Guillaume Rousse wrote:
> Entity EJB are kind of white or black solution. CMP is perfect for one
> object=one record model, and maybe even for 1/n or n/m relationships with
> non-standards extension (i didn't tried any). But for really complex
> model, as
> trees, graphs, and so on, you have to switch to BMP, and in this case the
> gain
> over basic Corba solution is getting thiner IMHO.
>
[Randy Stafford] Thinner by lack of one capability, true (the
ability to support really complex models with CMP). But there are still
other differentiators from CORBA, e.g. declarative transaction management
and security, the deployment model, etc.
> What the difference between domain object and business object ? I found
> nothing
> on this topic on cetus links. And is there any online ressources with
> practical
> examples of such a design ?
>
[Randy Stafford] No difference. They are synonyms. The best
treatment of "domain objects" I've seen in literature is in Chapter 11 of
Tim Howard's book The Smalltalk Developer's Guide to VisualWorks. There is
also a book Building Business Objects by Peter Eeles and Oliver Sims. Here
is a contrast of their definitions of terms:
Howard: "a domain object is a logical container of purely domain
information, usually represents a logical entity in the problem domain space
... In general, domain objects should know how to recognize which [of their]
references indicate aggregation and which ones indicate association, copy
themselves, maintain business logic, compare themselves to other domain
objects of the same type, facilitate other objects that choose to print or
display them, and conduct tests on their domain information [to which I
would add validate themselves]".
Eeles & Sims quote the OMG definition: " a business object is
defined as a representation of a thing active in the business domain,
including at least its business name and definition, attributes, behavior,
relationships, rules, policies, and constraints."
Mix the two definitions together and you might have something useful
(I'm not convinced all "business objects" must have names, "definitions",
"rules", "policies", and "constraints").
Best,
Randy
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