001 // Copyright 2005 The Apache Software Foundation 002 // 003 // Licensed under the Apache License, Version 2.0 (the "License"); 004 // you may not use this file except in compliance with the License. 005 // You may obtain a copy of the License at 006 // 007 // http://www.apache.org/licenses/LICENSE-2.0 008 // 009 // Unless required by applicable law or agreed to in writing, software 010 // distributed under the License is distributed on an "AS IS" BASIS, 011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012 // See the License for the specific language governing permissions and 013 // limitations under the License. 014 015 package org.apache.tapestry.services.impl; 016 017 import java.io.IOException; 018 019 import org.apache.hivemind.util.Defense; 020 import org.apache.tapestry.IRequestCycle; 021 import org.apache.tapestry.engine.IEngineService; 022 import org.apache.tapestry.engine.ILink; 023 024 /** 025 * Outer proxy for engine services. The inner proxy resolves the engine service name to a engine 026 * service implementation and installed it into the outer proxy as a delegate. Although HiveMind 027 * does provide a similar system of inner and outer delegates, Tapestry's engine-service: 028 * {@link org.apache.tapestry.services.impl.EngineServiceObjectProvider} object provider can 029 * cause exceptions (recurive service build) when attempting to link two services together. This 030 * extra layer of proxying resolves that issue. 031 * 032 * @author Howard M. Lewis Ship 033 * @since 4.0 034 */ 035 public class EngineServiceOuterProxy implements IEngineService 036 { 037 private final String _serviceName; 038 039 private IEngineService _delegate; 040 041 public EngineServiceOuterProxy(String serviceName) 042 { 043 Defense.notNull(serviceName, "serviceName"); 044 045 _serviceName = serviceName; 046 } 047 048 void installDelegate(IEngineService delegate) 049 { 050 _delegate = delegate; 051 } 052 053 IEngineService getDelegate() 054 { 055 return _delegate; 056 } 057 058 public ILink getLink(IRequestCycle cycle, boolean post, Object parameter) 059 { 060 return _delegate.getLink(cycle, false, parameter); 061 } 062 063 public void service(IRequestCycle cycle) throws IOException 064 { 065 _delegate.service(cycle); 066 } 067 068 public String getName() 069 { 070 return _serviceName; 071 } 072 073 public String toString() 074 { 075 return ImplMessages.engineServiceOuterProxyToString(_serviceName); 076 } 077 078 }