Reg Distributed web applications and session migration

[Purna Chandra Rao]

Hi Ranchers,

In many of the mock exams i have found that its difficult for me figure out the options regarding session migration.
I will list down the points i know ..please tell me whether that is enough for the exam or i will have to prepare that topic more..or please add the points if i have missed out

1)We can make a web application distributed across multiple JVMs by configuring it in the DD as <distributable>true</distributable>
2)There will be one servletcontext per JVM,one servletconfig per servlet per JVM but there is only one session which is migrated from one JVM to other.
3)If the session attribute implements serializable then they are guarenteed to be transferred from one JVM to other,otherwise we need to do them explicitly by using HttpSessionActivationListener.

In one of the mock exams i have found something called default servletcontext..please help me what is it.

Thanks and Regards,
Purna Chandra Rao

[Khaled Mahmoud]

I have one thing to add which is :
The web container you are using must be configured to support
clustering.In case of the tomcat you can do this by editing
the server.xml inside the conf directory.

Regarding the third point which

otherwise we need to do them explicitly by using HttpSessionActivationListene

The Tomcat user guide at http://tomcat.apache.org/tomcat-5.0-doc/cluster-howto.html says the following

    
All your session attributes must implement java.io.Serializable

[Tridib Samanta]

1)We can make a web application distributed across multiple JVMs by configuring it in the DD as <distributable>true</distributable>

As distributable is an empty elemnt, I think it should be specified as <distributable/>

Pls correct me if I am wrong.
[ March 07, 2007: Message edited by: Tridib Samanta ]