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 */
018package org.apache.oozie.service;
019
020/**
021 * A service is component managed by the {@link Services} singleton.
022 */
023public interface Service {
024    public static final String DEFAULT_LOCK_TIMEOUT = "oozie.service.default.lock.timeout";
025
026    /**
027     * Prefix for all services configuration properties.
028     */
029    public static final String CONF_PREFIX = "oozie.service.";
030
031    /**
032     * Constant for XCommand
033     */
034    public static final String USE_XCOMMAND = "oozie.useXCommand";
035
036    /**
037     * Initialize the service. <p/> Invoked by the {@link Service} singleton at start up time.
038     *
039     * @param services services singleton initializing the service.
040     * @throws ServiceException thrown if the service could not initialize.
041     */
042    public void init(Services services) throws ServiceException;
043
044    /**
045     * Destroy the service. <p/> Invoked by the {@link Service} singleton at shutdown time.
046     */
047    public void destroy();
048
049    /**
050     * Return the public interface of the service. <p/> Services are retrieved by its public interface. Specializations
051     * of services must return the public interface.
052     *
053     * @return the interface of the service.
054     */
055    public Class<? extends Service> getInterface();
056
057    /**
058     * Lock timeout value if service is only allowed to have one single running instance.
059     */
060    public static long lockTimeout = Services.get().getConf().getLong(DEFAULT_LOCK_TIMEOUT, 5 * 1000);
061
062}