stella.net

Class CasterClient.CommandSender

java.lang.Object

java.lang.Thread

stella.net.CasterClient.CommandSender

All Implemented Interfaces:

Runnable, AlarmHandler

Enclosing class:

CasterClient

protected class CasterClient.CommandSender
extends Thread
implements AlarmHandler

The helper thread for this ascii caster to handle a command/acknowledge/done sequence. This thread is started after the connection to the command receiver (server) has been established. To allow the main thread to return-fast from its CasterClient.castCommand(stella.CommandEvent) method this helper thread does the whole handling of writing the command to the socket as an ASCII-String, waiting for the acknowledge and done replies and call time-out handlers if necessary.

Please not that any command sent to the server must be terminated with a final done regardless of errors occuring or further commands sent during the processing of the actual command!

To avoid time-consuming construction of lookup-tables for each command sent this class uses static lookup-tables that are constructed only once.

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

Thread.State, Thread.UncaughtExceptionHandler

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	cancel Gets true if this thread should terminate unexpectedly.
private CommandEvent	command The command to send to the server.
private static String	COMPLETE The name for alarms waiting for done or additional acknowledges.
private static String	FIRSTACKNOWLEDGE The name for alarms waiting for the first acknowledge.

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	CommandSender(ThreadGroup group, CommandEvent cmd) Constructs a new command sender.

Method Summary

Modifier and Type	Method and Description
void	cancel() Cancels the current cycle.
void	run() The main method of the command sender.
void	setOff(String alarm) The method called by the internal alarms of this caster if a problem with in-time replies occured.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Field Detail

command

private CommandEvent command

The command to send to the server.

cancel

private boolean cancel

Gets true if this thread should terminate unexpectedly.

FIRSTACKNOWLEDGE

private static final String FIRSTACKNOWLEDGE

The name for alarms waiting for the first acknowledge.

See Also:

Constant Field Values

COMPLETE

private static final String COMPLETE

The name for alarms waiting for done or additional acknowledges.

See Also:

Constant Field Values

Constructor Detail

CommandSender

protected CommandSender(ThreadGroup group,
                        CommandEvent cmd)

Constructs a new command sender. The command and the thread group the sender should run in are given as arguments. The socket connection handed over is already opened by the calling class, but is automatically closed after the command-specific done has been received.

This thread is not started automatically.
Note that construction may be blocked if the server is not accepting connetions, see CasterClient.KEY_RETRYCOUNT and CasterClient.KEY_RETRYSLEEP.

Method Detail

cancel

public void cancel()

Cancels the current cycle. Note that all alarms are left unhandled.

run

public void run()

The main method of the command sender. If no error occurs this method does the following:

• Writes the command to the out-stream of the socket.
• Starts an alarm thread with the acknowledge time-out.
• Registers the alarm on the alarm table. If the alarm table already contains an alarm linked to the key a software error is cast (type 809).
• Reads the socket's in-stream for incoming done/acknowledge events.
• Starts and cancels alarms accordingly.
• Notifies reply listeners if a received reply matches the posted request (parent class method).
• Time-outs of the various alarms are directly handled by the parent class.
• If the final done event is received this thread closes the socket connection to the server and exits.

Note that from the chain of command it is never possible that there is already an alarm mapped to the command's key. If this situation occurs nevertheless this is a software bug and is reported by casting a software error.

Specified by:

run in interface Runnable

Overrides:

run in class Thread

setOff

public void setOff(String alarm)

The method called by the internal alarms of this caster if a problem with in-time replies occured. The name of the alarm is used to either generate a acknowledge time-out error or a completion time-out error. An acknowledge time-out means that the listener did not sent back the acknowledge following the command. This error probably suggests some connection problem since no other action than simply replying to the command is involved. Completion time-outs may indicate that there is a problem with the hardware involved in completing the required task.
Note that acknowledge events sent after the verry first produce completion time-outs rather than acknowledge time-outs.

Specified by:

setOff in interface AlarmHandler