Package org.apache.uima.pear.util

Class MessageRouter

java.lang.Object

org.apache.uima.pear.util.MessageRouter

All Implemented Interfaces:

java.lang.Runnable

public class MessageRouter
extends java.lang.Object
implements java.lang.Runnable

The MessageRouter class facilitates intra-process message routing. It provides application classes with convenient access to the message channels via the PrintWriter class. The MessageRouter class, by default, defines 2 standard message channels - for standard output and standard error messages. Applications can publish their standard output and standard error messages using the outWriter() and errWriter() methods correspondingly.
The MessageRouter class distributes the messages to a number of message channel listeners, added by applications. Standard message channel listeners should implement the MessageRouter.StdChannelListener interface. The MessageRouter class collects all published messages. When a new message channel listener is added, it receives all collected messages from the message history.

The MessageRouter code runs in a separate thread that should be started and terminated by applications. Applications should use the start() and terminate() methods to start and terminate the MessageRouter thread correspondingly.
For terminology see the Enterprise Integration Patterns book.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	MessageRouter.StdChannelListener	The StdChannelListener interface declares methods that should be implemented by each standard message channel listener.

Field Summary

Fields

Modifier and Type	Field	Description
private java.lang.StringBuffer	_errBuffer
private int	_errOffset
private java.io.StringWriter	_errStream
private java.io.PrintWriter	_errWriter
private java.lang.StringBuffer	_outBuffer
private int	_outOffset
private java.io.StringWriter	_outStream
private java.io.PrintWriter	_outWriter
private java.util.List<java.lang.String>	_stdHistory
private java.util.List<MessageRouter.StdChannelListener>	_stdListeners
private boolean	_terminated
private java.lang.Thread	_thread
private static java.lang.String	ERR_MSG_ID
private static java.lang.String	OUT_MSG_ID
private static long	WAITING_TIME

Constructor Summary

Constructors

Constructor	Description
MessageRouter()	Default constructor for the MessageRouter class.

Method Summary

Modifier and Type	Method	Description
void	addChannelListener(MessageRouter.StdChannelListener listener)	Adds a given object, implementing the StdChannelListener interface, to the list of standard message channel listeners.
int	countStdChannelListeners()
java.io.PrintWriter	errWriter()
boolean	isRunning()
java.io.PrintWriter	outWriter()
void	removeChannelListener(MessageRouter.StdChannelListener listener)	Removes a given StdChannelListener object from the list of standard channel listeners.
void	run()	Implements the main service method that runs in a separate thread.
void	start()	Starts the main service thread.
void	terminate()	Terminates the main service thread.

Methods inherited from class java.lang.Object

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

Field Detail

OUT_MSG_ID

private static final java.lang.String OUT_MSG_ID

See Also:

Constant Field Values

ERR_MSG_ID

private static final java.lang.String ERR_MSG_ID

See Also:

Constant Field Values

WAITING_TIME

private static final long WAITING_TIME

See Also:

Constant Field Values

_errStream

private java.io.StringWriter _errStream

_errBuffer

private java.lang.StringBuffer _errBuffer

_errWriter

private java.io.PrintWriter _errWriter

_errOffset

private int _errOffset

_outStream

private java.io.StringWriter _outStream

_outBuffer

private java.lang.StringBuffer _outBuffer

_outWriter

private java.io.PrintWriter _outWriter

_outOffset

private int _outOffset

_terminated

private boolean _terminated

_thread

private java.lang.Thread _thread

_stdHistory

private java.util.List<java.lang.String> _stdHistory

_stdListeners

private java.util.List<MessageRouter.StdChannelListener> _stdListeners

Constructor Detail

MessageRouter

public MessageRouter()

Default constructor for the MessageRouter class. This constructor allocates all resources, but does not start the main service thread. Applications should start the MessageRouter thread using the start() method.

Method Detail

addChannelListener

public void addChannelListener(MessageRouter.StdChannelListener listener)

Adds a given object, implementing the StdChannelListener interface, to the list of standard message channel listeners. Sends to the new listener all previously collected messages for this channel.

Parameters:

listener - The given new standard message channel listener.

countStdChannelListeners

public int countStdChannelListeners()

Returns:

Current number of standard channel listeners.

isRunning

public boolean isRunning()

Returns:

true, if the router thread is running, false otherwise.

removeChannelListener

public void removeChannelListener(MessageRouter.StdChannelListener listener)

Removes a given StdChannelListener object from the list of standard channel listeners.

Parameters:

listener - The StdChannelListener object to be removed from the list.

run

public void run()

Implements the main service method that runs in a separate thread.

Specified by:

run in interface java.lang.Runnable

errWriter

public java.io.PrintWriter errWriter()

Returns:

The standard error message channel writer.

outWriter

public java.io.PrintWriter outWriter()

Returns:

The standard output message channel writer.

start

public void start()

Starts the main service thread.

terminate

public void terminate()

Terminates the main service thread.