WebSphere Business Integration Adapters: An Adapter Development and WebSphere Business Integration Solution

292 WebSphere Business Integration Adapters

18.1 Using the pollForEvents() method

The CWConnectorAgent class is the default implementation for the

pollForEvents() method. You can override this method to provide your own

implementation.

Figure 18-1 shows a sequence diagram of the basic login for the

pollForEvents() method.

Figure 18-1 A sequence diagram for the pollForEvents() method

CWConnectorAgent

getEventsStore()

RMEventStore

fetchEvents()

getNextEvent()

eventObj

1. Get the EventStore implementation.

2. Fetch PollQuantity number of events

from the application.

3. Process each event retrieved from

the application. Get the next event to

be processed.

isSubscribed()

4. Check if the connector has subscribed

to the event generated for the business

object.

5. If there is a subscription, build a

business object based on the

information in the event that is retrieved.

getBO(eventObj)

businessObj

gotApplEvent(businessObj)

6. Send the event to the integration

broker.

7. If the event was sent to the connector

framework, archive and delete the

event from the event store.

archiveEvent()

deleteEvent()

Chapter 18. Polling for events 293

Example 18-1 shows the implementation of basic logic for the pollForEvents()

method.

Example 18-1 Default implementation for the pollForEvents() method

/** * Default implementation of pollForEvents. */

public int pollForEvents() {

CWConnectorUtil.traceWrite(

CWConnectorLogAndTrace.LEVEL5,

"Entering pollForEvents.");

// Get the EventStoreFactory implementation name from the

// getEventStore() method.

CWConnectorEventStore evts = getEventStore();

if (evts == null) {

CWConnectorUtil.generateAndLogMsg(

10533,

CWConnectorLogAndTrace.XRD_ERROR,

0,

0);

return CWConnectorConstant.APPRESPONSETIMEOUT }

try {

// Fetch PollQuantity number of events from the application.

try {

evts.fetchEvents();

} catch (StatusChangeFailedException e) {

CWConnectorUtil.generateAndLogMsg(

10533,

CWConnectorLogAndTrace.XRD_ERROR,

0,

0);

CWConnectorUtil.logMsg(e.getMessage());

e.printStackTrace();

return CWConnectorConstant.APPRESPONSETIMEOUT;

}

// Get the property values for PollQuantity and ArchiveProcessed.

int pollQuantity;

String poll = CWConnectorUtil.getConfigProp("PollQuantity");

try {

if (poll == null || poll.equals(""))

pollQuantity = 1;

else

pollQuantity = Integer.parseInt(poll);

} catch (NumberFormatException e) {

CWConnectorUtil.generateAndLogMsg(

Note: For the adapter, use the default implementation because it meets the

needs of the application.

294 WebSphere Business Integration Adapters

10544,

CWConnectorLogAndTrace.XRD_ERROR,

0);

CWConnectorUtil.logMsg(e.getMessage());

e.printStackTrace();

return CWConnectorConstant.FAIL;

}

String arcProcessed = CWConnectorUtil.getConfigProp("ArchiveProcessed");

// In case the ArchiveProcessed property is not set, use true

// as default.

if (arcProcessed == null || arcProcessed.equals(""))

arcProcessed = CWConnectorAttrType.TRUESTRING;

CWConnectorEvent evtObj;

CWConnectorBusObj bo = null;

try {

for (int i = 0; i < pollQuantity; i++) {

// Process each event retrieved from the application.

