Re: A Question about Domain Object

"narke" <steven@xxxxxxxxxxxx> wrote in message
news:1113399075.777541.81280@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> A definition (http://c2.com/cgi/wiki?DomainObject) about Domain Object
> says domain objects should know how to recognize which [of their]
> references indicate aggregation and which ones indicate association.
>
> This definition leads me to think following questions:
>
> 1, How to understand the statement?
>
> 2, What is the real difference between aggregation and association?
> Further, if a class A has a method which take another class B as its
> parameter, in the case, does A gets an association with B? If this
> method happens to be a contructor of A, does A gets an aggregation with
> B in this case?

Quite sursprisingly, perhaps, is the fact that the industry consensus is to
treat "domain objects" as pure information objects with little or no
business logical besides constraints on navigability, cardinality and value
domains. Business objects / services act on domain objects. In a layered
design, domain objects is typically the only allowed kind of object to float
between layers.

To some OO purists, this model is not a good one, but it is good engineering
to separate problems like this for the sake of maintainability, distribution
and persistence.

The wiki definition does not reflect the industry's interpretation of the
term.


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