[ontoiop-forum] Call for final comments on DOL, UML

[Till Mossakowski]

Dear Conrad,

in response to your comments, Alexander Knapp writes:

Thanks for the comments.

“Not sure I'm reading this correctly, but it seems to say the properties 
involved in a composition association are properties of m, whereas they 
are usually properties of the classes at the ends of the association.”: 
It is not intended to express ownership here.

“Properties can be composed without being member ends of an 
association.  The UML 2.5 spec describes aggregation in the Property 
subclause (9.5.3), without constraining the properties to be member ends 
of associations.  The phrase quoted here describes a composite property 
with ("grouping its") values.  Feel free to ask Ed and others, this is 
well known to be the interpretation of the spec, and is implemented in 
tools.”: Yes, indeed, a property itself could be composite without being 
a member end of an association.  I only now get the semantics of such a 
declaration, say, c.p : \tau’[c’] with p composite (if I understand 
correctly): it would be that if o is an instance of c, and o.p are the 
values for property p, these values are parts of o (and, hence, deleted 
if o is deleted – which we do not discuss); each such value can only be 
contained (as a part) in a single object.  Currently, we only discuss 
the case where a composite property is a member end of an association, 
but with this clarification we could also handle the “non-member end” 
case by adding to the definition of “attributes” that p may also be 
decorated by a filled lozenge and adding the ownership semantics.  In 
any case, the text starting with “In UML, each Property may have 
AggregationKind composite” should either clarify that we only discuss 
the “member end” case or could be skipped altogether. (The quote with 
“grouping its” is now on page 110 of the UML 2.5 specification, the 
constraint for member ends of binary association on page 218.)



All the best,
Till

Am 08.10.2015 um 17:27 schrieb Bock, Conrad:
> Till et al,
>
> Took a quick look and the interpretation of composition is
> still wrong, see attached.  Apologies for not having looked
> at this earlier. Will review more carefully for the Oct 15
> deadline.
>
> Conrad
>
>
>
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