Hi,
Let say there is a webapp called mywebapp on a two member tomcat cluster. Let's call the
members tomcatA and tomcatB. The Developer wants to deploy a new version of mywebapp. The
following procedure was thought:
- Shut down one of the tomcats. Let it be tomcatA. From here on the existing sessions will
be served from tomcatB till further notice.
- Replace the clustered server.xml on tomcatA with a non-clustered server.xml
- Bring up tomcatA. At this moment tomcatA is not participating in the cluster, any session
with the URL: http://hostA:8080/mywebapp should have a standalone session id with no indication
any of the two tomcat instances.
- Undeploy mywebapp.
- Deploy the new mywebapp on tomcatA with the olld name, that is as mywebapp.
- Shut down tomcatA
- Replace the non-clustered server.xml with the clustered server.xml
- Startup tomcatA
Here is the point where I need guidance.
- Does the tomcat cluster know that mywebapp on tomcatA is different from mywebapp still
running on tomcatB ? If yes, how does it know it ? Will at this point the sessions from
tomcatB replicated to tomcatA ?
- If I want my new mywebabb to clusterized should I deploy it also on tomcatB ? If yes -
because somehow the cluster knows that although the name and the context path is the same,
the apps are in reality different -, then how,t do so and at the same time preserve the existing
sessions in tomcatB, that is replicating them over to tomcatA.
My test shows, that if I just start up tomcatA with the new mywebapp on it as soon as I shut
down tomcatB the sessions over tomcatB are lost. I would like to preserve those sessions
and bring them over to tomcatA, so I can do the same procedure on tomcatB that I did on tomcatA,
that is replacing the old app with the new one.
So I am interested how others are doing it without loosing any sessions and without restrictions
t the users.
Thanks ahead,
János
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