Author Topic: Visualising Classifier Relationships  (Read 6416 times)

Simon M

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Re: Visualising Classifier Relationships
« Reply #15 on: May 04, 2016, 09:02:49 am »
Ah, well. The thing there is that UML has no concept of a browser-type containment hierarchy. The standard specifies what various entities should look like and how their relationships should be interpreted, but it does not specify how model data should be stored or navigated.
This is a bit off-topic from the original thread, but while it's true that UML doesn't specify what the UI or storage of a model should be, (and it shouldn't) it is clear on ownership. The tree/browser hierarchy in EA corresponds to the ownedElement/parent association that is subclassed by many associations.

Also, UML 2 doesn't actually define a nesting connector as such (or at least not one that specializes from DirectedRelationship). It's an optional notation to describe ownership.
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Paolo F Cantoni

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Re: Visualising Classifier Relationships
« Reply #16 on: May 04, 2016, 09:48:41 am »
Ah, well. The thing there is that UML has no concept of a browser-type containment hierarchy. The standard specifies what various entities should look like and how their relationships should be interpreted, but it does not specify how model data should be stored or navigated.
This is a bit off-topic from the original thread, but while it's true that UML doesn't specify what the UI or storage of a model should be, (and it shouldn't) it is clear on ownership. The tree/browser hierarchy in EA corresponds to the ownedElement/parent association that is subclassed by many associations.

Also, UML 2 doesn't actually define a nesting connector as such (or at least not one that specializes from DirectedRelationship). It's an optional notation to describe ownership.
Good points Simon, to which I'd add the following (hopefully) insights I've garnered along the way.
Firstly, I don't believe UML defines what Ownership MEANS (I stand to be corrected).  However, in this case, it seems to mean the following:  If I have an owned element, I control how you may address (access) it.  If I am X and I have owned element Y, then you can ONLY reach Y via X.Y.   Further, while I own Y, if I am destroyed, then my owned elements are destroyed.  Because of the X.Y relationship, we say Y is "nested" in X.  The semantics of Nesting are similar to Composition, but they aren't the same - hence the different rendering of Nesting versus Composition.

There are many ways of representing relationships.  There are many ways to render relationships.  We've taken the view that all relationships should be renderable as arcs.  However Uffe's point about conditionally rendering some types of relationships (of these kinds) is a good one.  The issue is one of not hiding information that may be useful, if visualised.  As I say:  "When you can see the problem, you can SEE the problem!"

Paolo
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Glassboy

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Re: Visualising Classifier Relationships
« Reply #17 on: May 04, 2016, 01:32:57 pm »
Good points Simon, to which I'd add the following (hopefully) insights I've garnered along the way.
Firstly, I don't believe UML defines what Ownership MEANS (I stand to be corrected).  However, in this case, it seems to mean the following:  If I have an owned element, I control how you may address (access) it.  If I am X and I have owned element Y, then you can ONLY reach Y via X.Y.   Further, while I own Y, if I am destroyed, then my owned elements are destroyed.  Because of the X.Y relationship, we say Y is "nested" in X.  The semantics of Nesting are similar to Composition, but they aren't the same - hence the different rendering of Nesting versus Composition.

Paolo, standing for konsistency and systemic violence :-)