BPMN Conditional Event

in BPMN on Bpmn, Bpmn 2.0, Conditional event
BPMN Conditional Event

The BPMN Conditional Event article provides a detailed explanation of the conditional event element, including the BPMN notation, an example diagram and guidelines.

The BPMN Conditional Event article focus on the definition and usage of the conditional event element as documented in the BPMN 2.0 specification. The example process diagram illustrates the correct use of the conditional event annotation. The BPMN Guidelines section contains a detailed set of rules that apply to the conditional event and explains how the element may or may not be used within the different BPMN diagrams.

What is a Conditional Event?

“Conditional triggers are implicitly thrown. When they are activated they wait for a status based condition respectively to trigger the catch Event. This type of event is triggered when a condition become true.” ~ BPMN Specification

BPMN Notation

The BPMN specification defines the Conditional Event element using the following description and notation:

Catching EventsThrowing Events
Start EventIntermediate EventEnd Event
StandardEvent Sub-Process
Interrupting		Event Sub-Process
Non-Interrupting		CatchingBoundary
Interrupting		Boundary Non-
Interrupting		ThrowingStandard
Conditional Event

BPMN Notation: Conditional Event

BPMN Event Types

The following table contains a list of the different Conditional Event types, their descriptions and the BPMN notations:

ElementDescriptionNotation
Conditional Start EventThis type of Event is triggered when a condition (a type of Expression) becomes true. Whenever the Event occurs, a new process instance is started.
Conditional Event Sub-Process Event (Interrupting)This type of Event is triggered when a condition (a type of Expression) becomes true. Whenever the Event occurs, execution of the enclosing Sub-Process is cancelled and the Event Sub-Process continues execution.
Conditional Event Sub-process Event (Non-Interrupting)This type of Event is triggered when a condition (a type of Expression) becomes true. Whenever the Event occurs, execution of the enclosing Sub-Process continues in parallel to the Event Sub-Process.
Conditional Intermediate Catch EventThis type of Event is triggered when a condition (a type of Expression) becomes true. Whenever the Event occurs, the event allows the process to continue.
Conditional Boundary Event (Interrupting)This type of Event is triggered when a condition (a type of Expression) becomes true. Whenever the event occurs, the associated Activity is terminated. A downstream token is then generated, which activates the next element of the Process.
Conditional Boundary Event (Non-Interrupting)This type of Event is triggered when a condition (a type of Expression) becomes true. Whenever the Event occurs, the associated Activity continues to be active. As a token is generated for the Sequence Flow from the boundary Event in parallel to the continuing execution of the Activity.

BPMN Event Types: Conditional Events

BPMN Diagram

The following is an example of a BPMN Conditional Event within a diagram:

BPMN Conditional Event Example of BPMN Conditional Event

BPMN Standards & Guidelines

The difference between standard and guideline is that a standard is a level of quality or attainment while a guideline is a non-specific rule or principle that provides direction to action or behaviour. A standard are high in authority and needs to be adhered to versus a guideline is low in authority and guide one in setting standards or determining a course of action.

BPMN Standards

The BPMN Standards section contains a list of rules that are applicable to the BPMN Conditional Event as per the official rules of the BPMN Specification.

  • The condition Expression for the Event MUST become false and then true before the Event can be triggered again.
  • The condition Expression of a Conditional Start Event MUST NOT refer to the data context or instance attribute of the Process (as the Process instance has not yet been created).
  • The condition Expression of a Conditional Start Event MAY refer to static Process attributes and states of entities in the environment.

BPMN Guidelines

The BPMN guidelines section contains a list of optional rules that can be used as a guide.

  • A Conditional Start Event should have a Text Annotation describing the condition that would trigger the event.

Finally

This article provided a detailed explanation of the BPMN Conditional Event element. Follow me on any of the different social media platforms, and feel free to leave comments.

Reference