Event Activity
An event activity represents a business event from the Business Event System within a workflow process. Include event activities in workflow processes to model complex processing or routing logic for business events beyond the standard event subscription options of running a function or sending the event to a predefined agent. See: Managing Business Events.
An event activity can either receive, raise, or send a business event.
- A Receive event activity can be marked as a Start activity for a process, meaning it is always enabled to receive events. Alternatively, a Receive event activity can be placed within the process, so that it is only enabled to receive events after the process transitions to that activity.
When the activity receives an event, the Workflow Engine stores the event name, event key, and event message in item type attributes, as specified in the node's event details, and then continues the thread of execution from the event activity. If that activity has already received an event, then the On Revisit flag for the activity determines whether the Workflow Engine reexecutes the activity. See: To Define Optional Activity Details.
If the event was originally raised by a Raise event activity in another workflow process, the item type and item key for that process are included in the parameter list within the event message. In this case, the Workflow Engine automatically sets the specified process as the parent for the process that receives the event, overriding any existing parent setting. See: SetItemParent.
- A Raise event activity retrieves information about the event and raises the event to the Business Event System, which will then execute subscriptions to the event. The activity retrieves the event name, event key, and event data as specified in the node's event details. The event details can be dynamically determined at runtime using item type attributes. You can also specify the event name as a predefined constant for the event activity node.
Additionally, the activity retrieves the names and values of any activity attributes defined for it and sets these attributes as parameters in the parameter list for the event message. See: Event Message Structure.
The activity also automatically sets the item type and item key for the current workflow process in the parameter list for the event message. If the event message is later received by another process, the Workflow Engine uses that item type and item key to automatically set the process that raised the event as the parent for the process that receives the event. See: SetItemParent.
- A Send event activity retrieves the event name, event key, event message, outbound agent, and inbound agent, as specified in the node's event details. If no correlation ID is initially specified in the event message, the correlation ID is automatically set to the item key of the process. Then the Send event activity sends the event directly from the outbound agent to the inbound agent. The event details can be dynamically determined at runtime using item type attributes. You can also specify the event name, outbound agent, and inbound agent as predefined constants for the event activity node. See: To Create an Event Activity and To Define Event Details for an Event Node.
Note: A Send event activity does not raise the event to the Business Event System, so no subscription processing is performed.
