Terminology - parts of a composite relationship

Question

Assume I have a composite relationship, say a Customer having a collection of Orders (and assuming an Order cannot exist without an "owning" Customer.) So, I'm not talking about aggregation.

What terms are used to describe the roles in this relationship? I might say the Customer is the "owner" of an Order and maybe the Order is "owned", but surely there are better terms, terms that can be stated without referring to the other role.

I'm trying to determine these terms so I can propertly name attributes in a meta model. I can "make something up", but would like to use names that will be easily understood.

Thanks in advance for suggestions and/or pointers to definitive sources.

Bill

Answer 1

This is also called the "has a" relationship. The Customer object "has a" collection of Order objects. Where as in inheritance, you'd say the Customer "is a" Person. You could also say the collection of Orders is a field or member or whatever you're language calls member variables. You'd just call the Customer an object (or a composite type). Most classes are composite types anyway, unless there's no state (i.e. just methods/behavior).

Answer 2

You want the "has a" relationship; our thing "has a"nother thing attached, as opposed to inheritance of "is a" relationship. You can build fairly robust models around just those two relationships. But.

To postulate further, in Topic Maps (since we're talking about meta models) we have a few in-built relationships which also has global identifiers (which you could use for global knowledge / data exchange), which are the supertype-subtype (denotes hiearchies) and the type-instance (denotes typification, a strongly typed "is a") relationships. These are fairly global (meaning, also outside the Topic Maps world). Have a look at the end of the Topic Maps Data Model for more on this.