FourMS
Class MessageListener

java.lang.Object
  FourMS.MessageListener

All Implemented Interfaces:

java.lang.Runnable, java.util.EventListener, javax.comm.SerialPortEventListener

public class MessageListener
extends java.lang.Object
implements java.lang.Runnable, javax.comm.SerialPortEventListener

This class is a threaded class which will be used to monitor the input port which will be responsible for piping into an application data that is coming from an input stream from for example, a 4MS simulator or from the 4MS itself. It will also be responsible for delagating incoming messages to a message handler which will not only parse the message for correctness, but also then pass the message on to the appropriate object which can then ascertain the messages semantics.

It should be noted that this class is used by both the 4MS instrument controller tasks and the simulation tasks as well

Version:

$Id: MessageListener.java,v 1.13 2006/05/18 09:19:43 cb Exp $

Author:

Craige Bevil

Field Summary

private int	BufferSize This is the default size of the incoming message buffer
(package private) java.net.Socket	clientSocket This is a connection to a simulator if there we are in simulation mode
private FourMSMessageHandler	ER412MessageHandler This object will be informed when a message comes in and it will be it's responsibility to handle the message and ultimately pass it on to another object which will have the responsibility of processing the message
private boolean	FourMSTransceiverClient Signifies if this is a 4MS transceiver client
private java.io.BufferedReader	inputStream These will be used for sending and receiving from the 4MS simulator
private java.io.InputStreamReader	portServerInputStream This will be used for sending data back to the
private java.lang.String	PortServerPort This is the name of the port on the local machine which we will open in order to communicate with the port server should be running with a portserver.
private char[]	readBuffer This is a buffer into which data will be read from the portserver and then stored.
private java.lang.Thread	Runner This object runs within it's own thread
(package private) javax.comm.SerialPort	serialPort If we are connected to a port server then this is the file handle through which we can send and receive data
private int	SocketNumber In the case that we are using a standard TCP/IP socket to connect to the ER412 transmitter, we need to know the port number of the listening socket which we need to open
private int	SocketType This is the type of socket which is being used.
private MessageHandler	SyslogMessageHandler This is a syslog object which will be used to report errors etc
(package private) java.net.ServerSocket	TCPIPServerSocket This holds the TCP/IP server socket which will be used for communication should we be using normal TCP/IP for communication with the ER412 transmitter
private long	TimeOfLast4MSComms This is used to get the time of the last comms from the 4MS which is attached

Constructor Summary

MessageListener(boolean FourMSTransceiverClient, int SocketNumber, int BufferSize, FourMSMessageHandler ER412MessageHandler, MessageHandler SyslogMessageHandler)
This is the constructor for the class which will be used to define an object that will use a TCP/IP socket for input.

MessageListener(java.lang.String PortServerPort, FourMSMessageHandler ER412MessageHandler, MessageHandler SyslogMessageHandler)
This is the constructor which will be used to set up th message listener so that it will talk to FourMS instrument through a port portserver.

Method Summary

long	getTimeOfLast4MSComms() This will return the time of the last communications with the 4MS module
void	listenForInput() When called it starts the listening thread which will result in the object listening for input from the simulator if we are in simulation mode or alternatively, from the 4MS portserver.
void	run() This satifies the requirement of the runnable interface as this object has it's own thread This method is called and results in the object going into a wait state waiting for input from the transmitter and subsequently sending the incoming data onto the message handler.
void	serialEvent(javax.comm.SerialPortEvent event) This is the event handler which will be called when there is an event on the portserver serial port file descriptor .
void	setupPortServerPort() This will be used to open up the serial port which goes out to the portserver and subsequently out to the 4MS.
void	shutdownConnections() Closes down the connection to the portserver or the simulator.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

clientSocket

java.net.Socket clientSocket

This is a connection to a simulator if there we are in simulation mode

serialPort

javax.comm.SerialPort serialPort

If we are connected to a port server then this is the file handle through which we can send and receive data

readBuffer

private char[] readBuffer

This is a buffer into which data will be read from the portserver and then stored.

inputStream

private java.io.BufferedReader inputStream

These will be used for sending and receiving from the 4MS simulator

portServerInputStream

private java.io.InputStreamReader portServerInputStream

This will be used for sending data back to the

BufferSize

private int BufferSize

This is the default size of the incoming message buffer

SocketType

private int SocketType

This is the type of socket which is being used. This can either be a standard TCP/IP connection or it can be a port server connection.

