com.bea.adapter.event
Class AbstractPullEventGenerator

java.lang.Object
  com.bea.adapter.event.AbstractEventGenerator
      com.bea.adapter.event.AbstractPullEventGenerator

All Implemented Interfaces:

IEventGenerator, Runnable

Direct Known Subclasses:

AbstractBEAPullEventGenerator

public abstract class AbstractPullEventGenerator

extends AbstractEventGenerator

implements Runnable

A class that does work for an event generator. Adapter providers can override methods on this class to provide EIS specific event generation logic.

NOTE: This class implements the methods needed to support the ISuspendableEventGenerator interface. This class does NOT, however, implement ISuspendableEventGenerator. The decision to implement or not is left to the subclasses of this class. However, if a subclass does decide to implement ISuspendableEventGenerator, they can simply delegate the calls on this interface to 'super'.

Author:

Copyright (c) 1998-2000 by BEA Systems, Inc. All Rights Reserved.

Field Summary

Fields inherited from class com.bea.adapter.event.AbstractEventGenerator

m_setOfEventTypes

Constructor Summary

AbstractPullEventGenerator()

Method Summary

protected void	checkInitializeState() Checks initialization state of PullEventGenerator
protected void	checkThreadState() Checks the thread state of the PullEventGenerator
protected void	doCleanUpOnQuit() Performs any clean-up needed once this object determines that it is time to quit running.
protected void	doInit(Map map) Performs EIS specific initialization of this object based on properties in the map argument.
boolean	isSuspended() Indicates if this thread is in the suspended state.
protected abstract void	postEvents(IEventRouter router) Posts EIS events to the event router.
protected abstract void	removeDeadTypes(List listOfDeadTypes) Allows this instance to apply any EIS specific setup logic needed to handle dead event types; an event type is considered dead if it is no longer in the list of event types known to the router.
void	resume() Resume the generation of events.
void	run() Runnable implementation.
protected abstract void	setupNewTypes(List listOfNewTypes) Allows this instance to apply any EIS specific setup logic needed to handle new event types provided by the event router.
void	start() Starts the PullEventGenerator to polling.
void	stop() Notifies this thread that it should stop posting events to the event router.
void	suspend() Suspend (temporarily) the generation of events.

Methods inherited from class com.bea.adapter.event.AbstractEventGenerator

assertValidLicense, checkLicense, createSetOfEventTypes, getEventDefinition, getEventTypes, getInitializationParms, getLogContext, getLogger, getRouter, getSleepCount, handlePostEventException, init, isEventTypeKnownToRouter, isInitialized, logDeadTypes, logEventTypes, logNewTypes, logPostEventException, refresh

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractPullEventGenerator

public AbstractPullEventGenerator()

Method Detail

doInit

protected void doInit(Map map)
               throws Exception

Performs EIS specific initialization of this object based on properties in the map argument. Adapter developers must override this method according to their EIS specific needs.

Specified by:

doInit in class AbstractEventGenerator

Throws:

Exception - - an exceptional condition was encountered while attempting to initialize this object based on properties in the map; perhaps the map is missing a required parameter.

checkInitializeState

protected void checkInitializeState()
                             throws Exception

Checks initialization state of PullEventGenerator

Throws:

Exception

checkThreadState

protected void checkThreadState()
                         throws Exception

Checks the thread state of the PullEventGenerator

Throws:

Exception

doCleanUpOnQuit

protected void doCleanUpOnQuit()
                        throws Exception

Performs any clean-up needed once this object determines that it is time to quit running. Adapter developers should override this method to free any resources held by this instance.

Specified by:

doCleanUpOnQuit in class AbstractEventGenerator

Throws:

Exception - - an exceptional condition was encountered while attempting to clean-up resources used by this instance.

postEvents

protected abstract void postEvents(IEventRouter router)
                            throws Exception

Posts EIS events to the event router. Adapter developer's should call isEventTypeKnownToRouter before processing an event because this worker should not waste computing cycles on generating events that the router does not care about. For implementations that can post multiple events from a single call to postEvents, they should periodically check the value of isSuspended and return in a timely fashion when it returns true. This method is invoked in a block of code that is synchronized around the set of event types maintained by this instance. Thus, any concurrent calls to the refresh from another thread will need to wait until this method returns.

 Iterator i = getEventTypes();
 while (i.hasNext())
 {
   String strEventType = (String)i.next();
   IEventDefinition eventDef = new EventDefinition();
   eventDef.setName(strEventType);
   IEvent event =
     new Event("<" + strEventType + ">bogus");
   event.setEventDefinition(eventDef);

   try
   {
     m_router.postEvent(event);
   }
   catch (Exception exc)
   {
     handlePostEventException(event, exc);
   } // end try/catch
 } // end while
 

Throws:

Exception

suspend

public void suspend()
             throws Exception

Suspend (temporarily) the generation of events. Any events that occur on the EIS instance must be preserved either on the EIS instance itself, or within some EventGenerator-specific store. This call will allow any active call to postEvents to return before it itself returns.

Throws:

Exception

resume

public void resume()
            throws Exception

Resume the generation of events. Any events that have occurred while this EventGenerator was suspended, should now be delivered as soon as possible to the EventRouter.

Throws:

Exception

isSuspended

public boolean isSuspended()

Indicates if this thread is in the suspended state. If this method returns true, no calls will be made to postEvents, though current calls to postEvents are allowed to complete. Subclasses should periodically check the return value of this method, and return from postEvents in a timely fashion when it returns true.

run

public void run()

Runnable implementation. Used to log and route events to the concrete implementation.

Specified by:

run in interface Runnable

start

public void start()
           throws Exception

Starts the PullEventGenerator to polling.

Specified by:

start in interface IEventGenerator

Specified by:

start in class AbstractEventGenerator

Throws:

Exception

stop

public void stop()
          throws Exception

Notifies this thread that it should stop posting events to the event router.

Specified by:

stop in interface IEventGenerator

Specified by:

stop in class AbstractEventGenerator

Throws:

Exception

setupNewTypes

protected abstract void setupNewTypes(List listOfNewTypes)
                               throws Exception

Allows this instance to apply any EIS specific setup logic needed to handle new event types provided by the event router.

Specified by:

setupNewTypes in class AbstractEventGenerator

Parameters:

listOfNewTypes - - a list of new types (IEventDefinition objects)that were not in the set of event types maintained by this instance prior to the refresh.

Throws:

Exception

removeDeadTypes

protected abstract void removeDeadTypes(List listOfDeadTypes)
                                 throws Exception

Allows this instance to apply any EIS specific setup logic needed to handle dead event types; an event type is considered dead if it is no longer in the list of event types known to the router.

Specified by:

removeDeadTypes in class AbstractEventGenerator

Parameters:

listOfDeadTypes - - a list of event types (IEventDefinition objects) that were not in the list of event types provided by the router and were in the set maintained by this instance prior to the refresh.

Throws:

Exception