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    package org.apache.oozie.service;
019    
020    /**
021     * A service is component managed by the {@link Services} singleton.
022     */
023    public 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    }