001package org.apache.turbine.pipeline; 002 003 004/* 005 * Licensed to the Apache Software Foundation (ASF) under one 006 * or more contributor license agreements. See the NOTICE file 007 * distributed with this work for additional information 008 * regarding copyright ownership. The ASF licenses this file 009 * to you under the Apache License, Version 2.0 (the 010 * "License"); you may not use this file except in compliance 011 * with the License. You may obtain a copy of the License at 012 * 013 * http://www.apache.org/licenses/LICENSE-2.0 014 * 015 * Unless required by applicable law or agreed to in writing, 016 * software distributed under the License is distributed on an 017 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 018 * KIND, either express or implied. See the License for the 019 * specific language governing permissions and limitations 020 * under the License. 021 */ 022 023 024import java.io.IOException; 025 026import org.apache.turbine.util.TurbineException; 027 028/** 029 * The idea of a pipeline is being taken from Catalina 030 * in its entirety :-) 031 * 032 * I would like to take the idea further and implement 033 * Valves instead of hardcoding particular methods 034 * in a pipeline. 035 * 036 * It would be more flexible to specify Valves for 037 * a pipeline in an XML file (we can also rip off the 038 * digester rules from T4) and have invoke() as part 039 * of the interface. 040 * 041 * So a set of Valves would be added to the pipeline 042 * and the pipeline would 'invoke' each valve. In the 043 * case Turbine each Valve would produce some output 044 * to be sent out the pipe. I think with another days 045 * work this can be fully working. The first pipeline 046 * to be fully implemented will the ClassicPipeline 047 * will emulate the Turbine 2.1 way of doing things. 048 * 049 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a> 050 * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a> 051 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a> 052 */ 053public interface Pipeline 054{ 055 /** 056 * Initializes this instance. Called once by the Turbine servlet. 057 * @throws Exception if the initialization fails 058 */ 059 void initialize() 060 throws Exception; 061 062 /** 063 * <p>Add a new Valve to the end of the pipeline.</p> 064 * 065 * @param valve Valve to be added. 066 * 067 * @throws IllegalStateException If the pipeline has not been 068 * initialized. 069 */ 070 void addValve(Valve valve); 071 072 /** 073 * Return the set of all Valves in the pipeline. If there are no 074 * such Valves, a zero-length array is returned. 075 * 076 * @return An array of valves. 077 */ 078 Valve[] getValves(); 079 080 /** 081 * <p>Cause the specified request and response to be processed by 082 * the sequence of Valves associated with this pipeline, until one 083 * of these Valves decides to end the processing.</p> 084 * 085 * <p>The implementation must ensure that multiple simultaneous 086 * requests (on different threads) can be processed through the 087 * same Pipeline without interfering with each other's control 088 * flow.</p> 089 * 090 * @param pipelineData The run-time information, including the servlet 091 * request and response we are processing. 092 * @throws TurbineException if the invocation fails 093 * @throws IOException an input/output error occurred. 094 */ 095 void invoke(PipelineData pipelineData) 096 throws TurbineException, IOException; 097 098 /** 099 * Remove the specified Valve from the pipeline, if it is found; 100 * otherwise, do nothing. 101 * 102 * @param valve Valve to be removed. 103 */ 104 void removeValve(Valve valve); 105}