When a Composition ISN'T

[Paolo F Cantoni]

Those of you who've been long-time members of the forum will recall my railing (over 5 years ago now) about how fundamentally broken the EAComposition and EAAggregation connectors were...
I've therefore religiously (certainly zealously) avoided them "like the plague" in the interim.  However, as I've previously indicated, I'm FORCED to use them - because there's no other way to achieve certain outcomes with MDG Technologies.

When creating an MDG Technology, one can create a metaclass of "Composition" by using the dialog on drag.  Similarly, you can create a stereotype in Settings|UML...|Stereotypes with a base class of "Composition".

There's only one small problem...  You can't create connector of type "Composition".  Indeed, take any non Composition connector and try <Context Menu>|Advanced>|Change Type... - you'll see that "Composition is NOT one of the available selections.

The reason for this is that an EAComposition (as opposed to a Association with composite aggregation) is actually a connector of type "Aggregation", subtype "Strong".  Similarly, an EAAggregation (as opposed to a Association with shared aggregation) is a connector of type "Aggregation", subtype "Weak".  It would be a good idea to remove these spurious entries rather than leave them around to confuse poor sods like me...

So if you're wondering why your stereotype shapescripts for composition base types don't seem to work very well... This is why.

Reported,
Paolo

[Paolo F Cantoni]

See: Aggregation and Association proposal for a proposal to provide consistent processing and rendering of EA Aggregations, Compositions and Associations.

HTH,
Paolo