event MPM module seems to only snooze between requests. With COMET the need to snooze happens during a requests, i.e. we are expecting something to come back from the server.
2. The request handler module -- in this case mod_jk or mod_proxy_ajp -- and not the Event MPM module handles the socket connections to the servlet container. From my reading of the most recent SVN branch, the modules are using blocking I/O and not polling.

It seems there's still a bit of work to be done to make Apache and Jetty do the COMET dance.

agile ajax

Comments: 2 so far

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1. 

   You could use ShortBus… when it’s ready.
   ShortBus is an HTTP based event system that runs inside of a reverse proxy (Perlbal). Apache wouldn’t be tied up by all the comet requests that are connected, and access is completly controlled by your own apps. Perlbal (and in turn ShortBus) can handle many thousands of connections.

   Comment by David Davis, Wednesday, May 17, 2006 @ 5:05 pm

2. 

   BTW, ShortBus is located at http://shortbus.xantus.org/

   Comment by David Davis, Wednesday, May 17, 2006 @ 5:06 pm

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