/*
 *  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.mina.filter.codec;

import org.apache.mina.common.ByteBuffer;
import org.apache.mina.common.WriteFuture;

/**
 * Callback for {@link ProtocolEncoder} to generate encoded {@link ByteBuffer}s.
 * {@link ProtocolEncoder} must call {@link #write(ByteBuffer)} for each encoded
 * message.
 * 
 * @author The Apache Directory Project (mina-dev@directory.apache.org)
 * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (Fri, 13 Jul 2007) $
 */
public interface ProtocolEncoderOutput {
    /**
     * Callback for {@link ProtocolEncoder} to generate encoded
     * {@link ByteBuffer}s. {@link ProtocolEncoder} must call
     * {@link #write(ByteBuffer)} for each encoded message.
     * 
     * @param buf the buffer which contains encoded data
     */
    void write(ByteBuffer buf);

    /**
     * Merges all buffers you wrote via {@link #write(ByteBuffer)} into
     * one {@link ByteBuffer} and replaces the old fragmented ones with it.
     * This method is useful when you want to control the way MINA generates
     * network packets.
     */
    void mergeAll();

    /**
     * Flushes all buffers you wrote via {@link #write(ByteBuffer)} to
     * the session.  This operation is asynchronous; please wait for
     * the returned {@link WriteFuture} if you want to wait for
     * the buffers flushed.
     * 
     * @return <tt>null</tt> if there is nothing to flush at all.
     */
    WriteFuture flush();
}