/* * %W% %E% * * Copyright  1990-2006 Sun Microsystems, Inc. All Rights Reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER *  * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License version * 2 only, as published by the Free Software Foundation.  *  * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License version 2 for more details (a copy is * included at /legal/license.txt).  *  * You should have received a copy of the GNU General Public License * version 2 along with this work; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA * 02110-1301 USA  *  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa * Clara, CA 95054 or visit www.sun.com if you need additional * information or have any questions.  */package com.sun.jump.message;import java.io.IOException;import com.sun.jump.os.JUMPOSInterface;/** * <code>JUMPMessage</code> encapsulates the message header (envelope  * information) and the message payload. The message payload is an array * of bytes. * * The message is composed at a data offset determined by the OS. (obtained  * from <code>JUMPMessageQueueInterface.getDataOffset()</code>) * <p> * The message header consists of the following information * <ul> *   <li>Message ID - A unique identifier for the message</li> *   <li>Response Message ID - The message ID for which the message is a *       response. {@link #isResponseMessage()} indicates if a message is *       a response or not</li> *   <li>Sender - The sender of the message. If there are any responses to *       be sent, the sender's outhoing queue is used to send it. *       The sender is {@link com.sun.jump.message.JUMPMessagable}</li> *   <li>Message Type - An arbitrary string that identifies the message. This *       is typically used to tag or classify the message</li> * </ul> * <p> * * Instances of <Code>JUMPMessage</code> are manufactured from factories  * conforming to {@link com.sun.jump.message.JUMPMessagingService}  * */public abstract class JUMPMessage {    protected int messageDataOffset;    protected int messageMarkOffset;    protected int messageUserDataOffset;    protected byte[] messageDataBytes;    protected int MESSAGE_DATA_OFFSET =	JUMPOSInterface.getInstance().getQueueInterface().getDataOffset();        protected JUMPMessagable sender;    protected String type;    protected String returnType;    protected int id;    protected int responseId = -1;    /**     * Creates a new instance of JUMPMessage when     * deserializing an incoming message     */    protected JUMPMessage(byte[] data) {	this.messageDataBytes = data;	this.messageDataOffset = MESSAGE_DATA_OFFSET;	readHeader();    }        protected JUMPMessage() {    }    /**     * Get sender of this message in a form that allows the caller     * to send a response     */    public JUMPMessageResponseSender getSender() {        return this.getMessageSender();    }    public String getReturnType()     {	return this.returnType;    }        /**     * Returns the message type.     */    public String getType() {        return this.type;    }        /**     * Returns the message id     */    public int getId() {        return this.id;    }        /**     * Returns the response message id. The value makes sense only if     * {@link #isResponseMessage()} return true.     */    public int getResponseId() {        return this.responseId;    }        /**     * Return payload data offset     */    public int getPayloadDataOffset() {	return messageDataOffset;    }    /**     * Return payload      * (to be read at offset <code>getPayloadDataOffset()</code>)     */    public byte[] getPayload() {	return messageDataBytes;    }    /**     * Return payload (to be read at offset     * <code>JUMPMessageQueueInterface.getDataOffset()</code>)     */    public byte[] getMessageData() {	return messageDataBytes;    }    /**     * Indicates if this message is a response to a <code>JUMPMessage</code>     *      * @see #getResponseId     */    public boolean isResponseMessage() {        return this.responseId >= 0;    }        private void readHeader() {	JUMPMessageReader r = new JUMPMessageReader(this, MESSAGE_DATA_OFFSET);	this.id = r.getInt();	this.responseId = r.getInt();	readMessageSender(r.getInt());	this.returnType = r.getUTF();		this.type = r.getUTF();		// Update the offsets to point past the header	this.messageDataOffset = r.messageDataOffset;	this.messageUserDataOffset = messageDataOffset;	this.messageMarkOffset = messageDataOffset;	// User data follows    }    public void reset() {	messageDataOffset = messageMarkOffset;    }    protected abstract void readMessageSender(int id);    protected abstract JUMPMessageResponseSender getMessageSender();}