// Get the next event to be processed.

evtObj = evts.getNextEvent();

// A null return indicates that there were no events with

// READY_FOR_POLL status. Return SUCCESS.

if (evtObj == null) {

CWConnectorUtil.generateAndLogMsg(

10534,

CWConnectorLogAndTrace.XRD_INFO,

0,

0);

return CWConnectorConstant.SUCCEED;

}

// Check if the connector has subscribed to the event

// generated for the business object.

boolean isSub =

isSubscribed(evtObj.getBusObjName(), evtObj.getVerb());

if (isSub) {

// Retrieve the complete CWConnectorBusObj corresponding

// to the object using the getBO method in

// CWConnectorEventStore. This method sets the verb on a

// temporary business object to RetrieveByContent

// and retrieves the corresponding data information to be

// filled in the business object from the application.

try {

bo = evts.getBO(evtObj);

// Terminate flag will be set in the event store when

// the doVerbFor method returns APPRESPONSETIMEOUT in

// getBO.

if (evts.getTerminate())

return CWConnectorConstant.APPRESPONSETIMEOUT;

} catch (AttributeNotFoundException e) {

CWConnectorUtil.generateAndLogMsg(

Chapter 18. Polling for events 295

10536,

CWConnectorLogAndTrace.XRD_ERROR,

0,

2,

"getBO",

"AttributeNotFoundException");

CWConnectorUtil.logMsg(e.getMessage());

e.printStackTrace();

// Update the event status to ERROR_PROCESSING_EVENT

evts.updateEventStatus(

evtObj,

CWConnectorEventStatusConstants

.ERROR_PROCESSING_EVENT);

if (arcProcessed

.equalsIgnoreCase(CWConnectorAttrType.TRUESTRING)) {

// Archive the event in the application’s archive store

evts.archiveEvent(evtObj.getEventID());

// Delete the event from the event store

evts.deleteEvent(evtObj.getEventID());

}

continue;

} catch (SpecNameNotFoundException e) {

CWConnectorUtil.generateAndLogMsg(

10536,

CWConnectorLogAndTrace.XRD_ERROR,

0,

2,

"getBO",

"SpecNameNotFoundException");

CWConnectorUtil.logMsg(e.getMessage());

e.printStackTrace();

// Update the event status to ERROR_PROCESSING_EVENT

evts.updateEventStatus(

evtObj,

CWConnectorEventStatusConstants

.ERROR_PROCESSING_EVENT);

if (arcProcessed

.equalsIgnoreCase(CWConnectorAttrType.TRUESTRING)) {

// Archive the event in the application’s archive store

evts.archiveEvent(evtObj.getEventID());

// Delete the event from the event store

evts.deleteEvent(evtObj.getEventID());

}

continue;

} catch (InvalidVerbException e) {

CWConnectorUtil.generateAndLogMsg(

10536,

CWConnectorLogAndTrace.XRD_ERROR,

0,

296 WebSphere Business Integration Adapters

2,

"getBO",

"InvalidVerbException");

CWConnectorUtil.logMsg(e.getMessage());

e.printStackTrace();

// Update the event status to ERROR_PROCESSING_EVENT

evts.updateEventStatus(

evtObj,

CWConnectorEventStatusConstants

.ERROR_PROCESSING_EVENT);

if (arcProcessed

.equalsIgnoreCase(CWConnectorAttrType.TRUESTRING)) {

// Archive the event in the application’s archive store

evts.archiveEvent(evtObj.getEventID());

// Delete the event from the event store

evts.deleteEvent(evtObj.getEventID());

}

continue;

} catch (WrongAttributeException e) {

CWConnectorUtil.generateAndLogMsg(

10536,

CWConnectorLogAndTrace.XRD_ERROR,

0,

2,

"getBO",

"WrongAttributeException");

CWConnectorUtil.logMsg(e.getMessage());

e.printStackTrace();

// Update the event status to ERROR_PROCESSING_EVENT

evts.updateEventStatus(

evtObj,

CWConnectorEventStatusConstants

.ERROR_PROCESSING_EVENT);

if (arcProcessed

.equalsIgnoreCase(CWConnectorAttrType.TRUESTRING)) {

// Archive the event in the application’s archive store

evts.archiveEvent(evtObj.getEventID());

// Delete the event from the event store

evts.deleteEvent(evtObj.getEventID());

}

continue;

} catch (AttributeValueException e) {

CWConnectorUtil.generateAndLogMsg(

10536,

CWConnectorLogAndTrace.XRD_ERROR,

0,

2,

"getBO",

"AttributeValueException");