Oracle Process Manager & Notification Server (OPMN) is a new addition to R12 E-Business Suite Technology Stack.

OPMN manages all Oracle Application Server 10g Components (like 1. Oracle HTTP Server, 2. OC4J etc).

OPMN has three components.

COMPONENT	DESCRIPTION
Oracle Notification Server	Tool which carries messages (about failure, recovery, start) between different components of Oracle Application server
Oracle Process Manager	Central process management tool which manages all components of Application Server 10g It is responsible for start, stop, monitor, failure detection, automatic restart of the processes it manages
Process Manager	Tool which communicates the messages originating from the running component, holds the control information on how to start, stop etc.

OPMN can be intergrated with Oracle Enterprise Manager 10g Application Server Control Console. AS Control Console is the graphical user interface and can manage all Oracle Application Server components, under single view.

So... What it does, for Oracle Apps tech Stack?

As OPMN can explicitly manage Oracle HTTP Server and OC4J, it can as well detect if they are down or unanswering.

Say for example, there are several nodes of Oracle E-Business Suite R12 middle tier, on clustering (load balancing on Oracle HTTP Server). OPMN can monitor all the processes by pinging them, So when they are down, OPMN can automatically restart them.

Now, what is Replication of Session state:

Some Applications wants Oracle Applications Server 10g (in its middle tier) to maintain the stateful information to serve all consecutive requests. When such application is deployed on clustering, it is necessary to maintain the session state across multiple processes, in order to provide transparent failover of the requests.

Multiple redundant process would be made available, so that any processes can serve the client request. In the event of failure of one process, the another process can serve the same request successfully.

So... Does Oracle E-Business Suite R12 support state replication?

Oracle Applications Server supports state replication using Application-level clustering, for J2EE application.

Oracle HTTP listener routes the requests to the redundant OC4J Components , hence ensuring the state is replicated.

Oracle AS Web Cache 10g provides stateless and stateful load balancing. Multiple instances of Oracle AS web Cache configures to be a Web Cache Clustering, these provide failover clustering in case one of the WebCache member fails.

Thus, with E-Business Suite R12, Session State Replication (of the requests) is possible both for HTML based interface (OA framework Pages) and Professional user interface (Forms based).