001package org.apache.turbine.services;
002
003
004/*
005 * Licensed to the Apache Software Foundation (ASF) under one
006 * or more contributor license agreements.  See the NOTICE file
007 * distributed with this work for additional information
008 * regarding copyright ownership.  The ASF licenses this file
009 * to you under the Apache License, Version 2.0 (the
010 * "License"); you may not use this file except in compliance
011 * with the License.  You may obtain a copy of the License at
012 *
013 *   http://www.apache.org/licenses/LICENSE-2.0
014 *
015 * Unless required by applicable law or agreed to in writing,
016 * software distributed under the License is distributed on an
017 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
018 * KIND, either express or implied.  See the License for the
019 * specific language governing permissions and limitations
020 * under the License.
021 */
022
023
024import org.apache.commons.configuration2.Configuration;
025
026/**
027 * Classes that implement this interface can act as a broker for
028 * <code>Service</code> classes.
029 *
030 * Functionality that <code>ServiceBroker</code> provides in addition
031 * to <code>InitableBroker</code> functionality includes:
032 *
033 * <ul>
034 *
035 * <li>Maintaining service name to class name mapping, allowing
036 * plugable service implementations.</li>
037 *
038 * <li>Providing <code>Services</code> with <code>Properties</code>
039 * based on a system wide configuration mechanism.</li>
040 *
041 * </ul>
042 *
043 * @author <a href="mailto:burton@apache.org">Kevin Burton</a>
044 * @author <a href="mailto:krzewski@e-point.pl">Rafal Krzewski</a>
045 * @author <a href="mailto:dlr@collab.net">Daniel Rall</a>
046 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
047 * @version $Id$
048 */
049public interface ServiceBroker
050{
051    /**
052     * Determines whether a service is registered in the configured
053     * <code>TurbineResources.properties</code>.
054     *
055     * @param serviceName The name of the service whose existance to check.
056     * @return Registration predicate for the desired services.
057     */
058    boolean isRegistered(String serviceName);
059
060    /**
061     * Performs early initialization of the specified service.
062     *
063     * @param name The name of the service.
064     * @throws InitializationException if the service is unknown
065     * or can't be initialized.
066     */
067    void initService(String name) throws InitializationException;
068
069    /**
070     * Shutdowns a Service.
071     *
072     * This method is used to release resources allocated by a
073     * Service, and return it to initial (uninitailized) state.
074     *
075     * @param name The name of the Service to be uninitialized.
076     */
077    void shutdownService(String name);
078
079    /**
080     * Shutdowns all Services.
081     *
082     * This method is used to release resources allocated by
083     * Services, and return them to initial (uninitialized) state.
084     */
085    void shutdownServices();
086
087    /**
088     * Returns an instance of requested Service.
089     *
090     * @param name The name of the Service requested.
091     * @return An instance of requested Service.
092     * @throws InstantiationException if the service is unknown or
093     * can't be initialized.
094     */
095    Object getService(String name) throws InstantiationException;
096
097    /**
098     * Returns the configuration of a specific service. Services
099     * use this method to retrieve their configuration.
100     *
101     * @param name The name of the service.
102     * @return Configuration of the requested service.
103     */
104    Configuration getConfiguration(String name);
105
106    /**
107     * Get the application root as set by
108     * the parent application.
109     *
110     * @return String application root
111     */
112    String getApplicationRoot();
113}