| /* |
| * Copyright 2003-2004 The Apache Software Foundation |
| * |
| * Licensed 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.directory.server.protocol.shared.chain; |
| |
| |
| /** |
| * <p>A {@link Filter} is a specialized {@link Command} that also expects |
| * the {@link Chain} that is executing it to call the |
| * <code>postprocess()</code> method if it called the <code>execute()</code> |
| * method. This promise must be fulfilled in spite of any possible |
| * exceptions thrown by the <code>execute()</code> method of this |
| * {@link Command}, or any subsequent {@link Command} whose |
| * <code>execute()</code> method was called. The owning {@link Chain} |
| * must call the <code>postprocess()</code> method of each {@link Filter} |
| * in a {@link Chain} in reverse order of the invocation of their |
| * <code>execute()</code> methods.</p> |
| * |
| * <p>The most common use case for a {@link Filter}, as opposed to a |
| * {@link Command}, is where potentially expensive resources must be acquired |
| * and held until the processing of a particular request has been completed, |
| * even it execution is delegated to a subsequent {@link Command} via the |
| * <code>execute()</code> returning <code>false</code>. A {@link Filter} |
| * can reliably release such resources in the <code>postprocess()</code> |
| * method, which is guaranteed to be called by the owning {@link Chain}.</p> |
| * |
| * @author Craig R. McClanahan |
| * @version $Revision$ $Date$ |
| */ |
| public interface Filter extends Command |
| { |
| /** |
| * <p>Execute any cleanup activities, such as releasing resources that |
| * were acquired during the <code>execute()</code> method of this |
| * {@link Filter} instance.</p> |
| * |
| * @param context The {@link Context} to be processed by this |
| * {@link Filter} |
| * @param exception The <code>Exception</code> (if any) that was thrown |
| * by the last {@link Command} that was executed; otherwise |
| * <code>null</code> |
| * |
| * @exception IllegalArgumentException if <code>context</code> |
| * is <code>null</code> |
| * |
| * @return If a non-null <code>exception</code> was "handled" by this |
| * method (and therefore need not be rethrown), return <code>true</code>; |
| * otherwise return <code>false</code> |
| */ |
| boolean postprocess( Context context, Exception exception ); |
| } |