Moving data around the place

The final listener is very useful as it lets an application know when Hazelcast is rebalancing the data within the cluster. This gives us an opportunity to prevent or even block the shutdown of a node, as we might be in a period of increased data resilience risk because we may be actively moving data around at the time. The interface used in this case is MigrationListener. It will notify the application when the partitions migrate from one node to another and when they complete:

public class ClusterMigrationListener implements MigrationListener {

  @Override
  public void migrationStarted(MigrationEvent migrationEvent) {
    System.err.println("Started: " + migrationEvent);
  }

  @Override
  public void migrationCompleted(MigrationEvent migrationEvent) {
    System.err.println("Completed: " + migrationEvent);
  }

  @Override
  public void migrationFailed(MigrationEvent migrationEvent) {
    System.err.println("Failed: " + migrationEvent);
  }
}

When you are...