Re: Searching OO Associations with RDBMS Persistence Models

Robert Martin wrote:
> It's not a matter of preference. Application objects are often complex
> assemblies of many different tables and relationships, all of which
> have their own keys. Which of those keys is the identity of the
> application object?
>
> For example, I once worked on a network management system in which
> circuits were terminated by CSUs. There was a CSU table and a circuit
> table. Logical connections between parties could use many different
> circuits. The application objects that embodied these logical
> connections were complex assemblies of circuits and CSUs. They were
> semantic elements that had identity; but they weren't database
> entities, and so the concept of "key" was superfluous.
>

...
>
> Sorry, what I mean is that the database keys are not unique identifiers
> for the logical application entities. For example the key for a
> circuit could not be used to identify a logical connection. A logical
> connection is a semantic entity, composed of elements from the
> database. There is a need for these semantic entities to have
> identities which are not just database keys.

Could you be more specific, please? You have

table Circuits (
...
)

table CSVs (
...
)

What important attributes are there? Sample data too (couple of records to make the matter clear would suffice).

Then, what application object looks like?

(Crossposted c.d.t, as I quit following c.o). Received on Mon Jun 05 2006 - 22:35:18 CEST