Since wer'e advertising decent CMP implementations, I will add:
<vendor>
Selective updates are provided by Sybase EAServer, thereby
preventing database corrupting when using OC. This feature is
provided for EJB 1.1 today, and will also exist in our EJB 2.0 /
J2EE 1.3 product, out when the specs are completed.
</vendor>
"Jonathan K. Weedon" wrote:
>
> Cedric,
>
> As you say, supporting optimistic concurrency via the database is
> easy for an appserver to do.
>
> However, as you also say, you need to do selective updates, to
> ensure that you don't "overwrite data written externally since the
> transaction was begun."
>
> Is such a feature provided in WL6 using EJB 1.1? I did not
> believe so.
>
> In which case, in WL using EJB 1.1, WebLogic will corrupt the database,
> if you use optimistic concurrency. (Note that OC cannot be avoided
> when clustering.)
>
> Is this a valid statement?
>
> <vendor>
> Selective updates are provided by Borland AppServer, thereby
> preventing database corrupting when using OC. This feature is
> provided for EJB 1.1 today, and will also exist in our EJB 2.0 /
> J2EE 1.3 product, out when the specs are completed.
> </vendor>
>
> -jkw
>
> Cedric Beust wrote:
>
> > > From: A mailing list for Enterprise JavaBeans development
> > > [mailto:[EMAIL PROTECTED]]On Behalf Of Peter Verkest
> >
> > > Optimistic locking at the container would be great indeed, but
> > > how about optimistic locking at the DB level?
> >
> > Most of the databases already offer this (starting with Oracle). It's the
> > easiest option for an EJB container provider, we have almost nothing to do
> > :-)
> >
> > > If we are working in a cluster with n nodes, is there any need to
> > > ejbLoad an entity more than once per transaction then?
> >
> > No, but in the case of optimistic concurrency at the container level, a
> > check will be needed when the transaction commits to make sure the UPDATE
> > won't overwrite data written externally since the transaction was begun.
> >
> > --
> > Cedric
>
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--
________________________________________________________________________________
Evan Ireland Sybase EAServer Engineering [EMAIL PROTECTED]
Wellington, New Zealand +64 4 934-5856
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