Paula Young wrote:
>
> one listener socket that listens for async
> notifications from the other host).
>
Servlets aren't really meant for that sort of thing.
Remember: the servlet (and session) are really only
guaranteed to be available while there's a request
coming in for the servlet. As soon as the request
is over, the servlet (or the session) might go away
for a while (or be moved to another machine, or be
partially recycled, etc) Or not. It's up to the
servlet container.
If you want a server thread, it's better to start up
another JVM and run the server where you have full
control.
The server thread can notify the servlet of updates
by just calling it using a URLConnection. That makes
things much cleaner all around. But it means running
another JVM.
If you feel you just have to spawn a thread from a
servlet, there are more details, and some links, at:
http://www.distributopia.com/servlet_stuff/background_threads.txt
> I've looked around for info on what types of objects are
> 'ok' to persist in the session and what types are definite
> no-nos, and couldn't find any info pro or con if persisting
> UNIX resources like sockets (connect and listen)in
> the session is even possible.
Check out the latest servlet spec, there's a section
called "Sessions" that has good, easy to read info.
Your problem (if I'm understanding correctly) is
similiar to the problem of keeping database connections
open across requests. So if you do some research about
how that works (connection per request, connection pools,
etc), most of it should apply. Try "connection pool" as
well as "resource pool" as search terms in google and
the archives of this list.
You've got to be careful. If the webapp is marked as
distributable, then a different machine might handle
the request every time, even for the same session, so
you're not going to be able to use the same socket. If
your webapp is not distributable, then you still need
to be very careful to catch the end of the session, so
you can shut down the connections.
--
Christopher St. John [EMAIL PROTECTED]
DistribuTopia http://www.distributopia.com
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