Page 157 of the UML Ref. Manual says:
"An association class has the properties of both associations and classes -
it connects two or more classes and it also has attributes and operations."
So it seems to me that the answer is yes, an association class can be linked
to more than two classes as long as the constraint that an instance of the
association is only linked with one unique set of instances of the
associated classes.
There is an example on page 158 showing an association class with a
self-association as the third link. Unfortunately, this is in conflict with
the statement on page 157 that, "An association class may not have itself as
one of its participating classes." But it does illustrate that the
association may have more than 2 participants.
J.D.
My ideas, my words. You can't blame anyone that might employ me for them.
-----Original Message-----
From: george brown [mailto:[EMAIL PROTECTED]]
Sent: Thursday, December 21, 2000 2:19 PM
To: [EMAIL PROTECTED]; [EMAIL PROTECTED];
[EMAIL PROTECTED]
Subject: RE: (ROSE) would anyone give me an detailed explaination of
assoc iation
Hi,
In page 147 of the Guide, we read:
"Sometimes you'll want to have the same properties for several different
association classes. However, you can't attach as association class to more
than one association, since an association class is the association
itself..."
What about linking an "association class" to a "class", other than the ones
it's already associated with? Using the Person-Company example, can we also
associate a Employment (association class, between Person and Company) to
another class such as Salary or EmploymentClerk?
Thanks,
George
>From: "Van Epps, Cindy" <[EMAIL PROTECTED]>
>Reply-To: "Van Epps, Cindy" <[EMAIL PROTECTED]>
>To: "'daniel wang'" <[EMAIL PROTECTED]>, [EMAIL PROTECTED]
>Subject: RE: (ROSE) would anyone give me an detailed explaination of assoc
>iation
>Date: Thu, 21 Dec 2000 09:27:21 -0500
>
>Hi Daniel,
>Refer to the UML Users Guide by Booch, Rumbaugh, and Jacobson, page 147.
>Association class is considered an ad vanced concept in UML. It allows you
>to specify properties of an association. Consider the example of an
>astronaut who flies on space shuttle flights. It is a many-to-many
>relationship. If I need to keep a health record for a particular astronaut
>for a particular flight, I will represent that as an association class.
>This allows my model to clarify the fact that the health record is
>associated with a particular instance of the relationship between astronaut
>and flight. I will use this in analysis, but will have to refactor it for
>design, since (to my knowledge) there are no languages which support
>implementation of this concept directly. The notation allows me to
>represent an abstraction of the concept in analysis rather than lose the
>concept because of the implementation of it.
>Hope this helps,
>cve
>Cindy VanEpps
>Software Engineering Specialist
>Rational Software
>[EMAIL PROTECTED]
>281.648.7996
>http://www.rational.com <http://www.rational.com/>
>
>��Complexity is just a disarrangement of simplicities.��
>
>-----Original Message-----
>From: daniel wang [mailto:[EMAIL PROTECTED]]
>Sent: Thursday, December 21, 2000 9:40 PM
>To: [EMAIL PROTECTED]
>Subject: (ROSE) would anyone give me an detailed explaination of
>association
>
>
>hi :
> i don't really understand the association class in uml. when i should
>make use of them?
>best regards
>
>daniel
>
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