/**
 * Copyright 2007-2016, Kaazing Corporation. All rights reserved.
 *
 * 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.mina.filter.codec;

import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.file.FileRegion;
import org.apache.mina.core.future.WriteFuture;

/**
 * Callback for {@link ProtocolEncoder} to generate encoded messages such as
 * {@link IoBuffer}s.  {@link ProtocolEncoder} must call {@link #write(Object)}
 * for each encoded message.
 *
 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
 */
public interface ProtocolEncoderOutput {
    /**
     * Callback for {@link ProtocolEncoder} to generate an encoded message such
     * as an {@link IoBuffer}. {@link ProtocolEncoder} must call
     * {@link #write(Object)} for each encoded message.
     *
     * @param encodedMessage the encoded message, typically an {@link IoBuffer}
     *                       or a {@link FileRegion}.
     */
    void write(Object encodedMessage);

    /**
     * Merges all buffers you wrote via {@link #write(Object)} into
     * one {@link IoBuffer} and replaces the old fragmented ones with it.
     * This method is useful when you want to control the way MINA generates
     * network packets.  Please note that this method only works when you
     * called {@link #write(Object)} method with only {@link IoBuffer}s.
     * 
     * @throws IllegalStateException if you wrote something else than {@link IoBuffer}
     */
    void mergeAll();

    /**
     * Flushes all buffers you wrote via {@link #write(Object)} 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();
}