2 * Copyright (c) 2016 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.mdsal.singleton.common.api;
10 import org.opendaylight.yangtools.concepts.Registration;
13 * {@link ClusterSingletonServiceProvider} provides a functionality to register and group services
14 * {@link ClusterSingletonService} by service group identifier. Services could be Applications or RPCs.
15 * Provider provides a functionality which allows to have only one fully instantiated service instance
16 * in a cluster at one time and service group means to have all service instances for the same group
17 * situated on same Cluster Node. This is realized via a double candidate approach where a service
18 * group instance maintains a candidate registration for ownership of the service group entity in the
19 * cluster and also a registration that acts as a guard to ensure a service group instance has fully
20 * closed prior to relinquishing service group ownership. To achieve ownership of the service group,
21 * a service group candidate must hold ownership of both these entities.
23 public interface ClusterSingletonServiceProvider {
25 * Method registers {@link ClusterSingletonService} to Provider.
26 * Method returns {@link java.lang.RuntimeException} for unexpected state, so be careful with implementation.
27 * Note: RuntimeException is implemented as a notification about some problems with registration and client
28 * has to implement some strategy for handling this issue.
29 * TODO: RuntimeException is not a transparent contract for handling unexpected state and it needs to be
30 * replaced with a specific documented Exception or it needs to add another contract definition for a client
31 * notification about the unexpected state reason in {@link ClusterSingletonService}.
32 * RuntimeException implementation is a hotfix for an unwanted API contract changes in boron release only.
34 * @param service ClusterSingletonService instance
35 * @return {@link Registration} registration
37 Registration registerClusterSingletonService(ClusterSingletonService service);