Re: Understanding Agrregates

Hi Rikard,
I'm using standard UML definition: "association" is for nondescript connectors, aggregate and composition for special ones.
So if accounts can be shared by several customers I will not use aggregates.
More generally, the objective is to use an unambiguous semantics for connectors requirements independently of design (entity or value object).
The same outcome can be obtained in terms of objects life-cycle:
Composition: same life-cycle.
Aggregate: independent life-cycle but exclusive ownership
Simple association: independent life-cycle and no or non exclusive ownership.
You're right about domains, but the terminology may be confusing because there are two kinds of domains:
*one for objects shared by different applications (continuity of identities and consistency of structures).
*one for objects managed by specific applications (continuity of transactions and consistency of semantics).
See for instance:
http://caminao.wordpress.com/how-to-implement-symbolic-representations/objects-with-attitudes/ http://caminao.wordpress.com/how-to-implement-symbolic-representations/objects-with-attitudes/
Regard.
Rémy.