Trigger

Understand how WorldVisa processes a trigger event from initial API request to fan-out, digest, delay, and channel delivery inside a workflow run.

Trigger Request

A trigger request is the initial step in handling a trigger event. It contains crucial details such as the template identifier, a list of subscribers who will receive the notification, the payload of the notification, and any overrides that need to be applied.

Trigger Endpoint

Upon sending the request to the event/trigger endpoint, a series of essential steps are initiated:

1. Subscriber Mapping and Validation: The first step involves mapping and validating the subscribers for the specified event. This ensures that notifications are sent to the correct recipients.

2. Workflow Validation: Following subscriber validation, the workflow associated with the event is validated. This validation process considers factors such as the active status to determine if it meets the necessary criteria for processing.

3. Attachment Upload: Once the validation process is successfully completed, any attachments associated with the event are uploaded to the designated storage service.

4. Event Queuing: The trigger event, now enriched with mapped subscribers and attachment links, is appended to the trigger event queue. This queuing mechanism optimizes response times, ensuring efficient event processing.

Trigger Event Processing

When an event is picked up by the trigger queue worker, the processing phase begins. Here’s what happens:

• Subscriber Upsert: The worker validates the subscribers associated with the event and either creates or updates the subscriber with the information passed in the to object.
• Context Upsert: When the trigger includes context entries with inline data objects, the worker creates missing contexts or replaces existing context data. String-only context references do not modify stored data. Inbox and other subscriber-facing APIs do not perform context data updates.
• Notification Entity Creation: For each subscriber listed in the trigger event, a corresponding notification entity is created. This entity contains essential data related to the organization, template, subscriber, and event payload.
• Job Creation: Based on the notification template’s defined steps, jobs are generated. These jobs are responsible for carrying out specific tasks related to the event notification. Additionally, the notification entity is updated with a “channels” field generated from these steps, indicating the communication channels through which notifications will be sent.

Jobs

Jobs play a crucial role in the trigger event lifecycle. They are created based on the steps outlined in the workflow.

Job Statuses

Status	Description
PENDING	This status is assigned to a job before it is added to the worker queue. It indicates that the job is waiting to be processed.
QUEUED	After the initial validation and just before adding a job to the worker queue, it is set to QUEUED. This status signifies that the job is ready for processing but is awaiting its turn in the queue.
RUNNING	When a job is picked up by a worker from the queue, its status is changed to RUNNING. This indicates that the job is currently being processed by a worker.
COMPLETED	Once a job has been successfully executed and processed, its status is changed to COMPLETED. This signifies that the job has been successfully completed.
FAILED	If a job encounters an issue during processing or execution, its status is changed to FAILED. This indicates that the job has not been successfully completed, and there may have been errors or problems during processing.
DELAYED	The DELAYED status is applied to specific types of jobs, such as digest or delay jobs, to indicate that they are delayed and not immediately processed. For digest jobs, it means that the digesting process is running or scheduled for a later time. For delay jobs, it signifies that the job is set to be executed at a specified delay time.
CANCELED	When a job is canceled for any reason, its status is set to CANCELED. This indicates that the job will not be processed further and is effectively removed from the processing queue.
MERGED	The MERGED status is assigned to events that are part of a digest. It indicates that an event will be merged into the digesting event. In a digesting process, there is typically a primary or initial event that serves as the digesting event, and subsequent events are merged into it. Instead of having a separate COMPLETED status for these merged events, they are marked as MERGED to indicate their specific role in the digesting process.
SKIPPED	The SKIPPED status is used in the context of backoff versions of digesting. In this scenario, the first event’s digesting is skipped, and the second event takes on the digesting role. The SKIPPED status is applied to the first event’s digesting, indicating that it was intentionally skipped in the digesting process. Subsequent events may be merged into the second event’s digesting process, as explained with the MERGED status. The SKIPPED status helps differentiate the skipped event from others in the digesting sequence.

Follow a trigger through delivery

The trigger response confirms that the event was accepted. It does not confirm that a provider delivered the message. Open the Activity Feed to inspect each step and its result. Keep the returned transaction ID when investigating a particular request.