Class associations and multiplicity - UML 2.0 - object oriented (Basic)

Question

I am learning UML and I've focused on a Netflix-like project on which to practice on.

I've put together a class association diagram, but have been told that the multiplicities are incorrect. The multiplicities in red represent what I think they should be changed to.

Could someone please offer some clarity of where I have gone wrong?

Please, ask any questions that would help gain a fuller understanding of the diagram in reference to the project.

Thanks in advance.

qwerty_so · Answer 1 · 2018-03-30T11:27:02.950

0

Movie Catalog - User: The 0..* multiplicity is correct. There can be an arbitrary number of users and not only a single one. That would only work if that Netflix was made for a very single person. And that would be pointless, I guess.

Movie - Membership - Member: This represents an association class for the user to track payments (and access, etc.). So it must be the 1, not 0..*. The stream is sent for that single Membership where it is accounted. An association class has a n-1-1-m relation.

In your model it looks like this:

And from my POV it is:

since the Membership is just used to control access to the movies. It is arguable whether there is only a 1-1 relation and not a (preferable) m-1 relation between Member and Membership.

edited Mar 30 '18 at 11:27

answered Mar 30 '18 at 09:30

qwerty_so

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I would think a movie could be streamed by more then one membership. So that would result in `0..*` at the Membership end, not `1`. – Geert Bellekens Mar 30 '18 at 09:47
@GeertBellekens No. The stream is for that single membership where it is accounted. It's an Association Class thus a N-1-1-M relation. – qwerty_so Mar 30 '18 at 10:06
I don't see any association classes in this diagram. – Geert Bellekens Mar 30 '18 at 10:44
No seriously. Which association has an association class? I don't see any dotted lines from an association to a class. – Geert Bellekens Mar 30 '18 at 11:33
@GeertBellekens I did not say, that it's denoted that way in the OP's diagram. – qwerty_so Mar 30 '18 at 11:55

Class associations and multiplicity - UML 2.0 - object oriented (Basic)

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