Dot

[zyx]

Hello,

    What is the function of the Dot in association ends? Someone can give me a practical example?

[Geert Bellekens]

What do you mean by "Dot"?

Geert

[Nizam Mohamed]

The "Dot" signifies that the association end is owned by the class.

Note: In EA 'navigablity" also plays a vital role in determining association ends ownership

[Paolo F Cantoni]

The "Dot" signifies that the association end is owned by the class.

Note: In EA 'navigability" also plays a vital role in determining association ends ownership

Hi Nizam,

Do I correctly interpret that UML doesn't require navigability and ownership to be interrelated?

Also, you did mean UML Navigability and not Directionality (which end is the Origin and which the Destination) since EA also conflates the two ideas somewhat?

Paolo

[Geert Bellekens]

I think since UML 2.0 they've untied the navigability and ownership concepts.
Before the common convention was that if an associationEnd is navigable it was owned by the other side. (since that entity could navigate the association).

Usually this convention still holds, I can't really think of any examples that prove otherwise.

Geert

[Nizam Mohamed]

Hi Paolo,
"isNavigable" is now a derived property in UML (isNavigable = not classifier->isEmpty() or association.owningAssociation.navigableOwnedEnd->includes(self))

where as it used to be a property of the associationend metaclass(now demoted)
"Navigability notation was often used in the past according to an informal convention, whereby non-navigable ends were assumed to be owned by the association whereas navigable ends were assumed to be owned by the classifier at the opposite end. This convention is now deprecated."   -- UML 2.1 superstructure - Page 46

EA still relies on navigability to influence the direction and ownership (which still holds true to some extent),

The dot notation has been introduced in UML2.x to essentially represent graphically that the association ends are owned by the Classifier ( and not the association )

Ownership of association ends by an associated Classifier may be indicated graphically by a small filled circle, which for brevity we will term a dot.  -- UML 2.1 superstructure - Page 46

[Frank Horn]

Before the common convention was that if an associationEnd is navigable it was owned by the other side. (since that entity could navigate the association).

Usually this convention still holds, I can't really think of any examples that prove otherwise.

What if both ends are navigable?

[Nizam Mohamed]

each associationend is a property and if both ends are navigable they are owned by the respective classes(opposite ends)

[zyx]

Thank you for the help, but someone can give me a practical example? When we have to use the dot and when we have to use navegability?

[KP]

When we have to use the dot

You don't have to use the dot. The UML specification states: "This standard does not mandate the use of explicit end-ownership notation, but defines a notation which shall apply in models where such use is elected."

and when we have to use navegability?

And the standard states: "Navigability notation was often used in the past according to an informal convention, whereby non-navigable ends were assumed to be owned by the association whereas navigable ends were assumed to be owned by the classifier at the opposite end. This convention is now deprecated."

It seems to me you have two choices: 1. Don't bother with dot notation, or 2. (assuming you're modelling for code generation) Place a dot everywhere where you expect an attribute/property to be generated in the class at the opposite end.

[philchudley]

Ok you got me, how do you create the AssociationEnd element and make the "dot" visible on a class diagram?

Searched the on-line help and the EA v 8.0 user guide, seen an example, and many references, but no help on how do it.

Cheers

[Geert Bellekens]

Phil,

Try the "owned" checkbox in the Source/Target role tab.

Geert

[philchudley]

Thanks Geert, obvious really, well its is Monday morning!