Configuring EJB 3.0 and EJB 2.1 Stateful Session Bean Replication Policy

The general procedure for configuring EJB application clustering for an EJB 3.0 or EJB 2.1 stateful session bean is:

Configure your OC4J application cluster (see "Application Clustering in OC4J" in the Oracle Containers for J2EE Configuration and Administration Guide).
Configure a replication policy for stateful session beans on each node (see "Using Deployment XML"):
Deploy your EJB to any one of the nodes in the cluster.

For more information, see "State Replication".

Using Deployment XML

To configure a replication policy, add a <replication-policy> element to one or more of the appropriate deployment descriptor files that Table 24-1 lists.

You can specify a single replication policy that OC4J applies globally or specify finer-grained replication policy at the application level for both Web and EJB components or EJB components only.

Configure the trigger attribute to one of the following:

onRequestEnd — replicate at the end of each EJB method call
onShutdown — replicate when the JVM is terminating normally

The scope attribute is always set to allAttributes for a stateful session bean.

For more information, see "State Replication Trigger".

Table 24-1 Deployment XML Files for Replication Policy Configuration

Scope	Affected Components	Deployment XML File	See also ...
Global	Web and EJB	`application.xml`	"Configuring Global Replication Policy in the application.xml File for Web and EJB Components"
Application-level	Web and EJB	`orion-application.xml`	"Configuring Application-Level Replication Policy in the orion-application.xml File for Web and EJB Components"
Application-level	EJB	`orion-ejb-jar.xml`	"Overriding Application-Level Replication Policy in the orion-ejb-jar.xml File for EJB Components"

Configuring Global Replication Policy in the application.xml File for Web and EJB Components

When you configure the application.xml file with a state replication policy (see Example 24-1), it applies to all Web components and to all stateless session beans deployed to this instance of OC4J.

Example 24-1 The application.xml For a Global Replication Policy

<application>
...
    <replication-policy
        trigger="onRequestEnd"        scope="allAttributes"
    />
...
</application>

Configuring Application-Level Replication Policy in the orion-application.xml File for Web and EJB Components

When you configure the orion-application.xml file with a state replication policy (see Example 24-2), it applies to all Web components and to all stateless session beans deployed to this instance of OC4J.

Example 24-2 The orion-application.xml For an Application-Level Replication Policy

<orion-application>
...
    <replication-policy
        trigger="onShutdown"        scope="allAttributes"
    />
...
</orion-application>

Overriding Application-Level Replication Policy in the orion-ejb-jar.xml File for EJB Components

When you configure the orion-ejb-jar.xml file with a state replication policy for a stateful session bean (see Example 24-3), each bean can use a different type of replication independent of the Web component replication type.

Example 24-3 The orion-ejb-jar.xml For an Application-Level Replication Policy for EJBs

<orion-ejb-jar>
...
    <session-deployment
        name="AirlinePOEndpointBean"
        max-tx-retries="0"
        location="AirlinePOEndpointBean"
        persistence-filename="AirlinePOEndpointBean">
...
        <replication-policy
            trigger="onRequestEnd"            scope="allAttributes"
        />
...
    </session-deployment>
...
</orion-ejb-jar>