Rename singleton service components

[mdsal.git] / singleton-service / mdsal-singleton-api / src / main / java / org / opendaylight / mdsal / singleton / api / ClusterSingletonServiceProvider.java

diff --git a/singleton-service/mdsal-singleton-api/src/main/java/org/opendaylight/mdsal/singleton/api/ClusterSingletonServiceProvider.java b/singleton-service/mdsal-singleton-api/src/main/java/org/opendaylight/mdsal/singleton/api/ClusterSingletonServiceProvider.java
new file mode 100644 (file)
index 0000000..3763c84
--- /dev/null
+++ b/singleton-service/mdsal-singleton-api/src/main/java/org/opendaylight/mdsal/singleton/api/ClusterSingletonServiceProvider.java
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2016 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.mdsal.singleton.api;
+
+import org.opendaylight.yangtools.concepts.Registration;
+
+/**
+ * {@link ClusterSingletonServiceProvider} provides a functionality to register and group services
+ * {@link ClusterSingletonService} by service group identifier. Services could be Applications or RPCs.
+ * Provider provides a functionality which allows to have only one fully instantiated service instance
+ * in a cluster at one time and service group means to have all service instances for the same group
+ * situated on same Cluster Node. This is realized via a double candidate approach where a service
+ * group instance maintains a candidate registration for ownership of the service group entity in the
+ * cluster and also a registration that acts as a guard to ensure a service group instance has fully
+ * closed prior to relinquishing service group ownership. To achieve ownership of the service group,
+ * a service group candidate must hold ownership of both these entities.
+ */
+public interface ClusterSingletonServiceProvider {
+    /**
+     * Method registers {@link ClusterSingletonService} to Provider.
+     * Method throws {@link RuntimeException} for unexpected state, so be careful with implementation.
+     * Note: RuntimeException is implemented as a notification about some problems with registration and client
+     * has to implement some strategy for handling this issue.
+     * TODO: RuntimeException is not a transparent contract for handling unexpected state and it needs to be
+     * replaced with a specific documented Exception or it needs to add another contract definition for a client
+     * notification about the unexpected state reason in {@link ClusterSingletonService}.
+     * RuntimeException implementation is a hotfix for an unwanted API contract changes in boron release only.
+     *
+     * @param service ClusterSingletonService instance
+     * @return {@link Registration} registration
+     */
+    Registration registerClusterSingletonService(ClusterSingletonService service);
+}