java source code of UDPSlaveTerminal

/***
 * Copyright 2002-2010 jamod development team
 *
 * Licensed 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.
 * 
 * Original implementation by jamod development team.
 * This file modified by Charles Hache <[email protected]>
 ***/

package net.wimpi.modbus.net;

import net.wimpi.modbus.Modbus;
import net.wimpi.modbus.io.ModbusUDPTransport;
import net.wimpi.modbus.util.LinkedQueue;
import net.wimpi.modbus.util.ModbusUtil;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.util.Hashtable;

/**
 * Class implementing a <tt>UDPSlaveTerminal</tt>.
 * 
 * @author Dieter Wimberger
 * @version @version@ (@date@)
 */
class UDPSlaveTerminal implements UDPTerminal {

	// instance attributes
	private DatagramSocket m_Socket;
	// private int m_Timeout = Modbus.DEFAULT_TIMEOUT;
	private boolean m_Active;
	protected InetAddress m_LocalAddress;
	private int m_LocalPort = Modbus.DEFAULT_PORT;
	protected ModbusUDPTransport m_ModbusTransport;
	// private int m_Retries = Modbus.DEFAULT_RETRIES;

	private LinkedQueue m_SendQueue;
	private LinkedQueue m_ReceiveQueue;
	private PacketSender m_PacketSender;
	private PacketReceiver m_PacketReceiver;
	private Thread m_Receiver;
	private Thread m_Sender;

	protected Hashtable<Integer, DatagramPacket> m_Requests;

	protected UDPSlaveTerminal() {
		m_SendQueue = new LinkedQueue();
		m_ReceiveQueue = new LinkedQueue();
		m_Requests = new Hashtable<Integer, DatagramPacket>(342);
	}// constructor

	protected UDPSlaveTerminal(InetAddress localaddress) {
		m_LocalAddress = localaddress;
		m_SendQueue = new LinkedQueue();
		m_ReceiveQueue = new LinkedQueue();
		m_Requests = new Hashtable<Integer, DatagramPacket>(342);
	}// constructor

	public InetAddress getLocalAddress() {
		return m_LocalAddress;
	}// getLocalAddress

	public int getLocalPort() {
		return m_LocalPort;
	}// getLocalPort

	protected void setLocalPort(int port) {
		m_LocalPort = port;
	}// setLocalPort

	/**
	 * Tests if this <tt>UDPSlaveTerminal</tt> is active.
	 * 
	 * @return <tt>true</tt> if active, <tt>false</tt> otherwise.
	 */
	public boolean isActive() {
		return m_Active;
	}// isActive

	/**
	 * Activate this <tt>UDPTerminal</tt>.
	 * 
	 * @throws Exception
	 *             if there is a network failure.
	 */
	public synchronized void activate() throws Exception {
		if (!isActive()) {
			if (Modbus.debug)
				System.out.println("UDPSlaveTerminal::activate()");
			if (m_Socket == null) {
				if (m_LocalAddress != null && m_LocalPort != -1) {
					m_Socket = new DatagramSocket(m_LocalPort, m_LocalAddress);
				} else {
					m_Socket = new DatagramSocket();
					m_LocalPort = m_Socket.getLocalPort();
					m_LocalAddress = m_Socket.getLocalAddress();
				}
			}
			if (Modbus.debug)
				System.out.println("UDPSlaveTerminal::haveSocket():"
						+ m_Socket.toString());
			if (Modbus.debug)
				System.out.println("UDPSlaveTerminal::addr=:"
						+ m_LocalAddress.toString() + ":port=" + m_LocalPort);

			m_Socket.setReceiveBufferSize(1024);
			m_Socket.setSendBufferSize(1024);
			m_PacketReceiver = new PacketReceiver();
			m_Receiver = new Thread(m_PacketReceiver);
			m_Receiver.start();
			if (Modbus.debug)
				System.out.println("UDPSlaveTerminal::receiver started()");
			m_PacketSender = new PacketSender();
			m_Sender = new Thread(m_PacketSender);
			m_Sender.start();
			if (Modbus.debug)
				System.out.println("UDPSlaveTerminal::sender started()");
			m_ModbusTransport = new ModbusUDPTransport(this);
			if (Modbus.debug)
				System.out.println("UDPSlaveTerminal::transport created");
			m_Active = true;
		}
		if (Modbus.debug)
			System.out.println("UDPSlaveTerminal::activated");
	}// activate

