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    import java.io.Serializable;
019    
020    import org.apache.hivemind.util.Defense;
021    import org.apache.tapestry.IRequestCycle;
022    import org.apache.tapestry.engine.IEngineService;
023    import org.apache.tapestry.engine.ILink;
024    
025    /**
026     * Outer proxy for engine services. The inner proxy resolves the engine service name to a engine
027     * service implementation and installed it into the outer proxy as a delegate. Although HiveMind
028     * does provide a similar system of inner and outer delegates, Tapestry's engine-service:
029     * {@link org.apache.tapestry.services.impl.EngineServiceObjectProvider} object provider can
030     * cause exceptions (recurive service build) when attempting to link two services together. This
031     * extra layer of proxying resolves that issue.
032     * 
033     * @author Howard M. Lewis Ship
034     * @since 4.0
035     */
036    public class EngineServiceOuterProxy implements IEngineService, Serializable
037    {
038        
039        /**
040         * generated.
041         */
042        private static final long serialVersionUID = 2050789495671401625L;
043    
044        private final String _serviceName;
045    
046        private IEngineService _delegate;
047    
048        public EngineServiceOuterProxy(String serviceName)
049        {
050            Defense.notNull(serviceName, "serviceName");
051    
052            _serviceName = serviceName;
053        }
054    
055        void installDelegate(IEngineService delegate)
056        {
057            _delegate = delegate;
058        }
059    
060        IEngineService getDelegate()
061        {
062            return _delegate;
063        }
064    
065        public ILink getLink(boolean post, Object parameter)
066        {
067            return _delegate.getLink(post, parameter);
068        }
069    
070        public void service(IRequestCycle cycle) throws IOException
071        {
072            _delegate.service(cycle);
073        }
074    
075        public String getName()
076        {
077            return _serviceName;
078        }
079    
080        public String toString()
081        {
082            return ImplMessages.engineServiceOuterProxyToString(_serviceName);
083        }
084    
085    }