001 // Copyright 2004, 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; 016 017 import org.apache.tapestry.IEngine; 018 019 /** 020 * Service responsible for obtaining instances of {@link org.apache.tapestry.IEngine} 021 * to service the current request. An engine service may be retrieved from a pool, or extracted 022 * from the HttpSession. After the request is processed, the engine is re-stored into the 023 * HttpSession (if stateful) or back into the pool (if not stateful). 024 * 025 * @author Howard Lewis Ship 026 * @since 4.0 027 */ 028 public interface EngineManager 029 { 030 /** 031 * Locates or creates an engine instance for the current request. 032 */ 033 IEngine getEngineInstance(); 034 035 /** 036 * Store the engine back at the end of the current request. 037 */ 038 039 void storeEngineInstance(IEngine engine); 040 }