001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.spi;
018
019import java.io.InputStream;
020import java.io.OutputStream;
021
022import org.apache.camel.Exchange;
023import org.apache.camel.Message;
024
025/**
026 * Represents a
027 * <a href="http://camel.apache.org/data-format.html">data format</a>
028 * used to marshal objects to and from streams
029 * such as Java Serialization or using JAXB2 to encode/decode objects using XML
030 * or using SOAP encoding.
031 *
032 * @version 
033 */
034public interface DataFormat {
035
036    // TODO: DataFormats should extends Service like the others
037
038    /**
039     * Marshals the object to the given Stream.
040     *
041     * @param exchange  the current exchange
042     * @param graph     the object to be marshalled
043     * @param stream    the output stream to write the marshalled result to
044     * @throws Exception can be thrown
045     */
046    void marshal(Exchange exchange, Object graph, OutputStream stream) throws Exception;
047
048    /**
049     * Unmarshals the given stream into an object.
050     * <p/>
051     * <b>Notice:</b> The result is set as body on the exchange OUT message.
052     * It is possible to mutate the OUT message provided in the given exchange parameter.
053     * For instance adding headers to the OUT message will be preserved.
054     * <p/>
055     * It's also legal to return the <b>same</b> passed <tt>exchange</tt> as is but also a
056     * {@link Message} object as well which will be used as the OUT message of <tt>exchange</tt>.
057     *
058     * @param exchange    the current exchange
059     * @param stream      the input stream with the object to be unmarshalled
060     * @return            the unmarshalled object
061     * @throws Exception can be thrown
062     */
063    Object unmarshal(Exchange exchange, InputStream stream) throws Exception;
064}