Why do we need BPD and BPMN?

[Jane Somerfield]

I used a lot of Activity Diagrams of UML. I did not see anything in Business Process Diagram (BPD) that Activity Diagram can not do.

[Peer Reynders]

I think that it is a matter of target audience. UML stands for "Unified Modeling Langauge" - the "U" doesn't stand for "Universal" (if it did, it would be lying). There have been many claims that UML can be used to communicate with the business owners and domain experts. However UML was developed by people who designed, built and coded object-oriented systems - and ultimately UML was shaped by that perspective. UML is most effective when it is used to sketch out pertinent aspects of a system - as long as the communicating parties are involved with technical aspects of the system. When communicating with business owners and domain experts who lack a OO software development background it is usually easier to ditch UML and use ad hoc "blocks and arrows".

However these ad hoc notations aren't toolable. So Business Process Diagrams were developed as a generic means to represent "Business Processes" to non-technical stakeholders with the ultimate goal of manipulating the actual Business Processes through manipulation of the representations. (The tooling of that notation ultimately creates the risk of the "technical" aspects leaking back into the notation which in turn could alienate its intended audience.)

[Jane Somerfield]

Originally posted by Peer Reynders:
I think that it is a matter of target audience. UML stands for "Unified Modeling Langauge" - the "U" doesn't stand for "Universal" (if it did, it would be lying). There have been many claims that UML can be used to communicate with the business owners and domain experts. However UML was developed by people who designed, built and coded object-oriented systems - and ultimately UML was shaped by that perspective. UML is most effective when it is used to sketch out pertinent aspects of a system - as long as the communicating parties are involved with technical aspects of the system. When communicating with business owners and domain experts who lack a OO software development background it is usually easier to ditch UML and use ad hoc "blocks and arrows".

However these ad hoc notations aren't toolable. So Business Process Diagrams were developed as a generic means to represent "Business Processes" to non-technical stakeholders with the ultimate goal of manipulating the actual Business Processes through manipulation of the representations. (The tooling of that notation ultimately creates the risk of the "technical" aspects leaking back into the notation which in turn could alienate its intended audience.)

I'm talking about the Activity Diagram, not Class, Sequence, ...

BPD and BPMN are more complex than the Activity Diagram. We have been using
Activity Diagrams and Use Case Diagrams to the business people very successfully.

[Peer Reynders]

Why BPMN

BPMN follows the tradition of flowcharting notations for readability

A Notation Evaluation of BPMN and UML Activity Diagrams (PDF)

Results from the Workflow patterns framework analysis in chapter six showed that
BPMN has a better representation power in control flow and data -patterns. While both
notations give equally weak results in resource patterns, the only real and meaningful
difference seems to be the lack of external interactions support in UML AD. In this light
the representation power of BPMN can be seen better than UML AD.

Results from the BWW-model analysis in chapter seven were not very considerable. In
many respects the BWW-model analyses against these two notations have very similar
results. Depending on the viewpoint, UML AD could be seen better in representation
power, but only little.

When recapturing this research, the differences between the representation power of
BPMN and UML AD are very narrow. On the whole, BPMN could be seen to have only
a little more representation power than UML AD, because of the better Workflow pattern
analysis results.

Thus, we could conclude, that if there should be a need to choose which notation to use,
the decision can not be done based on the representation power. It is better to base the
choice between the notations on other matters like existing experience on some tool and
notation or equal.

Originally posted by Jane Somerfield:
We have been using Activity Diagrams and Use Case Diagrams to the business people very successfully.

Why are you then worried about it? Use whatever works to communicate effectively - there is no "one right" notation. BPMN and BPD then only become an issue once you have a tool that forces you to use it - that tool probably provides its own context to justify the BPMN vs UML AD choice.
[ March 25, 2008: Message edited by: Peer Reynders ]

[Scott Ambler]

The goal should be to use whatever models, if any, get the job done for you in the situation that you find yourself in. Activity diagrams appear to be working well right now for you so use them. Perhaps on the next project that you're on you'll be working with a bunch of BPMN, which is part of the UML now by the way, people. So BPMN will be the better option.

- Scott
Agility At Scale