Sparx Systems Forum
Enterprise Architect => Uml Process => Topic started by: Marjohishe on May 16, 2025, 06:51:47 pm
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Hi all,
Which UML diagrams do you find most effective during the requirements phase? I'm currently using use case and activity diagrams—wondering if there's anything else you'd recommend.
Thanks!
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Use case diagrams for sure - but there's an art to structuring them to maximize their value.
Under each use case, one or more sequence diagram. The sequence diagram is by far the best way to capture who is using what information, what attribute, how they use it and why. This is invaluable for data modeling but also system architecture, and also test definition.
Activity diagrams don't add much value beyond maybe user interface design as they just show procedural steps without capturing what information is used, where it comes from, where it goes to. Personally I avoid them.
My 2c good luck!
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Hi
I wrote an eBook about all this (Rquirement Diagram, Use Case Diagram and Activity Diagram; you can find it at https://leanpub.com/uml-erpworkshop
Happy reading
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The sequence diagram is by far the best way to capture who is using what information, what attribute, how they use it and why.
...
Activity diagrams don't add much value beyond maybe user interface design as they just show procedural steps without capturing what information is used, where it comes from, where it goes to. Personally I avoid them.
Interesting take. Have you played around with using Activity Parameters, ObjectFlows supported by a rigorous data model etc?
To answer the original question, Use Case diagrams are a good way to organise requirements. It depends entirely on what format your requirements take though, of course. If your requirements are modelled as UML Requirement Elements in EA then UC diagram works, or a Class diagram if you want to show different requirement types and how they relate to / inherit from each other (and many other ways to manage the requirments structure).
If your requirements are modelled as Activities then naturally a set of Activity Diagrams is what you need (similar for requirements modelled as Sequences, Class structures etc...).
For me, in summary, there are few 'rights and wrongs' because it depends on what you're trying to achieve, and that will be different depending on the design, the system, the requirements management philosophy, the customer....
I wrote an eBook about all this (Rquirement Diagram, Use Case Diagram and Activity Diagram; you can find it at https://leanpub.com/uml-erpworkshop
I'd be interested to read this! :)