001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.wicket.proxy; 018 019import org.apache.wicket.util.io.IClusterable; 020 021/** 022 * Represents a service locator for lazy init proxies. When the first method invocation occurs on 023 * the lazy init proxy this locator will be used to retrieve the proxy target object that will 024 * receive the method invocation. 025 * <p> 026 * Generally implementations should be small when serialized because the main purpose of lazy init 027 * proxies is to be stored in session when the wicket pages are serialized, and when deserialized to 028 * be able to lookup the dependency again. The smaller the implementation of IProxyTargetLocator the 029 * less the drain on session size. 030 * <p> 031 * A small implementation may use a static lookup to retrieve the target object. 032 * <p> 033 * Example: 034 * 035 * <pre> 036 * class UserServiceLocator implements IProxyTargetLocator 037 * { 038 * Object locateProxyObject() 039 * { 040 * MyApplication app = (MyApplication)Application.get(); 041 * return app.getUserService(); 042 * } 043 * } 044 * </pre> 045 * 046 * @see LazyInitProxyFactory#createProxy(Class, IProxyTargetLocator) 047 * 048 * @author Igor Vaynberg (ivaynberg) 049 * 050 */ 051public interface IProxyTargetLocator extends IClusterable 052{ 053 /** 054 * Returns the object that will be used as target object for a lazy init proxy. 055 * 056 * @return retrieved object 057 */ 058 <T> T locateProxyTarget(); 059}