1 package org.apache.turbine.services;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 /**
23 * Interface for telling Turbine that the implementation class
24 * is an external service provider therefore can be used for looking
25 * up services not found by the Turbine implementation. It is
26 * assumed that the referenced service container handles the
27 * complete lifecycle of its services.
28 *
29 * @author <a href="mailto:siegfried.goeschl@it20one.at">Siegfried Goeschl</a>
30 */
31 public interface TurbineServiceProvider
32 {
33 /**
34 * Returns an instance of the requested service. If the
35 * given service is not available/found we throw a RuntimeException
36 * since this is less intrusive.
37 *
38 * @param roleName the name of the requested service
39 * @return an instance of the service
40 * @throws InstantiationException the service could not be instantiated
41 */
42 Object get(String roleName) throws InstantiationException;
43
44 /**
45 * Releases the instance you got before. This is only really
46 * required when not working with service singletons.
47 *
48 * @param component the component to release
49 */
50 void release(Object component);
51
52 /**
53 * Is the service known to the service container?
54 * @param roleName the name of the requested service
55 * @return true if the service is known to the provider
56 */
57 boolean exists(String roleName);
58 }