why is session clustered when load balancing or failover is

[mermaid]

All the docs relating to clustering web application mention that when the application is deployed in the -all folder, session state is replicated but load balancing or failover is not taken care by jboss.An external software or hardware loadbalancer has to be used
Then what is the use of providing only session replication feature? How can we test only session rep feature without loadbalancing and failover?

Thanks

[brian.stansberry]

http://wiki.jboss.org/wiki/Wiki.jsp?page=UsingMod_jk1.2WithJBoss

[mermaid]

Thanks for the reply...
I have been through this link.
But my query is still unanswered
Session replication will happen when my web app is placed inside the all/deploy folder, but no load balance or failover is provided (we have to use an external loadbalancer for this).
Is there any specific reason why only session replication is provided in the -all config?
So the conclusion I draw is only session replication cannot be tested, always an external loadbalancer has to be used.

[brian.stansberry]

The JBoss AS src dist used to include a webapp that could be deployed that would function as a load balancer. It was never intended to be used in any kind of production setting; could only be used for testing. Hence it was never included in the 'all' config; it had to be built from the src dist and deployed. It was completely unmaintained and untested and AFAICT rarely used. For roughly the same effort as building and installing this webapp, you could download and install Apache and mod_jk, and as a bonus get an understanding of how to use a production quality load balancer. Because of all this, we decided to drop the load balancer webapp from the JBoss src.

[brian.stansberry]

Note that you should be able to test session replication with 2 JBoss instances on one box if you use the ServiceBindingManager to ensure both processes use different ports. See http://wiki.jboss.org/wiki/Wiki.jsp?page=ReplicatedCounter . Key point is the hostname portion of the URL must be the same for both AS instances. Otherwise, the browser will not present the session cookie to the second AS instance when you test failover.

[mermaid]

Thanks for the reply.....
It helped .....

[brian.stansberry]

One last bit -- if you're talking about automated testing, you can use a library like Apache HttpClient and programatically switch the client and session cookie from one server to the other to test failover. In that case you don't need to use ServiceBindingManager; you can start your AS instances on separate machines or on the same machine but bound to different IP addresses. To see how to do this, have a look at the session replication unit tests in the org.jboss.test.cluster package in the AS src dist testsuite module.