Re: Business Methods in an Entity Beans

[Chip Wilson]

gee Martin wrote:
Hey Folks,
I have a couple of questions (I'm curious to your opinion(s))
My opinions, then.
1. Is it advisable (under any circumstances) that
Entity beans should have
business methods or behavior?
Methods yes, behavior probably not, if you mean the actual implementation
of the business behavior.
E.g. (fictitious example) A Customer entity
bean which has a Email Contact dependent object. Should the Customer
bean
have the behavior to use the Contact object the contact the customer?
Absolutely, though the behavior should probably be implemented in a dependant
object (like Customer, as opposed to CustomerEntity). 
Entity beans are facades to graphs of persistent domain objects.
2. Dependent objects. Is it OK for these objects
have behavior or business
methods? E.g.
                        
Customer
                              
|
                             
/  \
                          
/        \
                
Contact      Address
Where Contact and Address are dependent objects (they live and die with
the
customer entity). (IMHO These are pseudo entity beans since they represent
database tables)
IMNSHO entity beans do not represent database tables, they are coarse-grained
components.  They serve as facades to graphs of persistent, fine-grained,
dependant domain objects.
Is it OK for the Customer entity to have a business
method
which exercises behavior in the Contact Object (contact a Customer)?
Yes, though the implementation of the business behavior should be delegated
to a fine-grained domain object.  I would have a class called CustomerEntity,
which implements the bean logic and serves as a facade to the domain class
Customer, as well as all of its dependant objects, such as Contact
and Address.
TIA,
Martin
There are numerous discussions of these topics in the archives.  I
also had an article published in the 8/99 issue of Component Strategies
where I discussed my point of view on these questions.
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