content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  package org.apache.guacamole.protocol;
  
  import org.apache.guacamole.GuacamoleException;
  
  /**
   * Interface which provides for the filtering of individual instructions. Each
   * filtered instruction may be allowed through untouched, modified, replaced,
   * dropped, or explicitly denied.
   *
   * @author Michael Jumper
   */
  public interface GuacamoleFilter {
  
      /**
       * Applies the filter to the given instruction, returning the original
       * instruction, a modified version of the original, or null, depending
       * on the implementation.
       *
       * @param instruction The instruction to filter.
       * @return The original instruction, if the instruction is to be allowed,
       *         a modified version of the instruction, if the instruction is
       *         to be overridden, or null, if the instruction is to be dropped.
       * @throws GuacamoleException If an error occurs filtering the instruction,
       *                            or if the instruction must be explicitly
       *                            denied.
       */
      public GuacamoleInstruction filter(GuacamoleInstruction instruction) throws GuacamoleException;
      
  }
  