001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *    http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 *
019 */
020package org.apache.mina.core.filterchain;
021
022import org.apache.mina.core.session.IoSession;
023
024/**
025 * An interface that builds {@link IoFilterChain} in predefined way
026 * when {@link IoSession} is created.  You can extract common filter chain
027 * modification logic to this interface.  For example, to add a filter
028 * to the chain,
029 * <pre>
030 * public class MyFilterChainBuilder implements IoFilterChainBuilder {
031 *     public void buildFilterChain( IoFilterChain chain ) throws Exception {
032 *         chain.addLast( "myFilter", new MyFilter() );
033 *     }
034 * }
035 * </pre>
036 *
037 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
038 */
039public interface IoFilterChainBuilder {
040    /**
041     * An implementation which does nothing.
042     */
043    IoFilterChainBuilder NOOP = new IoFilterChainBuilder() {
044        public void buildFilterChain(IoFilterChain chain) throws Exception {
045        }
046
047        @Override
048        public String toString() {
049            return "NOOP";
050        }
051    };
052
053    /**
054     * Modifies the specified <tt>chain</tt>.
055     * 
056     * @param chain The chain to modify
057     * @throws Exception If the chain modification failed
058     */
059    void buildFilterChain(IoFilterChain chain) throws Exception;
060}