    001    package org.apache.turbine.services;
    002
    003    /*
    004     * Licensed to the Apache Software Foundation (ASF) under one
    005     * or more contributor license agreements.  See the NOTICE file
    006     * distributed with this work for additional information
    007     * regarding copyright ownership.  The ASF licenses this file
    008     * to you under the Apache License, Version 2.0 (the
    009     * "License"); you may not use this file except in compliance
    010     * with the License.  You may obtain a copy of the License at
    011     *
    012     *   http://www.apache.org/licenses/LICENSE-2.0
    013     *
    014     * Unless required by applicable law or agreed to in writing,
    015     * software distributed under the License is distributed on an
    016     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    017     * KIND, either express or implied.  See the License for the
    018     * specific language governing permissions and limitations
    019     * under the License.
    020     */
    021
    022    /**
    023     * Interface for telling Turbine that the implementation class
    024     * is an external service provider therefore can be used for looking
    025     * up services not found by the Turbine implementation. It is
    026     * assumed that the referenced service container handles the
    027     * complete lifecycle of its services.
    028     *
    029     * @author <a href="mailto:siegfried.goeschl@it20one.at">Siegfried Goeschl</a>
    030     */
    031    public interface TurbineServiceProvider
    032    {
    033        /**
    034         * Returns an instance of the requested service. If the
    035         * given servise is not available/found we throw a RuntimeException
    036         * since this is less intrusive.
    037         *
    038         * @param roleName the name of the requested service
    039         * @return an instance of the service
    040         * @throws InstantiationException the service could not be instantiated
    041         */
    042        public Object get(String roleName) throws InstantiationException;
    043
    044        /**
    045         * Releases the instance you got before. This is only really
    046         * required when not working with service singletons.
    047         *
    048         * @param component the component to release
    049         */
    050        public void release(Object component);
    051
    052        /**
    053         * Is the service known to the service container?
    054         */
    055        public boolean exists(String roleName);
    056    }