Relationships between Activity and Business Proces

[Scott Lindner]

For starters... I'm UML ignorant.  I read the UML Distilled cover to cover and dabble with it to convey some engineering artifacts at work.  I'm currently struggling with the appropriateness of one dynamic model over another.  What are the intended differences between an Activity Model and a Business Process Model?  What are the relationships between the two?

Thanks for any help with this.

Cheers,
Scott

[Bruno.Cossi]

Hi Scott,

Business Process Model/Analysis Model is also referred to as "Simplified Activity Model" which is exactly what it is. In real life, the Business Process Model would likely be the first one that would get created (should you choose to use it at all). It would capture the business processes in high level, it would illustrate what triggers the process (events), what the outputs are etc. The level of detail in the business process is typically not very deep.
Only later on would you create the Activity Diagrams, which are more detailed, often reside under Use Cases (hence, you typically build much of the UC prior to the Activity Diagrams), often refer to the Actors, Classes etc.

Bottomline: Business Process models are much less detailed, but you can build them very early in the project. Activity Diagrams contain much more detail, but you won't be able to build most of them until later on.

Hope this helps a little!

Bruno

P.S. Have a look here: http://www.sparxsystems.com.au/business_process_model.htm

[sargasso]

Scott,

Just to add to Bruno's answer.

As he says, you may or may not want/need to include business processes in your models for a particular system.  In fact, you may or may not want/need to include business process models for parts of your system.

Here, we use them as a means to validate any specific use cases that are unclear or otherwise "suspicious".

The beauty of them is that you can model the process at a very high level - while getting down the salient points of interest to the system designers.  What I mean by this is, ...
Previous pocesses and notations (e.g. IEDEF, etc) involved a very detailed analysis of a business process, looking at either the data flows or the activity flows within the process.  All very fine and good if the process is likley to change.  However, if the process is reasonably stable, the only information that is truly needed at the requriements/analysis/use case modelling stage is that info indicated by the first diagram in http://www.sparxsystems.com.au/business_process_model.htm  
From these simple enunciations we can check that a use case is aligned with the business process, and if not explore it further with the stakeholders until we are sure that what we understand is what they understand.

Activity models on the other hand, can be used to explore the inner mechanistic steps (behaviour) of many
elements and features - processes, methods, etc etc.  They a common way of representing the inner workings of some behaviour (there are dozens of threads in these forums on their use in specific instances e.g. analysing use case scenarios etc).

We also find that activity models are "easier" for stakeholders to comprehend than state, sequence and collaboration diagrams.  The latter are used in the technical design of the system and IMO should not be forced on the uninitiated.

IOW - (business) process models are "semi-structural", they are used to describe the gestalt of a process, gleaning the needed information quickly and effectively.  Activity diagrams are used for detailed analysis of the stepwise, atomic level behaviour of both the business and the system.


hth
Bruce