+/*
+ * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.controller.remote.rpc.registry.gossip;
+
+import akka.actor.ActorRef;
+import java.util.Optional;
+
+/**
+ * Marker interface for data which is able to be held in a {@link Bucket}.
+ *
+ * @author Robert Varga
+ *
+ * @param <T> Concrete BucketData type
+ */
+public interface BucketData<T extends BucketData<T>> extends Copier<T> {
+ /**
+ * Return the {@link ActorRef} which should be tracked as the authoritative source of this bucket's data.
+ * The bucket will be invalidated should the actor be reported as Terminated.
+ *
+ * @return Optional ActorRef.
+ */
+ Optional<ActorRef> getWatchActor();
+}