OIM11G Cluster Installation Post Configuration for SOA

When running the IDM configuration wizard we are required to enter the load balancer URL but load balancer is not required for clustered installation. Thus URL for oim_server1 can be entered in the wizard and configuration be completed.
Now if in the clustered installation there are two oim severs (oim_server1, oim_server2 [oim_cluster]) and two soa servers (soa_server1, soa_server2 [soa_cluster]), there would be issues in approval flows if
oim_sever1 is shutdown (leaving oim_server2 and both the soa server running). The approvals would fail and in the BPEL fault we will see that the Approval Callback is trying to send the response back to oim_server1 rather then oim_server2. If we start back oim_server1 than the approvals along with call backs work fine.
Another scenarios which can be tried is to shut down oim_server2 instead of oim_server1 & than the approvals would works fine.

With the above test we can see that configuration is pointing the oim server to oim_server1 host rather than a cluster. So how to configure the domain post installation so that SOA would point to both the oim servers and would automatic failover? This can be done by changing the oimFrontEndUrl  in the oim-config.xml. This value can be changed to point to any proxy server (say OHS, Apache) and use the mod so plugin at the proxy and redirect requests from proxy to OIM cluster.

OIM11G Cluster Configuration

While doing clustered installation of OIM and SOA there is no way to define which component (SOA, OIM) is installed on the defined managed server at the time of installation. The document syas that when you first enter the configure managed servers screen, two managed servers called oim_server1 and soa_server1 are created automatically. Rename soa_server1 to WLS_SOA1 and oim_server1 to WLS_OIM1 and update their attributes as required for host/port and  then, add two new managed servers called WLS_OIM2 and WLS_SOA2 .Thus if four servers (Two OIM and two SOA) are defined in the domain then there is not way to know which servers are going to target the OIM application(s) and it's librarie(s) and which server is going to have the SOA application(s) and librarie(s). It surely does not work based on name like if server name contains OIM then that server is going to target OIM binaries and what happens if I want my servers to be named as instance1, instance2, instance3 and so on ....

The above problem can be solved by adding the servers in the domain creation wizard in a specified order or sequence. In the configure managed servers screen, the first server and each odd server entered is always the OIM server and the second server and each even server is the SOA server.