clustering

[John Coleman <jo...@eurobase-international.com>]

Hi,

 

We have a thin web application that basically just manages the front end
for a remote business layer that handles the heavy session state stuff
and persistence. Basically the webapp emits and receives data as XML and
after some processing makes it available to the clients.

 

We want to cluster Tomcat in order to support more users, but I expect
each Tomcat instance will be able to manage 500+ sessions, whereas each
of our web applications can only have 250 sessions with the remote
business layer.

 

Is there a way for a single Tomcat instance to run 2 copies of the
application, each one pointing to its own instance of the business
layer? It seems silly to run 2 Tomcats, one for each application
instance, as I suspect that will waste memory and processor. I expect I
will just have to deploy the application twice to 2 different contexts,
but how is that dealt with when configuring load balancing and
clustering, or can I just use different port numbers?

 

Also, can I set a limit of 250 sessions in tomcat for a given
application so we don't blow out on the remote system?

 

John


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RE: clustering

["Caldarale, Charles R" <Ch...@unisys.com>]

> From: John Coleman [mailto:john.coleman@eurobase-international.com] 
> Subject: clustering
> 
> I expect I will just have to deploy the application 
> twice to 2 different contexts, but how is that dealt
> with when configuring load balancing and clustering,
> or can I just use different port numbers?

Yes, you can use two different contexts, rather than running multiple
Tomcats.  Each must have a unique name, of course.  You could write a
simple filter or valve that tracks current usage and forwards requests
to the less busy context.

> Also, can I set a limit of 250 sessions in tomcat for a given
> application so we don't blow out on the remote system?

Not with any standard configuration parameters that I'm aware of.
Again, a fairly simple filter could be used to track and limit the
number of concurrent sessions for a given context.

 - Chuck


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