The design principles of EJB are much the same as those of CORBA
components.
Consequences
1. More complex interfaces.
2. Tighter coupling
3. Reduced cohesion
Rules Of Thumb
1. Objects must be a Component (Entity) if it is referenced/used
directly by more than one
other object and must have a unique identity.
2. If an object if owned by another object then it should be a Dependent
of a Component
rather than an Entity.
3. Objects that are lazy-loaded might be components
4. Objects that are not lazy-loaded are often not components
5. Try to avoid polymorphic components
6. Entity Beans should concern themselves with data, relationships and
validity
7. Session Beans should implement Business Logic and Transactions
8. Archive and carefully study all postings by Rikard Oberg
> -----Original Message-----
> From: Michael Schuerig [SMTP:[EMAIL PROTECTED]]
> Sent: Tuesday, July 06, 1999 8:59 AM
> To: [EMAIL PROTECTED]
> Subject: Entity bean granularity
>
> My understanding is that entity beans are meant to be components that
> may realize parts of design models encompassing more than a single
> class. Now, this sounds fine in the abstract, but what are the
> concrete
> consequences? Let me put it like this:
>
> - Taking the usual multi-tier stuff for granted, what are the specific
> influences of EJB on design?
> - What strategies are there to allocate domain objects to entity
> beans?
> - What strategies are there to allocate functionality to session
> beans?
> (Is it reasonable to represent Jacobson's "control classes" through
> session beans?)
>
> TIA,
> Michael
>
> ======================================================================
> =====
> To unsubscribe, send email to [EMAIL PROTECTED] and include in the
> body
> of the message "signoff EJB-INTEREST". For general help, send email
> to
> [EMAIL PROTECTED] and include in the body of the message "help".
>
===========================================================================
To unsubscribe, send email to [EMAIL PROTECTED] and include in the body
of the message "signoff EJB-INTEREST". For general help, send email to
[EMAIL PROTECTED] and include in the body of the message "help".
