By the way – with reference to data modelling I’m referring to logical or conceptual data models – not physical ones.
The question came up during a discussion at work; naturally I leapt to Wikipedia to get some basic definitions in place – hoping that they might clarify the difference – but they didn’t…
A conceptual schema or conceptual data model is a map of concepts and their
relationships.
Logical Data Modles seem very similar (from this definition):
A logical data model (LDM) in systems
engineering is a representation of an
organization’s data, organized in
terms entities and relationships and
is independent of any particular data
management technology.
Where-as…
A domain model, or Domain Object Model
(DOM) in problem solving and software
engineering can be thought of as a
conceptual model of a system which
describes the various entities
involved in that system and their
relationships.
The differences between domain model vs conceptual data model seems particularly murky.
One of the things which adds to this confusion is that (from what I’ve seen) a domain model is usually modelled using a UML class diagram – the class entity in a UML class diagram supports methods – our colleague maintains that a domain model must not contain “operations”. I can understand domain modellers using a sub-set of a UML class diagram – but isn’t it dangerous to assume people will refrain from including “operations” if the tooling they are using supports it?
Good question, the problem is that it depends on the definion of the terms, I think they differ slightly based on the sources.
I would agree with previous answer – domain models are for describing the problem domain, at least the part you need to develop a solution. You describe all the various entities, their relations and their behaviour. I think that this is also the view from the Domain Driven design perspective.
Data models on the other hand are used for describing the data in your system and relations or associations between them. This is useful for describing what needs to be stored in the system and might also give hints how. I think data models would apply for your “no operations” rule, because they are not important in this respect.