7 Migration and Recovery for Clustered MDBs

WebLogic Server supports migration and recovery for clustered MDB applications. In the event of failure, you can bring a JMS destination and MDBs back online. Design your application so that when a server instance fails, your application automatically migrates the JMS destination and its associated MDBs from the failed server in the cluster to an available server instance.

Note:

An MDB can use the migratable service with clustered servers only. The migratable service cannot span multiple clusters.

After an MDB application migrates to another server, it reconnects to the migrated JMS destination and begins to receive messages from the JMS destination again.

MDBs do not have migratable targets. Instead, an MDB automatically detects the JMS Server migration target during deployment, and uses that as its migratable target. You must ensure that MDB are deployed everywhere that a JMS Server is deployed. You can do this in two ways:

• Deploy MDBs homogeneously to the cluster.

• Match an MDB's targets to the JMS migratable target list in the config.xml file for the server instance's cluster. The MDB target server name must match the JMS migratable target list, or MDB migration will fail. For more information on configuring migratable targets, see "Understanding Migratable Target Servers in a Cluster" in Oracle Fusion Middleware Using Clusters for Oracle WebLogic Server.

In Figure 7-1, Managed Servers 1, 2 and 3 are in the same cluster. Managed Server 2 and Managed Server 3 are configured as Managed Server 1's migratable targets. In the event that Managed Server 1 fails, the JMS destination and MDB migrate to the next available Managed Server. If a Managed Server on the target list is unavailable, the destination and MDBs migrate to the next available Managed Server on the target list. For instance if Managed Server 2 is unavailable with Managed Server 1 fails, the JMS destination and MDB application migrate to Managed Server 3.

Figure 7-1 Migration of JMS Destination

Description of "Figure 7-1 Migration of JMS Destination"

For instructions on implementing the migratable service and for background information on WebLogic JMS migration and recovery services for clustered architectures, see "JMS as a Migratable Service within a Cluster" in Oracle Fusion Middleware Configuring and Managing JMS for Oracle WebLogic Server.