Donnerstag, Juli 01, 2004


EJB Lookup within Oracle Appliaction Server in usage of Clustering, Scalability and Fault-Tolerance

There is a main different between OC4J-Standalone EJB addressing schema and OC4J integrated in the Oracle Application Server. Think, Oracle Application Server has additional features regarding Clustering, Scalability and Fault-Tolerance, witch must be carefully attended in the deployment and EJB calling phase.
E.g. for scalability you can instance more then one OC4J components with the same configuration (many OC4J processes). In this case you must configure (default) a RMI port range in the opmn.xml. So OPMN (Oracle Process Monitor) is able to assign a different port to each OC4J instance in the startup phase.
A other feature of Oracle Application Server is to load balance the EJB calls depending of many different implemented algorithm (eg. round robin, metric based, ...). In each of this cases you can not address an OC4J instance directly like this:

env.put(Context.PROVIDER_URL, "ormi://HOST:PORT/EjbAppName")

In this situation you should us the following addressing schema:

env.put(Context.PROVIDER_URL, "opmn:ormi://HOST:OPMNPORT:OC4JInstanceName/EjbAppName");

Notice: for application portability, Oracle recommends to use instead of hardcoding the environment properties in client code.

You will find more information regarding OC4J and EJB in the OC4J Service Guide and in the OC4J-FAQ on OTN


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