Gerald Loeffler wrote:
> Guillaume Rousse wrote:
> >
> > In a well separated layer design, applicative layer should be
> independant of
> > persistance layer. So the use of a OODBMS or A RDBMS should not influate
> > modeling in the application layer.
>
> That's a strong statement! An ODBMS enables you to simply make some of
> your domain objects persistent, and hence puts you in a position to use
> a part of your domain object model as your "database schema" (persistent
> object model). What you are saying is that this approach should not be
> used because it does not result in a "well separated layer design".
>
> Is this an agreed upon view?
>
[Randy Stafford] I think you and Guillaume are in violent agreement
:-) In a well separated layer design the domain layer of an application
should be persistable on both RDBMSes and OODBMSes (or any other persistent
storage mechanism accessible behind a persistence layer).
The open-source FoodSmart J2EE example application on our
"Developer's Guide" CD does exactly this: it can switch between relational
persistence and object persistence according to a property read at startup
time. The domain layer code is insensitive to which persistence mechanism
is in use; that information is hidden by the persistence layer. See
http://www.gemstone.com/javasuccess.
Best Regards,
Randy Stafford
Senior Architect
GemStone Professional Services
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