Part 25, UML and BAG or LIST

[David Price]

Folks,

I've read the UML sections on Association and Attribute several times now
and it's become clear to me that UML has no concept capable of supporting
the EXPRESS concept of BAG or LIST with duplicates.  In every case, the UML
spec uses the word "set".

Here's the relevent UML 1.3 text:

UML Association

"The Association represents a set of connections among instances of the Classifiers. An instance of an Association is a
Link, which is a tuple of Instances drawn from the corresponding Classifiers."

UML Attribute (multiplicity)

"The possible number of data values for the attribute that may be held by an instance. The cardinality of the set of values is an
implicit part of the attribute. In the common case in which the multiplicity is 1..1, then the attribute is a scalar (i.e., it holds
exactly one value)."

 I'm at a loss as to what to do.  It seems to me that whatever we do is
going to violate UML. Perhaps we should chose the option that makes that
violation visible? That could mean we'd need to make sure something in the
UML gets named Bag-xxx. Anyone have any bright ideas?

Thanks,
David

IBM Corporation
5300 International Blvd.
N. Charleston, SC 29418, USA
dmprice at us.ibm.com
Phone : +1 (843) 760-4341   Fax : +1 (843) 760-3349
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