cgl.hpsearch.engine
Class TaskSchedulerEngine

java.lang.Object
  cgl.hpsearch.engine.TaskSchedulerEngine

All Implemented Interfaces:

SystemConstants, TimerExpiryListener

public class TaskSchedulerEngine

extends Object

implements SystemConstants, TimerExpiryListener

The task scheduler engine helps to distribute activities to disparate nodes. As each request comes in, it spawns off a new RequestHandler.
The RequestHandler then reads the request and starts the appropriate Handler.

Author:

Harshawardhan Gadgil

See Also:

RequestHandler, Handler

Field Summary

Fields inherited from interface cgl.hpsearch.common.SystemConstants

ABANDON_HANDLER, ABANDONED, BROKER_HOST, BROKER_PORT, BUF_SIZE, EOT, EXCEPTION, FAILURE, FILESEPARTOR, FLOW_LOGGING_MANAGER, FLOW_MANAGER, HPSEARCH_CONFIG, HPSEARCH_HOME, HPSEARCH_SHELL, HPSEARCH_WS, MARKER, NB_HOME, NB_PERFORMANCE_DATA_TOPIC, OS_TYPE, OS_UNIX, OS_WIN, PORT, PROTOCOL, READY, RESUME, RUNNING, SCRIPT_ARGS, SCRIPT_PATH, SHELLWS_PORT, START_HANDLER, STREAM_MARKER_DATA, STREAM_MARKER_EOF, STX, SUCCESS, SUSPEND, TASK_DEFINED, TASK_SCHEDULER_ENGINE, TASKSCHEDULER_AUTO_CONNECT_COMM_LINK, TASKSCHEDULER_ENGINE_COMM_LINK, THREAD_SLEEP_INTERVAL, UNKNOWN, WAITING, WSCONTEXT_RESULT_BIN, WSCONTEXT_SERVICE

Constructor Summary

TaskSchedulerEngine()
Initializes a TaskSchedulerEngine.

Method Summary

String	getEngine(int engine) Returns the id of the best possible engine to run this particular task
int	getFlowStatus(String flowID) Returns the status of the specified flow
void	handlerFinished(RequestHandler rh) Called by the RequestHandlers to tell the TaskSchedulerEngine that it is done with the task assigned to it.
void	onTimerExpiry(Object o) If a timer expires for a particular engine we just assume the engine to be dead.
void	processEvent(Object o) Processes an event sent from another engine to this engine...
TaskHandler	processFlowRequest(Vector flowComponents, String flowID) Creates a new TaskHandler that handles the flow specified by the flowComponents
void	requestHandlerRegistered(RequestHandler rh) Requests the TaskSchedulerengine to register the init stage of te RequestHandler.
void	sendEventMessage(HandlerEvent msg, RequestHandler _rh) Sends the Event message to the specified Engine
void	sendTaskSchedulerEvent(String event) Sends the command to the Engine running on another node.
void	startEngine() Initializes the TaskScheduler engine instance.
void	stopEngine() Stops the TaskScheduler engine. sends the "GOODBYE" event to all engines to signify graceful shutdown
boolean	tryInitCOMMLink(String h, int p, String prot) Tries to initialize the communication link to a broker using the protocol specified as defined by the following parameters
void	waitForFlowToStart(String flowID) Waits for the specified flow to start

Methods inherited from class java.lang.Object

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

Constructor Detail

TaskSchedulerEngine

public TaskSchedulerEngine()

Initializes a TaskSchedulerEngine. Must explicitly call the ServerStart to connect the Engine to a broker and start listening on a particular stream.

Method Detail

startEngine

public void startEngine()

Initializes the TaskScheduler engine instance.

tryInitCOMMLink

public boolean tryInitCOMMLink(String h,
                               int p,
                               String prot)

Tries to initialize the communication link to a broker using the protocol specified as defined by the following parameters

Parameters:

h - - Host of the broker

p - - Port to which connection must be tried

prot - - Protocol to use

Returns:

TRUE if connection was successful, FALSE otherwise

stopEngine

public void stopEngine()

Stops the TaskScheduler engine. sends the "GOODBYE" event to all engines to signify graceful shutdown

processEvent

public void processEvent(Object o)

Processes an event sent from another engine to this engine...

Parameters:

o - Object representing the event

Returns:

Nothing.

requestHandlerRegistered

public void requestHandlerRegistered(RequestHandler rh)

Requests the TaskSchedulerengine to register the init stage of te RequestHandler. The TaskSchedulerEngine then creates a TSE event to notify the init to the requesting engine

Parameters:

rh - - The RequestHandler

onTimerExpiry

public void onTimerExpiry(Object o)

If a timer expires for a particular engine we just assume the engine to be dead.
Protocol to be followed:
The heartbeat is sent every 30 seconds while the timer is set to expire evry minute. We allow for extra 30 seconds for the heartbeat to reach the engine. If a heartbeat does not reach withing 1 minute, we assume the engine dead

Specified by:

onTimerExpiry in interface TimerExpiryListener

processFlowRequest

public TaskHandler processFlowRequest(Vector flowComponents,
                                      String flowID)

Creates a new TaskHandler that handles the flow specified by the flowComponents

Parameters:

flowComponents - The components of the flow

flowID - The unique flow ID

Returns:

TaskHandler

waitForFlowToStart

public void waitForFlowToStart(String flowID)

Waits for the specified flow to start

Parameters:

flowID - - The ID representing the flowHandler in question

getFlowStatus

public int getFlowStatus(String flowID)

Returns the status of the specified flow

Parameters:

flowID - - the UUID of the flow

Returns:

The flow status

handlerFinished

public void handlerFinished(RequestHandler rh)

Called by the RequestHandlers to tell the TaskSchedulerEngine that it is done with the task assigned to it. The TaskSchedulerEngine then sends out a EngineEvent notifying the others.

sendEventMessage

public void sendEventMessage(HandlerEvent msg,
                             RequestHandler _rh)

Sends the Event message to the specified Engine

Parameters:

msg - - The message to be sent

sendTaskSchedulerEvent

public void sendTaskSchedulerEvent(String event)

Sends the command to the Engine running on another node.

Parameters:

event - event as an XML string

getEngine

public String getEngine(int engine)

Returns the id of the best possible engine to run this particular task

Returns:

String representing the id of the engine