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The Core Camel Java DSL based router
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/**
 * 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.camel.spi;

import java.io.InputStream;
import java.io.OutputStream;

import org.apache.camel.Exchange;
import org.apache.camel.Message;

/**
 * Represents a
 * data format
 * used to marshal objects to and from streams
 * such as Java Serialization or using JAXB2 to encode/decode objects using XML
 * or using SOAP encoding.
 *
 * @version 
 */
public interface DataFormat {

    // TODO: DataFormats should extends Service like the others

    /**
     * Marshals the object to the given Stream.
     *
     * @param exchange  the current exchange
     * @param graph     the object to be marshalled
     * @param stream    the output stream to write the marshalled result to
     * @throws Exception can be thrown
     */
    void marshal(Exchange exchange, Object graph, OutputStream stream) throws Exception;

    /**
     * Unmarshals the given stream into an object.
     * 
     * Notice: The result is set as body on the exchange OUT message.
     * It is possible to mutate the OUT message provided in the given exchange parameter.
     * For instance adding headers to the OUT message will be preserved.
     * 
     * It's also legal to return the same passed exchange as is but also a
     * {@link Message} object as well which will be used as the OUT message of exchange.
     *
     * @param exchange    the current exchange
     * @param stream      the input stream with the object to be unmarshalled
     * @return            the unmarshalled object
     * @throws Exception can be thrown
     */
    Object unmarshal(Exchange exchange, InputStream stream) throws Exception;
}