[news.eclipse.tools.gef] Re: Non-binary connections - how do you model t

[Jens v. P. <usenet@xxxxxxxxx>]

On 2004-12-02 05:53:48 +0100, Barry Lay <blay@xxxxxxxxxxxxxxxxxxx> said:

> I have a requirement for a non-binary association between objects, and 
> am curious about how one might model it graphically.

I think there are two possibilities:

1) Model the association as (invisible) node
The association is modeled just like the assiciation in UML 2. The 
association is represented as a node, and every linked "real" node is 
connected with a binary connection. Maybe it's possible to hide the 
association node itsself, e.g. by creating a figure with dimension 
(0,0) or (1,1). If you have to move the association node -- the user is 
moving the center point of the n-ary association -- the bounds of the 
node might be greater and you have to provide proper anchor points. The 
advantage of this apporach is that you have to managy binay connections 
only.

2) Model the association as Connection and Node
You can implement both interfaces, the Connection and the Node 
interface. That's no problem. I've implemented a class diagram editor 
and I needed this for conecting Comments to a Relationship, e.g. 
connect a Comment to a Generalization with a CommentLink-Connection. 
The result may look like the first approach and you can use bendpoints 
for the same puprpose as the center node in the first approach.

Depending on where and how may labes and other decorations you have to 
provide, maybe the first or the second approach are more suiteable for 
you. Maybe I like the first case more since it's more straight forward.

Jens