USE CASE UML Modeling different ways to System access (SMS, IVR, WEB)

I’m working on a USE CASE diagram but I’m having problems modeling the following: A user wants to inquire his balance, but he ca开发者_如何学JAVAn do it by phone, SMS or IVR. How should I represent the different ways? Each one has different flows. Should I model just one use case for each one, or should I represent the different ways as extended use case.

If the three cases share flow to a huge extent (say >70%) I would model them as one use case. Otherwise it would be better to model three different use cases.

The point here is understandability. Cramming three different things into one is confusing, repeating the same three times is confusing as well (although probably less).

There is no right or wrong answer to your question. UML allows the same situation to be modeled differently. It depends mainly on the level of abstraction you choose for your use case diagrams.

You'd have a common use case with 3 extensions. You'd then detail each extension with sequences diagrams.