An event is a message that notifies other components about a change of state, an action or an occurred fact. Event Trigger responds to a specific event generated by another pipeline through Event Publisher. To read about this component, click here.

More information about Event-Oriented Architecture can be found here.

Take a look at the configuration parameters of the trigger:

  • Event Name: name of the event the trigger responds to.
  • Expiration: time the event spends in the queue (in milliseconds). If the expiration is = 0 or a value greater than 6h, then the expiration will be 1/4 of the specified Maximum timeout value.
  • Maximum Timeout: maximum execution time of the pipeline initiated by Event Trigger (in milliseconds).
  • Allow Redelivery of Messages: if activated, the option allows messages to be delivered again if the Pipeline Engine fails.

Messages flow

Input

The trigger expects a valid message in JSON format. The received message is exactly the one define in the body attribute of the Event Publisher component.

{
"id": "1",
"description": "Description of the case"
}

Output

The component repasses the received message of the previous component with no changes. In the example above, the repassed message would be:

{
"id": "1",
"description": "Description of the case"
}

Event Trigger in Action

To implement an Event-Oriented Architecture, it's necessary to define:

  • the pipeline to publish the event (Publisher)
  • one or more pipelines to consume the event (Subscribers)

To configure the pipeline to publish the event:

  • drag the Event Publisher to the Publisher pipeline canvas;
  • configure the name of the event in the "Event" property of Event Publisher;
  • if you want to define a payload with the event, then define the content in the “Body” property.

To configure the pipeline to consume the event:

  • change the trigger type to Event in the Subscriber pipeline;
  • open the trigger configurations and inform the name of the event to be consumed in the "Name of the Event" property. This value must be identical to the one informed in the Event Publisher of the Publisher pipeline.
Did this answer your question?