I do a university course on business process management. The lecturer said that you can model conditions on sequence flows, which I agree with. However in the context of gateways he said that you can even model conditions on outgoing sequence flows if you use parallel gateways. My understanding is that this is not correct as the bpmn specification/page 97 also states:
A Sequence Flow can optionally define a condition Expression, indicating that the token will be passed down the Sequence Flow only if the Expression evaluates to true. This Expression is typically used when the source of the Sequence Flow is a Gateway or an Activity.
- A conditional outgoing Sequence Flow from an Activity MUST be drawn with a mini-diamond marker at the beginning of the connector (as seen in Figure 8.33).
- If a conditional Sequence Flow is used from a source Activity, then there MUST be at least one other outgoing Sequence Flow from that Activity.
- Conditional outgoing Sequence Flows from a Gateway MUST NOT be drawn with a mini-diamond marker at the beginning of the connector.
- A source Gateway MUST NOT be of type Parallel or Event.
From my interpretation the last 2 list items explicitly forbid to model conditions on outgoing sequence flows of a parallel gateway. Am I right or wrong? Or is this more a question of definition and modelling philosophy?
Thank you in advance
I think you are correct with your interpretation of the specification. Here is another source that also states that parallel gateways cannot have conditions.
That being said, in practice you will sometimes find diagrams that violate the standard in a detail. If the diagram is still very clear and understandable, I am personally okay with that - after all, diagrams are meant to be a tool for communication. But you will find other people who would not share this opinion. So yes, asking for the modelling philosophy is also a valid question.
On this concrete example, I do not really see a purpose of having parallel paths with conditions.