/*
 *  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.api.IoSession;

/**
 * Decodes binary or protocol-specific data into higher-level message objects.
 *
 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
 * 
 */
public interface ProtocolDecoder<INPUT,OUTPUT> {

	/**
	 * Decode binary or protocol-specific content of type <code>INPUT</code> into higher-level protocol message objects, of type OUTPUT
	 * @param session the session for this message 
	 * @param input the received message to decode 
	 * @return the decoded message or <code>null</code> if nothing was decoded
	 */
	OUTPUT decode(IoSession session, INPUT input);
	
	/**
	 * Finish decoding, for example if the decoder accumulated some unused input, it should discard it, or throw an Exception
	 */
    void finishDecode(IoSession session);
}