/* * %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; /** * JUMPMessage 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 JUMPMessageQueueInterface.getDataOffset()) * * The message header consists of the following information * * Message ID - A unique identifier for the message * Response Message ID - The message ID for which the message is a * response. {@link #isResponseMessage()} indicates if a message is * a response or not * 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} * Message Type - An arbitrary string that identifies the message. This * is typically used to tag or classify the message * * * * Instances of JUMPMessage 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 getPayloadDataOffset()) */ public byte[] getPayload() { return messageDataBytes; } /** * Return payload (to be read at offset * JUMPMessageQueueInterface.getDataOffset()) */ public byte[] getMessageData() { return messageDataBytes; } /** * Indicates if this message is a response to a JUMPMessage * * @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(); }
