We use entity beans to model our Domain Object Model. But the clients never
use those entity beans. Instead the clients use Session beans, which
internally use those entity beans. The session beans interfaces are modeled
to provide some sort of low-level-use-cases to the client. All information
the client needs is provided thru session beans. This information is either
wrapped in serializeable objects or in XML, so the client can work locally
on the data and send it back (thru a session bean) to the server
Mit freundlichen Gr��en
With kind regards
> Ulf Gohde
>
System Architect
> CE Computer Equipment AG Fon: +49 (0)521 9318-167
> Herforder Str. 155a Fax: +49 (0)521 9318-444
> 33609 Bielefeld mailto:[EMAIL PROTECTED]
> Germany http://www.ce-ag.com
>
>
-----Original Message-----
From: john smith [mailto:[EMAIL PROTECTED]]
Sent: Friday, March 10, 2000 9:37 PM
To: [EMAIL PROTECTED]
Subject: Design question: entity beans, wrapping domain objects and
such...
We want to take advantage of entity beans and CMP, but also want to preserve
our Domain Object Model to the greatest degree possible. It is sometimes
suggested that an entity bean simply wraps the java object. The entity bean
would then have two attributes of interest to us, the id, and a reference to
the java object it represents.
Thus we never really act on the entity bean, instead we get the domain
object from it, act upon it and give it back to the entity bean to persist.
We may also do "large" queries using sql in session beans, construct our
domain objects from the results, and when done, pass them back to an entity
bean for transactional updates.
I would like to expose only the domain objects to the clients (session
beans) probably using a facade of some sort with which our "findBy" requests
would be delegated to the actual entity bean and the facade would return
back to the client, domain objects.
Questions:
First - I'd like to know if anyone is using domain objects wrapped by entity
beans, and if so, can you provide some insight into how you actually use the
domain object from a client. Thoughts?
Heres the first thing I come up with:
Lets say we want to use a simple mutator on a domain object, for example,
change a patients telephone number.
1 - the client makes a request for patient with last name of smith.
2 - If we were directly accessing entity beans from the client (session
bean) we would have 3 remote references, update the one of interest and the
container would insure it was persisted...
In our case we get back three domain objects. We update the one of interest,
and then what??? Sure, we submit it back for persistence. The facade will
use the id to look up the entitybean, update it and persist it. But this
seems like a lot of work!
Any other ideas?
THANKS!!!
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