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    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   * <p>A <b>ValveContext</b> is the mechanism by which a Valve can trigger the
    30   * execution of the next Valve in a Pipeline, without having to know anything
    31   * about the internal implementation mechanisms.  An instance of a class
    32   * implementing this interface is passed as a parameter to the
    33   * <code>Valve.invoke()</code> method of each executed Valve.</p>
    34   *
    35   * <p><strong>IMPLEMENTATION NOTE</strong>: It is up to the implementation of
    36   * ValveContext to ensure that simultaneous requests being processed (by
    37   * separate threads) through the same Pipeline do not interfere with each
    38   * other's flow of control.</p>
    39   *
    40   * @author Craig R. McClanahan
    41   * @author Gunnar Rjnning
    42   * @author Peter Donald
    43   * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
    44   * @version $Revision: 615328 $ $Date: 2008-01-25 21:25:05 +0100 (Fr, 25 Jan 2008) $
    45   */
    46  public interface ValveContext
    47  {
    48      /**
    49       * <p>Cause the <code>invoke()</code> method of the next Valve
    50       * that is part of the Pipeline currently being processed (if any)
    51       * to be executed, passing on the specified request and response
    52       * objects plus this <code>ValveContext</code> instance.
    53       * Exceptions thrown by a subsequently executed Valve will be
    54       * passed on to our caller.</p>
    55       *
    56       * <p>If there are no more Valves to be executed, execution of
    57       * this method will result in a no op.</p>
    58       *
    59       * @param data The run-time information, including the servlet
    60       * request and response we are processing.
    61       *
    62       * @exception IOException Thrown by a subsequent Valve.
    63       * @exception TurbineException Thrown by a subsequent Valve.
    64       * @exception TurbineException No further Valves configured in the
    65       * Pipeline currently being processed.
    66       */
    67      public void invokeNext(PipelineData data)
    68          throws IOException, TurbineException;
    69  }