Wednesday, 8 April 2009

New Wait option for Sequential Redeployment in a clustered OAS setup

When you have an application using HTTP session replication setup in a HA cluster on OAS and above you can easily ensure that when you deploy a new version of that application it will continue to run with no down time. What's important here is you select the correct deployment option.

Redeploying with ASC

If you use ASC for the deployment then your effectively redeploying to the cluster in parallel - all nodes in cluster will get notified and process the deployment in parallel. That means you will most likey have down time and get errors for those currently using your application.

Redeploy with admin_client.jar or redeploy Ant task

With these two deployment choices you can specify sequential and keepsettings options however in some circumstances the session state of an application may be lost when you redeploy an application to a cluster.

In Oracle Containers for J2EE release or, you can use either the waitsec parameter of the admin_client.jar -sequential waitsec subswitch or the sequentialDelay property of the redeploy Ant task to specify a number of seconds between redeployments to different OC4J instances in a cluster. This delay can provide enough time for replication of session state

For example, the following admin_client.jar command specifies a wait time of 15 seconds between redeployments to different OC4J instances:

java -jar admin_client.jar deployer:cluster:opmn://host:port/home oc4jadmin
password -redeploy -file "myapp.ear" -deploymentName rolling -sequential 15
It's documented here, make sure your using or above for this
10.1.14 New Wait Option for Sequential Redeployment to a Cluster

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