wireformatmessagefactory.java

JXTA&#8482 is a set of open, generalized peer-to-peer (P2P) protocols that allow any networked devi

/*
 * Copyright (c) 2001-2007 Sun Microsystems, Inc.  All rights reserved.
 *  
 *  The Sun Project JXTA(TM) Software License
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 *  modification, are permitted provided that the following conditions are met:
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 *  1. Redistributions of source code must retain the above copyright notice,
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 *     include the following acknowledgment: "This product includes software 
 *     developed by Sun Microsystems, Inc. for JXTA(TM) technology." 
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 *  <http://www.jxta.org/project/www/license.html> for instructions on use of 
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 *  ====================================================================
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 *  This software consists of voluntary contributions made by many individuals 
 *  on behalf of Project JXTA. For more information on Project JXTA, please see 
 *  http://www.jxta.org.
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 *  This license is based on the BSD license adopted by the Apache Foundation. 
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package net.jxta.endpoint;


import net.jxta.document.MimeMediaType;
import net.jxta.logging.Logging;
import net.jxta.util.ClassFactory;

import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.util.Hashtable;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.logging.Level;
import java.util.logging.Logger;


/**
 * This class is a class factory for Wire Format Messages. This class abstracts
 * The implementation of Wire Format Messages and allows for construction based
 * on the MimeType of InputStreams.
 * <p/>
 * The WireFormatMessageFactory extends the ClassFactory to register the
 * various Message wire format implementations into a static hashtable. The
 * factory is called with the Mime type requested to create the corresponding
 * Wire Format type.
 *
 * @see net.jxta.endpoint.Message
 * @see net.jxta.endpoint.WireFormatMessage
 * @see net.jxta.util.ClassFactory
 * @see net.jxta.document.MimeMediaType
 */
public final class WireFormatMessageFactory extends ClassFactory<MimeMediaType, WireFormatMessageFactory.Instantiator> {

    /**
     * Logger
     */
    private static final Logger LOG = Logger.getLogger(WireFormatMessageFactory.class.getName());

    /**
     * The mime media type of preferred/default wire format.
     */
    public static final MimeMediaType DEFAULT_WIRE_MIME = new MimeMediaType("application/x-jxta-msg").intern();

    /**
     * Interface for instantiators of wire format messages.
     */
    public interface Instantiator {

        /**
         * Returns the list of mime types supported by this serialization. All of
         * mimetypes in this list should have no mime type parameters.
         *
         * @return Returns the list of mime types supported by this serialization.
         */
        public MimeMediaType[] getSupportedMimeTypes();

        /**
         * Returns a list of the content encodings supported by this serialization.
         * These content encodings apply to both the overall coding of the message
         * and to the encoding of individual elements.
         *
         * @return a list of the content encodings supported by this serialization.
         */
        public MimeMediaType[] getSupportedContentEncodings();

        /**
         * Create a WireFormatMessage from an abstract message. It is an error
         * (though lazily enforced) to modify the abstract message during the
         * lifetime of the WireFormatMessage.
         *
         * @param msg                     the message for which a serialization is desired.
         * @param type                    the the serialization form desired. This can include
         *                                mime parameters to control options.
         * @param preferedContentEncoding An array of acceptable message encodings
         *                                in descending order of preference. any or none of these encoding options
         *                                may be used. May be null for unencoded messages.
         * @return a proxy object for the abstract message which is a
         *         representation of the message in its serialized form.
         */
        public WireFormatMessage toWire(Message msg, MimeMediaType type, MimeMediaType[] preferedContentEncoding);

        /**
         * Create an abstract message from a serialization.
         *
         * @param is              The message stream. Message serializations must either use
         *                        internal data or EOF to determine the length of the stream.
         * @param type            Declared message type of the stream including any optional
         *                        configuration parameters.
         * @param contentEncoding Content encoding (including optional parameters)
         *                        which has been applied to the message. May be null for unencoded messages.
         * @return a proxy object for the abstract message which is a
         *         representation of the message in its serialized form.
         * @throws java.io.IOException if an io error occurs
         */
        public Message fromWire(InputStream is, MimeMediaType type, MimeMediaType contentEncoding) throws IOException;

        /**
         * Create an abstract message from a serialization.
         *
         * @param buffer          The byte buffer. Message serializations must either use
         *                        internal data or EOF to determine the length of the stream.
         * @param type            Declared message type of the stream including any optional
         *                        configuration parameters.
         * @param contentEncoding Content encoding (including optional parameters)
         *                        which has been applied to the message. May be null for unencoded messages.
         * @return a proxy object for the abstract message which is a
         *         representation of the message in its serialized form.
         * @throws java.io.IOException if an io error occurs
         */
        public Message fromBuffer(ByteBuffer buffer, MimeMediaType type, MimeMediaType contentEncoding) throws IOException;
    }

    /**
     * This is the map of mime-types and constructors used by
     * <CODE>newStructuredDocument</CODE>.
     */
    private Map<MimeMediaType,Instantiator> encodings = new Hashtable<MimeMediaType,Instantiator>();

    /**
     * If true then the pre-defined set of StructuredDocument sub-classes has
     * been registered from the property containing them.
     */
    private volatile boolean loadedProperty = false;