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From Shailesh Potnis <>
Subject Re: Axis Clustering in OC4J Cluster
Date Fri, 08 Jan 2010 17:23:03 GMT
Hi Azeez:

Thank you for valuable input and links.  I think I went through the first link during my research
and the axis2.xml clustering guide includes info from the second link.  I am still not clear
about the end user use cases for stateless services.

What I am trying to determine is:  Under what specific scenarios Axis2 cluster deployed within
OC4J cluster would provide additional value,  In other words what would be use cases for using
Axis2 cluster within OC4J cluster that is fronted by OHS (Apache Web server) and a hardware
load balancer?  I am trying to find this only for stateless services.

During my discussion with some of my coworkers some possible use cases were discussed though
I do not know if they would be provided by Axis2 Cluster.  I would like to list them below:

1) In case a service is down in one Axis2 container, would Axis2 container redirect the request
to another container -- I think the you provided  (clustering at the servlet container level
(HTTP session & request replication) is out of the scope of Axis2) indicates that this
is not possible or out of scope. Correct me if this assumption is incorrect.
2) The second scenario is to be able to redeploy a single service (deployed with other services
in a single J2EE war) using a central remote  repository -- this may not be related to cluster
itself but would Axis clustering assist accomplishing this when OC4J standard deployment requires
entire Axis2 war (potentially containing multiple services) to be redeployed.  Would like
to know whether this can be done using a central repository and Axis2 Admin console (with
or without Axis2 cluster).
3) What are specific advantages of replicating ConfigurationContext, ServiceGroupContext &
ServiceContext (For someone who has limited understanding of those objects) in Axis2 cluster
for stateless services?

 Thank You and Best Regards



From: AfkhamAzeez <>
Sent: Fri, January 8, 2010 12:30:00 AM
Subject: Re: Axis Clustering in OC4J Cluster

We have not tested Axis2 clustering on OC4J AFAIK.
With respect to state replication, at the Axis2 level, we are only
concerned about replicating the values stored in the Axis2
ConfigurationContext, ServiceGroupContext & ServiceContext. We use
default Java serialization, hence the entire object tree should be
serializable for the replication to be successful. Please note that
clustering at the servlet container level (HTTP session & request
replication) is out of the scope of Axis2 and has to be handled by the
respective servlet containers.

For more details; refer to my articles;
1. Introduction to WSO2 Carbon Clustering
2. WSO2 Carbon Cluster Configuration Language


On Fri, Jan 8, 2010 at 1:29 AM, Shailesh Potnis <> wrote:
> Hi:
> I am going through a good deal of Axis2 documents and links.  I am trying to determine
if anyone has deployed Axis2 Cluster within OC4J cluster and what is the experience.  I am
planning to use it exclusively for stateless web services.  Here are some specific questions:
> 1) What would be specific benefits of deploying the stateless web services in Axis2 cluster
when scalability would be provided by OC4J cluster?
> 2) Are the Axis2 clustering benefits limited to deploying in Tomcat or are useful in
other app servers?
> 3) In case a service is hung due to application or infrastructure issues, would Axis2
cluster direct a request to another Axis2 instance in a cluster?
> I posted the above some time ago in the Axis2 developers group and I think that this
group may be a more appropriate group for this.
> Also when I deployed a stateless service (with a single stateless operation: version),
I get the following error:
> Could not send command message ContextClusteringCommandCollection to group since it is
not serializable
> I will be glad to send complete stack trace if necessary.
> All helpful suggestions are highly appreciated..
> Thank You and Best Regards
> Sincerely
> Shailesh


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