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Semantics of Association and Aggregation/Composition [message #628279] Mon, 01 March 2010 23:09 Go to next message
amir  is currently offline amir Friend
Messages: 4
Registered: March 2010
Junior Member
Hi All

My question is very trivial and at the same time very technical.

Suppose, we have a system, where there are 5 Universities. Each university is composed (Composition) of 10 departments. And each department has 20 faculty members (Composition) and 10 courses (Composition). Also, we have an association of "teaching" between faculty members and courses. Now the question is, 1) Considering the type of aggregation is composition and faculty members and courses strictly belong to one and only one department, Does this mean that faculties must teach courses strictly offered by the same department or they could take courses from other departments without conceptually belonging to/ working for them? Wouldn't make sense if we had shared aggregations instead of compositions in case of the relationship between department and faculty, making it possible for one faculty to work in other departments and then taking courses offered by other departments? 2) taking the original design using compositions, Is it possible to have one faculty to take courses from other universities, without conceptually working for it? Note that this hierarchical composition could be extended. 3) how is it going to be implemented code generation-wise, considering one particular department owns instances of faculty and courses, and at the same time handling the association between their instances?

This is just an example, so don't restrict yourself to this example.

With Regards
Re: Semantics of Association and Aggregation/Composition [message #628280 is a reply to message #628279] Mon, 01 March 2010 23:22 Go to previous message
Ed Merks is currently offline Ed MerksFriend
Messages: 26283
Registered: July 2009
Senior Member
Amir,

Comments below.

amir wrote:
> Hi All
>
> My question is very trivial and at the same time very technical.
>
> Suppose, we have a system, where there are 5 Universities. Each
> university is composed (Composition) of 10 departments. And each
> department has 20 faculty members (Composition) and 10 courses
> (Composition). Also, we have an association of "teaching" between
> faculty members and courses. Now the question is, 1) Considering the
> type of aggregation is composition and faculty members and courses
> strictly belong to one and only one department, Does this mean that
> faculties must teach courses strictly offered by the same department
> or they could take
You mean teach?
> courses from other departments without conceptually belonging to/
> working for them?
Given you said teaching is an (arbitrary) association, any faculty
member could teach any course regardless of the department that contains
the faculty member or the course.
> Wouldn't make sense if we had shared aggregations instead of
> compositions in case of the relationship between department and
> faculty, making it possible for one faculty to work in other
> departments and then taking courses offered by other departments?
You again mention "taking courses," but you've not defined that concept.
Only the concept of teaching. The concept of "work in" has also not
been defined.
> 2) taking the original design using compositions, Is it possible to
> have one faculty to take courses from other universities, without
> conceptually working for it?
Taking and working for are not defined yet.
> Note that this hierarchical composition could be extended. 3) how is
> it going to be implemented code generation-wise, considering one
> particular department owns instances of faculty and courses, and at
> the same time handling the association between their instances?
You're question is way too vague.
>
> This is just an example, so don't restrict yourself to this example.
Where are you going with this line of reasoning and questioning?
>
> With Regards
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