SocketNumber

private int SocketNumber

In the case that we are using a standard TCP/IP socket to connect to the ER412 transmitter, we need to know the port number of the listening socket which we need to open

FourMSTransceiverClient

private boolean FourMSTransceiverClient

Signifies if this is a 4MS transceiver client

ER412MessageHandler

private FourMSMessageHandler ER412MessageHandler

This object will be informed when a message comes in and it will be it's responsibility to handle the message and ultimately pass it on to another object which will have the responsibility of processing the message

Runner

private java.lang.Thread Runner

This object runs within it's own thread

TimeOfLast4MSComms

private long TimeOfLast4MSComms

This is used to get the time of the last comms from the 4MS which is attached

PortServerPort

private java.lang.String PortServerPort

This is the name of the port on the local machine which we will open in order to communicate with the port server should be running with a portserver.

SyslogMessageHandler

private MessageHandler SyslogMessageHandler

This is a syslog object which will be used to report errors etc

TCPIPServerSocket

java.net.ServerSocket TCPIPServerSocket

This holds the TCP/IP server socket which will be used for communication should we be using normal TCP/IP for communication with the ER412 transmitter

Constructor Detail

MessageListener

public MessageListener(java.lang.String PortServerPort,
                       FourMSMessageHandler ER412MessageHandler,
                       MessageHandler SyslogMessageHandler)

This is the constructor which will be used to set up th message listener so that it will talk to FourMS instrument through a port portserver.

Parameters:

PortServerPort - This is the name of the device which will be used to communicate with the portserver

ER412MessageHandler - This will be used for parsing and delagating incoming messages from the 4MS to other objects for assigning semantic actions to the messages

SyslogMessageHandler - This will be used for reporting errors

MessageListener

public MessageListener(boolean FourMSTransceiverClient,
                       int SocketNumber,
                       int BufferSize,
                       FourMSMessageHandler ER412MessageHandler,
                       MessageHandler SyslogMessageHandler)

This is the constructor for the class which will be used to define an object that will use a TCP/IP socket for input. This constructor will be called in the case that the system will be run in simulation mode. The simulator software will call this constructor and the instrument controller software will call this method should it determine that it has been instructed to run in simulation mode.

Parameters:

FourMSTransceiverClient - If this is true then we consider ourselves to be a ER412 client.

SocketNumber - - This is the socket number to open a listening socket upon in the case that we will be using standard TCP/IP sockets in order to connect to the 4MS controller software from the simulator

BufferSize - This is the size of the input buffer which is to be used by the object

ER412MessageHandler - This will be used by the class when handing over incoming messages to another object for processing

SyslogMessageHandler - This is the syslog handler which will be used for reporting errors when they occur

Method Detail

getTimeOfLast4MSComms

public long getTimeOfLast4MSComms()

This will return the time of the last communications with the 4MS module

Returns:

long Time in seconds since 1st Jan 1970 when the last communications were recived from the 4MS module

setupPortServerPort

public void setupPortServerPort()

This will be used to open up the serial port which goes out to the portserver and subsequently out to the 4MS. The source of the name of the port to be used is held in the WHT ICS database table instrument.

The transmission characteristics for the 4MS modules and the portserver are set to the following;

Characteristic	Setting
Baud	9600
Stop bits	1
Parity	Even
Data bits	7
XON/XOFF	On

listenForInput

public void listenForInput()

When called it starts the listening thread which will result in the object listening for input from the simulator if we are in simulation mode or alternatively, from the 4MS portserver.

run

public void run()

This satifies the requirement of the runnable interface as this object has it's own thread This method is called and results in the object going into a wait state waiting for input from the transmitter and subsequently sending the incoming data onto the message handler.

Note that in the case that we are connected to a portserver using the javax.comm API, events on that port will come into the application (such as incoming data) and processed through the SerialPortEventListener method.

Specified by:

run in interface java.lang.Runnable

serialEvent

public void serialEvent(javax.comm.SerialPortEvent event)

This is the event handler which will be called when there is an event on the portserver serial port file descriptor . The only event we are registered for is the DATA_AVAILABLE event which is called when there is input coming from the 4MS module.

This method is not used when the software is running in simulation mode.

Specified by:

serialEvent in interface javax.comm.SerialPortEventListener

Parameters:

event - This contains the details of the event on the serial port.

shutdownConnections

public void shutdownConnections()

Closes down the connection to the portserver or the simulator.