001 package 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
024 import java.io.IOException;
025
026 import org.apache.turbine.util.TurbineException;
027
028 /**
029 * <p>A <b>ValveContext</b> is the mechanism by which a Valve can trigger the
030 * execution of the next Valve in a Pipeline, without having to know anything
031 * about the internal implementation mechanisms. An instance of a class
032 * implementing this interface is passed as a parameter to the
033 * <code>Valve.invoke()</code> method of each executed Valve.</p>
034 *
035 * <p><strong>IMPLEMENTATION NOTE</strong>: It is up to the implementation of
036 * ValveContext to ensure that simultaneous requests being processed (by
037 * separate threads) through the same Pipeline do not interfere with each
038 * other's flow of control.</p>
039 *
040 * @author Craig R. McClanahan
041 * @author Gunnar Rjnning
042 * @author Peter Donald
043 * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
044 * @version $Revision: 615328 $ $Date: 2008-01-25 21:25:05 +0100 (Fr, 25 Jan 2008) $
045 */
046 public interface ValveContext
047 {
048 /**
049 * <p>Cause the <code>invoke()</code> method of the next Valve
050 * that is part of the Pipeline currently being processed (if any)
051 * to be executed, passing on the specified request and response
052 * objects plus this <code>ValveContext</code> instance.
053 * Exceptions thrown by a subsequently executed Valve will be
054 * passed on to our caller.</p>
055 *
056 * <p>If there are no more Valves to be executed, execution of
057 * this method will result in a no op.</p>
058 *
059 * @param data The run-time information, including the servlet
060 * request and response we are processing.
061 *
062 * @exception IOException Thrown by a subsequent Valve.
063 * @exception TurbineException Thrown by a subsequent Valve.
064 * @exception TurbineException No further Valves configured in the
065 * Pipeline currently being processed.
066 */
067 public void invokeNext(PipelineData data)
068 throws IOException, TurbineException;
069 }