Process lifecycles

In Zeebe, the process execution is represented internally by events of type ProcessInstance. The events are written to the log stream and can be observed by an exporter.

Each event is one step in a process instance lifecycle. All events of one process instance have the same processInstanceKey.

Events which belongs to the same element instance (e.g. a task) have the same key. The element instances have different lifecycles depending on the type of element.

(Sub-)Process/Activity/Gateway lifecycle

Event lifecycle

Sequence flow lifecycle

Example

Given the above process a successful execution will yield the following records in the commit log:

Intent	Element id	Element type
ELEMENT_ACTIVATING	order-process	process
ELEMENT_ACTIVATED	order-process	process
ELEMENT_ACTIVATING	order-placed	start event
ELEMENT_ACTIVATED	order-placed	start event
ELEMENT_COMPLETING	order-placed	start event
ELEMENT_COMPLETED	order-placed	start event
SEQUENCE_FLOW_TAKEN	to-collect-money	sequence flow
ELEMENT_ACTIVATING	collect-money	task
ELEMENT_ACTIVATED	collect-money	task
ELEMENT_COMPLETING	collect-money	task
ELEMENT_COMPLETED	collect-money	task
SEQUENCE_FLOW_TAKEN	to-fetch-items	sequence flow
...	...	...
SEQUENCE_FLOW_TAKEN	to-order-delivered	sequence flow
EVENT_ACTIVATING	order-delivered	end event
EVENT_ACTIVATED	order-delivered	end event
ELEMENT_COMPLETING	order-delivered	end event
ELEMENT_COMPLETED	order-delivered	end event
ELEMENT_COMPLETING	order-process	process
ELEMENT_COMPLETED	order-process	process