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Re: [mdt-papyrus.dev] general UML 2.5 questions

hi ed,

On Tue, Oct 14, 2014 at 04:29:01PM +0100, Ed Willink wrote:
> If you want to mangle elements together you are free to create whatever
> variety of spaghetti satisfies you.

obviously, and of course that spaghetti mess and non-standard behaviour
is what I am trying to avoid :)

> XMI and tooling have policies for resolving href's so your comments about
> knowing how to find things leave me totally confused. I see no significant
> difference for users between UML 2.4 and 2.5.

there may not be a significant difference between 2.4 and 2.5, except
for the fact that I have not seen XMI output from any 2.4 tool that
actually uses DI, all I have seen is self-brewed bits for the diagrams.
With 2.5 DI becomes more relevant, and that's where this comes up.

also note that this has nothing to do with hrefs at all, it is the
"implicit" relationships that get me confused. looking at the example
(from the OMG mind you):

> ><xmi:XMI ...>
> >     <uml:Package xmi:type="uml:Package" name="PrimitiveTypes" ...>
> >         <packageMerge xmi:type="uml:PackageMerge" ...>
> >             <mergedPackage xmi:type="uml:Package" href=...>
> >         </packageMerge>
> >         <umldi:Diagram xmi:type="umldi:UMLClassDiagram" ...>

the href in the mergedPackage is of course easy to resolve, but you will
notice that there is also a relationship between the packageMerge and
the uml:Package that is not expressed through references, but merely
through the fact that the packageMerge is a child node of the
uml:Package in the XMI. And the tag name "packageMerge" is relevant
because it says which property of the object representing the package in
the abstract model receives the packageMerge object. agreed?

now where my confusion comes in us the umldi:Diagram element, which has
the same type of relationship with the uml:Package element. This also
nicely lines up with the general user experience of a UML tool, where
diagrams are typically associated with a package. However, I do not see
how that association can possibly be expressed in the abstract model.
Which property of the object representing the package would hold the
reference? even if there was such a property? how would the XMI reader
know which property to use given that it doesn't say in the XMI?

again, please keep in mind that I am coming from a MDA / metamodeling
point of view. If the tool "just" needs to support UML, and loads of
knowledge about the metamodel can be built into the tool, then that is
of course not an issue.

thanks  robert

-- 
Robert Lemmen                               http://www.semistable.com 

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