10 Replies Latest reply on Mar 7, 2008 1:43 PM by Sebastián Lacuesta

    Another way to write clustered singletons

    Dimitris Andreadis Master

      Just added notifications emitted by the HASingletonDeployer:
      http://jira.jboss.com/jira/browse/JBAS-2626
      and a BarrierController http://wiki.jboss.org/wiki/Wiki.jsp?page=BarrierController listening to them to control a Barrier.

      So services deployed normally inside ./deploy or ./farm that want to be
      started/stopped whenever the content of ./deploy-hasingleton/ gets
      deployed/undeployed, or else, whenever the current node becomes the
      master, need only specify a dependency on the Barrier mbean:

      <depend>jboss.ha:service=HASingletonDeployer,type=Barrier</depend>
      


      This provides an alternative to the deploy-hasingleton approach in that we can use farming to distribute the service, while content in deploy-hasingleton must be copied manually on all nodes. On the other hand, the farmed service will be instantiated/created on all nodes, but only started on the master node.

      So this is not a replacement, rather one more option for writing clusterred singleton services.