1 package org.apache.turbine.pipeline; 2 3 4 /* 5 * Licensed to the Apache Software Foundation (ASF) under one 6 * or more contributor license agreements. See the NOTICE file 7 * distributed with this work for additional information 8 * regarding copyright ownership. The ASF licenses this file 9 * to you under the Apache License, Version 2.0 (the 10 * "License"); you may not use this file except in compliance 11 * with the License. You may obtain a copy of the License at 12 * 13 * http://www.apache.org/licenses/LICENSE-2.0 14 * 15 * Unless required by applicable law or agreed to in writing, 16 * software distributed under the License is distributed on an 17 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 18 * KIND, either express or implied. See the License for the 19 * specific language governing permissions and limitations 20 * under the License. 21 */ 22 23 24 import java.io.IOException; 25 26 import org.apache.turbine.util.TurbineException; 27 28 /** 29 * The idea of a pipeline is being taken from Catalina 30 * in its entirety :-) 31 * 32 * I would like to take the idea further and implement 33 * Valves instead of hardcoding particular methods 34 * in a pipeline. 35 * 36 * It would be more flexible to specify Valves for 37 * a pipeline in an XML file (we can also rip off the 38 * digester rules from T4) and have invoke() as part 39 * of the interface. 40 * 41 * So a set of Valves would be added to the pipeline 42 * and the pipeline would 'invoke' each valve. In the 43 * case Turbine each Valve would produce some output 44 * to be sent out the pipe. I think with another days 45 * work this can be fully working. The first pipeline 46 * to be fully implemented will the ClassicPipeline 47 * will emulate the Turbine 2.1 way of doing things. 48 * 49 * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a> 50 * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a> 51 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a> 52 */ 53 public interface Pipeline 54 { 55 /** 56 * Initializes this instance. Called once by the Turbine servlet. 57 */ 58 public void initialize() 59 throws Exception; 60 61 /** 62 * <p>Add a new Valve to the end of the pipeline.</p> 63 * 64 * @param valve Valve to be added. 65 * 66 * @exception IllegalStateException If the pipeline has not been 67 * initialized. 68 */ 69 public void addValve(Valve valve); 70 71 /** 72 * Return the set of all Valves in the pipeline. If there are no 73 * such Valves, a zero-length array is returned. 74 * 75 * @return An array of valves. 76 */ 77 public Valve[] getValves(); 78 79 /** 80 * <p>Cause the specified request and response to be processed by 81 * the sequence of Valves associated with this pipeline, until one 82 * of these Valves decides to end the processing.</p> 83 * 84 * <p>The implementation must ensure that multiple simultaneous 85 * requests (on different threads) can be processed through the 86 * same Pipeline without interfering with each other's control 87 * flow.</p> 88 * 89 * @param data The run-time information, including the servlet 90 * request and response we are processing. 91 * 92 * @exception IOException an input/output error occurred. 93 */ 94 public void invoke(PipelineData data) 95 throws TurbineException, IOException; 96 97 /** 98 * Remove the specified Valve from the pipeline, if it is found; 99 * otherwise, do nothing. 100 * 101 * @param valve Valve to be removed. 102 */ 103 public void removeValve(Valve valve); 104 }