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Administration Console Online Help

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Configure a singleton service

Before you begin

Ensure that you have defined a singleton service using the Administration Console. See Define a new singleton service.


A singleton service is a service running on a Managed Server that is available on only one member of a cluster at a time. WebLogic Server allows you to automatically monitor and migrate singleton services from one server instance to another.

To configure the migration behavior of a singleton service:

  1. If you have not already done so, in the Change Center of the Administration Console, click Lock & Edit (see Use the Change Center).
  2. In the left pane of the Console, select Environment > Clusters.

    The Summary of Clusters table displays all the clusters defined in the domain.
  3. In the Clusters table, select the cluster containing the singleton service you want to configure.
  4. Select Configuration > Singleton Services.
  5. In the Singleton Services table, select the singleton service you want to configure.
  6. Select Configuration > General.
    1. In Class Name, define the fully qualified name to the class. The class must also be contained in the server classpath.

      The class specified in Class Name must implement the singleton service interface in order to function as a migratable singleton service. See Service-Level Migration.

    2. In Additional Migration Attempts, enter the number of further attempts that should be tried to reach a migratable service after the service has failed on every possible configured server instance at least once.
    3. In Sleep Time Between Attempts, enter the length of the pause between migration attempts.
  7. Select Configuration > Migration.
    1. In User Preferred Server, select the preferred server instance for this singleton service.
    2. In Constrained Candidate Servers, select server instances in the cluster to use as a backup for services on this singleton service. Move server instances from Available to Chosen using the arrows.
  8. Click Save.
  9. To activate these changes, in the Change Center of the Administration Console, click Activate Changes.
    Not all changes take effect immediately—some require a restart (see Use the Change Center).

After you finish

The singleton service created using these procedures uses the default behavior for determining the list of candidate servers for migration. The default is to iterate through all of the servers in the cluster. To configure the list of candidate servers and other aspects of automatic server migration, see Configure server migration in a cluster.


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