beyond this, the intelligence of the CMP is very important. depending on
scalability requirements, a critical feature is tuned updates (whereby the
actual dml sent to the database is the minimal required dml - eg only dirty
data is sent). you'll discover dml that apparently changes no data (old and
new values are identical) can cause enormous transaction log, locking, and
paging activity in the database (not to mention the network). a related
topic; database drivers have a tremendous impact on everything as well.
> -----Original Message-----
> From: Anne Thomas [SMTP:[EMAIL PROTECTED]]
> Sent: Tuesday, November 09, 1999 3:48 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Container supported persistence... mapping?
>
> Actually, Oracle doesn't support container managed persistence. Oracle
> recommends using only stateless session beans, and the O4BC tool generates
> all of the data manipulation code for you.
>
> The mechanisms of container managed persistence are not defined by the
> specification. Therefore each vendor implements the service in its own
> way.
> The capabilities of the various implementations can be dramatically
> different.
>
> <I apologize up front if I offend any vendors here. My comments are purely
> to demonstrate the differences between the implementations.>
>
> For example, WebLogic provides relatively primitive CMP services. The
> native
> service allows you to map a single object to a single row in a table. You
> define the mappings while deploying the bean using WebLogic's deployment
> tools. WebLogic also allows you to plug in alternate CMP mechanisms such
> as
> an O/R Mapping tool (TOPlink) or an object database (Versant or ODI). The
> mapping mechanism depends on the CMP mechanism used.
>
> At the other extreme, Persistence PowerTier provides exceptionally
> comprehensive CMP services. You use the Persistence development
> environment
> to generate objects from your database or the generate a database from
> your
> objects. Persistence supports very complex mappings of object data to
> relational tables. The downside to the Persistence approach is that the
> entity beans that you develop with PowerTier are not portable to other EJB
> implementations.
>
> Anne
>
>
>
> -----Original Message-----
> From: Robert Nicholson [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, November 09, 1999 12:30 AM
> Subject: Container supported persistence... mapping?
>
>
> With the EJB projects that currently support container supported
> persistance. I assume sybase's and oracle's do. How is the mapping
> b/w the persistence properties of the bean and the schema of the database
> specified?
>
> Is schema generated from class definitions of the bean?
>
> ==========================================================================
> =
> 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".
