Default Event Error Process (Oracle Workflow Developer's Guide)

Oracle Workflow Developer's Guide
Release 2.6.3.5
Part Number B12161-02


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Default Event Error Process

DEFAULT_EVENT_ERROR is the internal name of the Default Event Error Process for the Business Event System. The purpose of this error handling process is to:

send an administrator a notification when an error or warning condition occurs during event subscription processing

provide information to the administrator about the error

allow the administrator to abort or retry the event subscription processing

'Receive Errored Queue Message' Event Activity

The Receive Errored Queue Message activity receives an event message that has encountered an error or warning condition during subscription processing. For instance, if a subscription rule function returns an ERROR or WARNING status code, or if an unexpected event is received, the Event Manager executes default subscriptions that send the event message to the Default Event Error process. See: Predefined Workflow Events.

The Receive Errored Queue Message activity stores the event name, event key, and the complete event message in item type attributes.

'Initialize Event Error' Function Activity

The Initialize Error activity calls a PL/SQL procedure named WF_STANDARD.INITIALIZEEVENTERROR. This procedure determines the error type.

Event Warning--A warning condition occurred, but subscription processing continued. For this error type, the Workflow Engine sends the Event Warning Notification.

External Event Error--An error occurred to halt subscription processing for an event received from an external source. For this error type, the Workflow Engine sends the External Event Error Notification.

Local Event Error--An error occurred to halt subscription processing for an event raised on the local system. For this error type, the Workflow Engine sends the Local Event Error Notification.

'Event Warning Notification' Activity

The Workflow Engine initiates the Event Warning Notification activity when the errored event has an error type of Event Warning. The activity sends the Default Event Warning message to the system administrator to indicate that a warning condition has occurred during subscription processing. This message is an FYI message and does not require a response.

The subject and body of the Default Event Warning message are as follows:

Subject: Event WARNING : &EVENT_NAME / &EVENT_KEY

Body: A Warning occurred in the following Event 

	Subscription: &EVENT_SUBSCRIPTION

	

	Event Error Name: &ERROR_NAME

	Event Error Message: &ERROR_MESSAGE

	Event Error Stack: &ERROR_STACK

	

	Event Data: &EVENT_DATA_URL

	

	Other Event Details: &EVENT_DETAILS

'External Event Error Notification' Activity

The Workflow Engine initiates the External Event Error Notification activity when the errored event has an error type of External Event Error. The activity sends the Default External Event Error message to the system administrator. This message indicates that an error has occurred during subscription processing for an event received from an external source, and that a response is needed. The response options and their resulting actions are:

Abort--aborts subscription processing and ends the Default Event Error process. For example, if the event data contained in an event message is corrupted, the system administrator can abort subscription processing on that event message.

Enqueue Event--executes the Retry Process Event activity to enqueue the event message back onto the queue where it was originally received, and ends the Default Event Error process. The event message is enqueued with a priority of -1 so that it will be the first message to be dequeued the next time the listener runs.

The system administrator can attempt to correct the error before re-enqueuing the event. For example, the system administrator can create a subscription to handle an unexpected event and then re-enqueue the event message to trigger the new subscription.

The subject and body of the Default External Event Error message are as follows:

Subject: External Event &ERROR_TYPE : &EVENT_NAME / &EVENT_KEY

Body: An Error occurred in the following Event 

	Subscription: &EVENT_SUBSCRIPTION

	

	Event Error Name: &ERROR_NAME

	Event Error Message: &ERROR_MESSAGE

	Event Error Stack: &ERROR_STACK

	

	Event Data: &EVENT_DATA_URL

	

	Other Event Details: &EVENT_DETAILS

'Local Event Error Notification' Activity

The Workflow Engine initiates the Local Event Error Notification activity when the errored event has an error type of Local Event Error. The activity sends the Default Local Event Error message to the system administrator. This message indicates that an error has occurred during subscription processing for an event raised on the local system, and that a response is needed. The response options and their resulting actions are:

Abort--aborts subscription processing and ends the Default Event Error process.

Raise Event with Event Key--executes the Retry Process Event activity to reraise the event with only the event name and event key, and ends the Default Event Error process.

Raise Event with Event Key and Event Data--executes the Retry Process Event activity to reraise the event with only the event name, event key, and event data, and ends the Default Event Error process.

Raise Event with Event Key, Event Data and Parameters-- executes the Retry Process Event activity to reraise the event with the event name, event key, event data, and parameters, and ends the Default Event Error process.

The system administrator can choose the level of information to provide to the Event Manager when reraising the event. For example, if an error exists in the event data that was originally provided, the event can be reraised with only the event name and the event key, forcing the Event Manager to regenerate the event data using the event's Generate function.

The system administrator can also attempt to correct the error before reraising the event.

The subject and body of the Default Local Event Error message are as follows:

Subject: Local Event &ERROR_TYPE : &EVENT_NAME / &EVENT_KEY

Body: An Error occurred in the following Event 

	Subscription: &EVENT_SUBSCRIPTION

	

	Event Error Name: &ERROR_NAME

	Event Error Message: &ERROR_MESSAGE

	Event Error Stack: &ERROR_STACK

	

	Event Data: &EVENT_DATA_URL

	

	Other Event Details: &EVENT_DETAILS

'Retry Process Event' Function Activity

The Retry Process Event activity executes the PL/SQL procedure WF_STANDARD.RETRYRAISE. Depending on the notification response selected by the system administrator, this procedure either re-enqueues or reraises an errored event. The responses that can initiate the Retry Process Event activity and their resulting actions are:

Enqueue Event--enqueues an errored external event message back onto the queue where it was originally received. The event message is enqueued with a priority of -1 so that it will be the first message to be dequeued the next time the listener runs.

Raise Event with Event Key--reraises a local errored event with only the event name and event key.

Raise Event with Event Key and Event Data--reraises a local errored event with only the event name, event key, and event data.

Raise Event with Event Key, Event Data and Parameters-- reraises a local errored event with the event name, event key, event data, and parameters.