001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *      http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.oozie.service;
020
021/**
022 * A service is component managed by the {@link Services} singleton.
023 */
024public interface Service {
025    String DEFAULT_LOCK_TIMEOUT = "oozie.service.default.lock.timeout";
026
027    /**
028     * Prefix for all services configuration properties.
029     */
030    String CONF_PREFIX = "oozie.service.";
031
032    /**
033     * Initialize the service. <p> Invoked by the {@link Service} singleton at start up time.
034     *
035     * @param services services singleton initializing the service.
036     * @throws ServiceException thrown if the service could not initialize.
037     */
038    void init(Services services) throws ServiceException;
039
040    /**
041     * Destroy the service. <p> Invoked by the {@link Service} singleton at shutdown time.
042     */
043    void destroy();
044
045    /**
046     * Return the public interface of the service. <p> Services are retrieved by its public interface. Specializations
047     * of services must return the public interface.
048     *
049     * @return the interface of the service.
050     */
051    Class<? extends Service> getInterface();
052
053    /**
054     * Lock timeout value if service is only allowed to have one single running instance.
055     */
056    long lockTimeout = ConfigurationService.getLong(DEFAULT_LOCK_TIMEOUT);
057
058}