BPEL Deployment on highly available SOA cluster server

What is highly available SOA cluster server?

Well this is the standard oracle recommended server configuration were you have say 2 application server, and a single RAC dehydration database.

You can find the details of this here.
http://download.oracle.com/docs/cd/E10291_01/core.1013/e10294/overview.htm

What is the default load balancer mechanism?

The default load balancer does a round robin request routing. Say if this is 2 AS instance, then first request goes to instance 1 and second request goes to instance 2.

Do you deploy on both servers?

Well this is a good question. As you got say atleast 2 Oc4J-SOA instances running.
Do I deploy to both the server or does the server take care when deployed to 1.

Well the answer is, the server takes care when you deploy to 1 server.
It automatically goes into the second server also.

How is load balancer related to deployment?

Well if look at the logs during deployment you would see that once you have some automated process to deploy.

The first process physically get deployed to server 1 and second process to server 2 and so on.

What about Polling processes running on both servers?

Well there are no issues with polling processes, it is taken care internally to do the right thing.
If one OC4J-SOA instance goes down the other picks in up automatically.

Server Configuration

Be sure to do server configuration on all the instaces as this does not get replicated at all.
You need to physically do this, that is logical.

Issue

With deployment plans there is a bug with cluster deployment.
The replacement happens only in the server where the process is deployed, the other servers still seem to get a copy of the non-replaced code.

This causes issues in deployment with 10.1.3.4 deployment plan.
This is a know bug and oracle has logged a bug to fix this.
A fix might be available soon.

Alternative for now is to while a shell script to do the find and replace for environment specific replacement. Once the fix from oracle is available, deployment plan should take care of the stuff for you.