| package org.apache.turbine.pipeline; |
| |
| /* ==================================================================== |
| * The Apache Software License, Version 1.1 |
| * |
| * Copyright (c) 2001 The Apache Software Foundation. All rights |
| * reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * 3. The end-user documentation included with the redistribution, |
| * if any, must include the following acknowledgment: |
| * "This product includes software developed by the |
| * Apache Software Foundation (http://www.apache.org/)." |
| * Alternately, this acknowledgment may appear in the software itself, |
| * if and wherever such third-party acknowledgments normally appear. |
| * |
| * 4. The names "Apache" and "Apache Software Foundation" and |
| * "Apache Turbine" must not be used to endorse or promote products |
| * derived from this software without prior written permission. For |
| * written permission, please contact apache@apache.org. |
| * |
| * 5. Products derived from this software may not be called "Apache", |
| * "Apache Turbine", nor may "Apache" appear in their name, without |
| * prior written permission of the Apache Software Foundation. |
| * |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR |
| * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
| * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * ==================================================================== |
| * |
| * This software consists of voluntary contributions made by many |
| * individuals on behalf of the Apache Software Foundation. For more |
| * information on the Apache Software Foundation, please see |
| * <http://www.apache.org/>. |
| */ |
| |
| import java.io.IOException; |
| |
| import org.apache.turbine.util.RunData; |
| import org.apache.turbine.util.TurbineException; |
| |
| /** |
| * <p>A <b>Valve</b> is a request processing component. A series of |
| * Valves are generally associated with each other into a Pipeline. |
| * The detailed contract for a Valve is included in the description of |
| * the <code>invoke()</code> method below.</p> |
| * |
| * <b>HISTORICAL NOTE</b>: The "Valve" name was assigned to this concept |
| * because a valve is what you use in a real world pipeline to control and/or |
| * modify flows through it. |
| * |
| * @author Craig R. McClanahan |
| * @author Gunnar Rjnning |
| * @author Peter Donald |
| * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a> |
| * |
| * @see #invoke(RunData, ValveContext) |
| */ |
| public interface Valve |
| { |
| /** |
| * <p>Perform request processing as required by this Valve.</p> |
| * |
| * <p>An individual Valve <b>MAY</b> perform the following actions, in |
| * the specified order:</p> |
| * <ul> |
| * <li>Examine and/or modify the properties of the specified Request and |
| * Response. |
| * <li>Examine the properties of the specified Request, completely generate |
| * the corresponding Response, and return control to the caller. |
| * <li>Examine the properties of the specified Request and Response, wrap |
| * either or both of these objects to supplement their functionality, |
| * and pass them on. |
| * <li>If the corresponding Response was not generated (and control was not |
| * returned, call the next Valve in the pipeline (if there is one) by |
| * executing <code>context.invokeNext()</code>. |
| * <li>Examine, but not modify, the properties of the resulting Response |
| * (which was created by a subsequently invoked Valve via a |
| * call to <code>context.invokeNext()</code>). |
| * </ul> |
| * |
| * <p>A Valve <b>MUST NOT</b> do any of the following things:</p> |
| * <ul> |
| * <li>Change request properties that have already been used to direct |
| * the flow of processing control for this request. |
| * <li>Create a completed Response <strong>AND</strong> pass this |
| * Request and Response on to the next Valve in the pipeline. |
| * <li>Consume bytes from the input stream associated with the Request, |
| * unless it is completely generating the response, or wrapping the |
| * request before passing it on. |
| * <li>Modify the HTTP headers included with the Response after the |
| * <code>invokeNext()</code> method has returned. |
| * <li>Perform any actions on the output stream associated with the |
| * specified Response after the <code>invokeNext()</code> method has |
| * returned. |
| * </ul> |
| * |
| * @param data The run-time information, including the servlet |
| * request and response we are processing. |
| * @param context The valve context used to invoke the next valve |
| * in the current processing pipeline |
| * |
| * @exception IOException Thrown by a subsequent Valve. |
| * @exception TurbineException Thrown by a subsequent Valve. |
| */ |
| public void invoke(PipelineData data, ValveContext context) |
| throws IOException, TurbineException; |
| |
| /** |
| * Initialize the valve before using in a pipeline. |
| */ |
| public void initialize() |
| throws Exception; |
| } |