123 lines
4.9 KiB
Java
123 lines
4.9 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.catalina;
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import java.io.IOException;
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import javax.servlet.ServletException;
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import org.apache.catalina.connector.Request;
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import org.apache.catalina.connector.Response;
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/**
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* <p>A <b>Valve</b> is a request processing component associated with a
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* particular Container. A series of Valves are generally associated with
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* each other into a Pipeline. The detailed contract for a Valve is included
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* in the description of the <code>invoke()</code> method below.</p>
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*
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* <b>HISTORICAL NOTE</b>: The "Valve" name was assigned to this concept
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* because a valve is what you use in a real world pipeline to control and/or
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* modify flows through it.
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*
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* @author Craig R. McClanahan
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* @author Gunnar Rjnning
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* @author Peter Donald
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*/
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public interface Valve {
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//-------------------------------------------------------------- Properties
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/**
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* @return the next Valve in the pipeline containing this Valve, if any.
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*/
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public Valve getNext();
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/**
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* Set the next Valve in the pipeline containing this Valve.
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*
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* @param valve The new next valve, or <code>null</code> if none
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*/
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public void setNext(Valve valve);
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//---------------------------------------------------------- Public Methods
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/**
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* Execute a periodic task, such as reloading, etc. This method will be
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* invoked inside the classloading context of this container. Unexpected
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* throwables will be caught and logged.
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*/
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public void backgroundProcess();
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/**
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* <p>Perform request processing as required by this Valve.</p>
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*
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* <p>An individual Valve <b>MAY</b> perform the following actions, in
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* the specified order:</p>
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* <ul>
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* <li>Examine and/or modify the properties of the specified Request and
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* Response.
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* <li>Examine the properties of the specified Request, completely generate
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* the corresponding Response, and return control to the caller.
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* <li>Examine the properties of the specified Request and Response, wrap
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* either or both of these objects to supplement their functionality,
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* and pass them on.
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* <li>If the corresponding Response was not generated (and control was not
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* returned, call the next Valve in the pipeline (if there is one) by
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* executing <code>getNext().invoke()</code>.
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* <li>Examine, but not modify, the properties of the resulting Response
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* (which was created by a subsequently invoked Valve or Container).
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* </ul>
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*
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* <p>A Valve <b>MUST NOT</b> do any of the following things:</p>
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* <ul>
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* <li>Change request properties that have already been used to direct
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* the flow of processing control for this request (for instance,
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* trying to change the virtual host to which a Request should be
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* sent from a pipeline attached to a Host or Context in the
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* standard implementation).
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* <li>Create a completed Response <strong>AND</strong> pass this
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* Request and Response on to the next Valve in the pipeline.
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* <li>Consume bytes from the input stream associated with the Request,
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* unless it is completely generating the response, or wrapping the
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* request before passing it on.
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* <li>Modify the HTTP headers included with the Response after the
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* <code>getNext().invoke()</code> method has returned.
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* <li>Perform any actions on the output stream associated with the
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* specified Response after the <code>getNext().invoke()</code> method has
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* returned.
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* </ul>
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*
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* @param request The servlet request to be processed
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* @param response The servlet response to be created
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*
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* @exception IOException if an input/output error occurs, or is thrown
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* by a subsequently invoked Valve, Filter, or Servlet
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* @exception ServletException if a servlet error occurs, or is thrown
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* by a subsequently invoked Valve, Filter, or Servlet
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*/
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public void invoke(Request request, Response response)
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throws IOException, ServletException;
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public boolean isAsyncSupported();
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}
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