Do you know if that is a requirement (or even a goal) of the spec, no
changes to an existing normalized schema to use CMP? I agree it does not
look possible to map from your schema to one which will support the spec
without some work on the database.
Cheers
-----Original Message-----
From: Dan OConnor [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, November 01, 2000 2:29 PM
To: jBoss Developer
Subject: Re: [jBoss-Dev] EJB 2.0 spec question
Hi Daniel,
Your two cents are always welcome. Your solution does allow for a
disconnected object as per the specification. However, a deployer
should be able to map an entity using the EJB 2.0 CMP model
without changing an existing normalized schema... especially if it
would mean changing existing data. It would be inappropriate to
require an organization to change existing line-item numbers (that
might be used for various business purposes) just to take
advantage of EJB technology.
I believe the schema I described is quite common in practice.
-Dan
On 1 Nov 00, at 12:04, Daniel Schulze wrote:
> I give my two cents without beeing asked...
>
> Why not like this (in my eyes somehow "cleaner", relationships can be
> added, removed, changed whithout affecting the data, data can be changed
> without affecting relationships in case a bean becomes replaced by a new
> version).
> Every relationship has its own mapping table:
>
> TABLE: order
> order_number (not null and the pk)
> customer
>
> TABLE: line_items
> line_item_number (not null and pk, implizit created by the persistence
> manager and for user and developer transparent)
> product
> quantity
>
> RELATIONSHIP TABLE: order-line_items
> order_number
> line_item_number
>
> This would be easier to handle especially when the objects have many
> relationships.
>
> BTW I dont think the mentioned paragraph from the spec makes sense,
> because it violates the idea of dependend objects (only exist as an live
> reference of a bean).
>
> \Daniel
>