	/**
	 * Deactivates this <tt>UDPSlaveTerminal</tt>.
	 */
	public void deactivate() {
		try {
			if (m_Active) {
				// 1. stop receiver
				m_PacketReceiver.stop();
				m_Receiver.join();
				// 2. stop sender gracefully
				m_PacketSender.stop();
				m_Sender.join();
				// 3. close socket
				m_Socket.close();
				m_ModbusTransport = null;
				m_Active = false;
			}
		} catch (Exception ex) {
			ex.printStackTrace();
		}
	}// deactivate

	/**
	 * Returns the <tt>ModbusTransport</tt> associated with this
	 * <tt>TCPMasterConnection</tt>.
	 * 
	 * @return the connection's <tt>ModbusTransport</tt>.
	 */
	public ModbusUDPTransport getModbusTransport() {
		return m_ModbusTransport;
	}// getModbusTransport

	protected boolean hasResponse() {
		return !m_ReceiveQueue.isEmpty();
	}// hasResponse

	/**
	 * Returns the timeout for this <tt>UDPSlaveTerminal</tt>.
	 * 
	 * @return the timeout as <tt>int</tt>.
	 * 
	 *         public int getReceiveTimeout() { return m_Timeout;
	 *         }//getReceiveTimeout
	 * 
	 *         /** Sets the timeout for this <tt>UDPSlaveTerminal</tt>.
	 * 
	 * @param timeout
	 *            the timeout as <tt>int</tt>.
	 * 
	 *            public void setReceiveTimeout(int timeout) { m_Timeout =
	 *            timeout; try { m_Socket.setSoTimeout(m_Timeout); } catch
	 *            (IOException ex) { ex.printStackTrace(); //handle? }
	 *            }//setReceiveTimeout
	 */
	/**
	 * Returns the socket of this <tt>UDPSlaveTerminal</tt>.
	 * 
	 * @return the socket as <tt>DatagramSocket</tt>.
	 */
	public DatagramSocket getSocket() {
		return m_Socket;
	}// getSocket

	/**
	 * Sets the socket of this <tt>UDPTerminal</tt>.
	 * 
	 * @param sock
	 *            the <tt>DatagramSocket</tt> for this terminal.
	 */
	protected void setSocket(DatagramSocket sock) {
		m_Socket = sock;
	}// setSocket

	public void sendMessage(byte[] msg) throws Exception {
		m_SendQueue.put(msg);
	}// sendPackage

	public byte[] receiveMessage() throws Exception {
		return (byte[]) m_ReceiveQueue.take();
	}// receiveMessage

	class PacketSender implements Runnable {

		private boolean m_Continue;

		public PacketSender() {
			m_Continue = true;
		}// constructor

		public void run() {
			do {
				try {
					// 1. pickup the message and corresponding request
					byte[] message = (byte[]) m_SendQueue.take();
					DatagramPacket req = (DatagramPacket) m_Requests
							.remove(new Integer(ModbusUtil
									.registersToInt(message)));
					// 2. create new Package with corresponding address and port
					DatagramPacket res = new DatagramPacket(message,
							message.length, req.getAddress(), req.getPort());
					m_Socket.send(res);
					if (Modbus.debug)
						System.out.println("Sent package from queue.");
				} catch (Exception ex) {
					ex.printStackTrace();
				}
			} while (m_Continue || !m_SendQueue.isEmpty());
		}// run

		public void stop() {
			m_Continue = false;
		}// stop

	}// PacketSender

	class PacketReceiver implements Runnable {

		private boolean m_Continue;

		public PacketReceiver() {
			m_Continue = true;
		}// constructor

		public void run() {
			do {
				try {
					// 1. Prepare buffer and receive package
					byte[] buffer = new byte[256];// max size
					DatagramPacket packet = new DatagramPacket(buffer,
							buffer.length);
					m_Socket.receive(packet);
					// 2. Extract TID and remember request
					Integer tid = new Integer(ModbusUtil.registersToInt(buffer));
					m_Requests.put(tid, packet);
					// 3. place the data buffer in the queue
					m_ReceiveQueue.put(buffer);
					if (Modbus.debug)
						System.out.println("Received package to queue.");
				} catch (Exception ex) {
					ex.printStackTrace();
				}
			} while (m_Continue);
		}// run

		public void stop() {
			m_Continue = false;
		}// stop

	}// PacketReceiver

}// class UDPTerminal