Hi Manish,
Your question is very interesting because it is a common issue that many
people have when starting modeling in UML.
I have read several books about UML, i have followed a rational course
about analysis and design and have looked for answers into the Rational
Unified Process. Now, I found an answer that satisfies me...
Let us compare both approachs:
1) fine-grained use cases (example : place order, cancel order, validate
order...).
You model the sequences of actions at user' s level and each use case is
driven by only one actor . Scenarii are generally not very complex because
they do not express workflow. You can model them with activity diagrams but
there will be only one swimlane. Sequence diagrams are generally be more
useful because they make appear some objects and help you separate
responsabilities.
Your use cases do not show the order life cycle and you need a higher level
view to have a global view of your process. If you do not model a process
view, you take the risk not to have a coherent system.
2) process-grained use cases (example : purchase order)
You model the process and have a global view of your system. You can show
the different states of an order and you can model the workflow through an
activity diagram. Your use case is "customer" oriented in the sense it
expresses what is done to realize the "purchase order" process.
Now, let us consider the commercial director point of view (let us suppose
this actor is in charge of validating orders). From his point of view, this
actor will probably want to have orders grouped and validate many of them
in one scenario, for instance with check boxes and a final validation. This
scenario is not at the same level than "purchase order"...
Conclusion :
-----------------
As for me, i consider that both views are necessary.
A "process" view is fundamental to get a global view of the future system,
but I consider that it is a customer oriented' view that can be different
from user' view. I put this approach into "business modeling" and I call
these use-cases "business use cases".
The first view, with one use-case for "place order", one for "validate
order"... shows (for me) the real system use cases, because they answer to
objectives at user' level. I can easily add a new use case "validate orders
by group" that will extend "validate order" without any impact on the other
use cases.
I hope I have not missed the question and I could help solving the issue,
Raphaël Faudou
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"Manish Didwania"
<mdidwania@amadeusi To: "ROSE_FORUM"
<[EMAIL PROTECTED]>
ndia.net> cc:
Sent by: Fax to:
owner-rose_forum@ra Subject: (ROSE) Use Case-confusion
tional.com
22/10/2001 10:26
Please respond to
"Manish Didwania"
I just want to know what is the common practice. In terms of putting
Activity Diagram in Use Case.
And at what level one should specify a Use Case. As I was reading a book on
UML it was dividing a Purchase Order Use Case in 4-5 diff use case like
Placing an Order, Cancellation of order and so on. And in rational few
examples that I had checked they define Use Case for purchase Order as one
Use Case and then specify the activity in documentation.
Thanks Manish
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