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.filter.codec;
021
022import org.apache.mina.core.buffer.IoBuffer;
023import org.apache.mina.core.file.FileRegion;
024import org.apache.mina.core.future.WriteFuture;
025
026/**
027 * Callback for {@link ProtocolEncoder} to generate encoded messages such as
028 * {@link IoBuffer}s.  {@link ProtocolEncoder} must call {@link #write(Object)}
029 * for each encoded message.
030 *
031 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
032 */
033public interface ProtocolEncoderOutput {
034    /**
035     * Callback for {@link ProtocolEncoder} to generate an encoded message such
036     * as an {@link IoBuffer}. {@link ProtocolEncoder} must call
037     * {@link #write(Object)} for each encoded message.
038     *
039     * @param encodedMessage the encoded message, typically an {@link IoBuffer}
040     *                       or a {@link FileRegion}.
041     */
042    void write(Object encodedMessage);
043
044    /**
045     * Merges all buffers you wrote via {@link #write(Object)} into
046     * one {@link IoBuffer} and replaces the old fragmented ones with it.
047     * This method is useful when you want to control the way MINA generates
048     * network packets.  Please note that this method only works when you
049     * called {@link #write(Object)} method with only {@link IoBuffer}s.
050     * 
051     * @throws IllegalStateException if you wrote something else than {@link IoBuffer}
052     */
053    void mergeAll();
054
055    /**
056     * Flushes all buffers you wrote via {@link #write(Object)} to
057     * the session.  This operation is asynchronous; please wait for
058     * the returned {@link WriteFuture} if you want to wait for
059     * the buffers flushed.
060     *
061     * @return <tt>null</tt> if there is nothing to flush at all.
062     */
063    WriteFuture flush();
064}