Class OortMasterService<R,C>

  • Type Parameters:
    R - the result type
    C - the opaque context type
    All Implemented Interfaces:
    java.util.EventListener, Bayeux.BayeuxListener, ConfigurableServerChannel.ServerChannelListener, ServerChannel.MessageListener, org.eclipse.jetty.util.component.LifeCycle
    Direct Known Subclasses:
    OortMasterLong

    public abstract class OortMasterService<R,C>
    extends OortService<R,C>

    OortMasterService extends OortService to allow applications to perform actions on entities that always live in a "master" node.

    Applications may have entities that are naturally owned by any node. For example, in a chat application a chat room may be created by a user in any node, and be owned by the node the user that created it is connected to.

    There are cases, however, where entities cannot be owned by any node, but instead must be owned by one node only, usually referred to as the "master" node.

    A typical example of such an entity is a unique (across the cluster) ID generator that produces IDs in the form of long - the primitive Java type - values, or a service that accesses a storage (such as a file system) that is only available on a particular node, etc.

    OortMasterService makes easier to write services that perform actions on entities that must be owned by a single node only. There is one instance of OortMasterService with the same name for each node, but only one of them is the "master". Then, applications may call getMasterOortURL() to get the Oort URL of the "master" node, and pass that Oort URL to OortService.forward(String, Object, Object) as described in OortService.

    • Constructor Detail

      • OortMasterService

        public OortMasterService​(Oort oort,
                                 java.lang.String name,
                                 boolean master)
        Parameters:
        oort - the oort this instance is associated to
        name - the name of this service
        master - whether this service lives on the "master" node
    • Method Detail

      • isMaster

        public boolean isMaster()
        Returns:
        whether this node is the "master" node
      • getMasterOortURL

        public java.lang.String getMasterOortURL()
        Returns:
        the "master" Oort URL, or null if the "master" node is down.
      • doStart

        protected void doStart()
                        throws java.lang.Exception
        Overrides:
        doStart in class OortService<R,C>
        Throws:
        java.lang.Exception
      • doStop

        protected void doStop()
                       throws java.lang.Exception
        Overrides:
        doStop in class OortService<R,C>
        Throws:
        java.lang.Exception