> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Dain
> Sundstrom
> Sent: Tuesday, June 26, 2001 3:56 PM
> To: [EMAIL PROTECTED]
> Subject: Fw: [JBoss-dev] Shouldn't expose transaction-isolation within
> CMP
>
>
> Sorry, didn't get to to line right on this message, and it only went to
> marc... read below...
>
> -dain
>
> ----- Original Message -----
> From: "Dain Sundstrom" <[EMAIL PROTECTED]>
> To: "marc fleury" <[EMAIL PROTECTED]>
> Sent: Tuesday, June 26, 2001 2:24 PM
> Subject: Re: [JBoss-dev] Shouldn't expose transaction-isolation within CMP
>
>
> > > |Please correct me if I'm wrong(I seem to be wrong about 50% of the
> > > |time :-),
> > > |but, I really don't think you should expose transaction-isolation
> levels
> > > |within CMP or in the definition of entities. This really belongs in
> the
> > > |creation of the connection pool. CMP cannot really guarantee that a
> > > |connection will not be shared between different entity types
> > > |within the same
> > > |transaction that use the same connection pool. Actually, I'm pretty
> sure
> > >
> > > which is why I am asking if the jdbc drivers support
> reconfiguration of
> > the
> > > isolation level on the fly or is it pretty much a
> "constructor" thingy.
> > >
> > > btw if it is the good case (we can change it) then it is not up to
> minerva
> > > to do this, all minerva does is hand out the connection but
> it is up to
> a
> > > functional unit above it, one aware of the application accessing this
> > > connection. That would live in JCA, but it would need to know the
> > > applciation context, or it would purely live in the app server sphere
> > (i.e.
> > > jaws getting the connection, or asking the container to do it on its
> > behalf,
> > > whatever we can do that call somewhere, factored or not).
> > >
> > > am i making sense?
> > >
> >
> > I think I understand now. Here is some text I found the J2EE tutorial:
> >
> > ------------
> > You cannot modify the isolation level of a entity beans with
> > container-managed persistence. These beans use the default
> isolation level
> > of the DBMS, which is usually READ_COMMITTED. For entity beans with
> > bean-managed persistence and for all session beans, you can set the
> > isolation level programmatically with the API provided by the underlying
> > DBMS. A DBMS, for example, might allow you to permit
> uncommitted reads by
> > invoking the setTransactionIsolation method:
> >
> > Connection con;
> > ...
> > con.setTransactionIsolation(TRANSACTION_READ_UNCOMMITTED);
> >
> > Do not change the isolation level in the middle of a
> transaction. Usually,
> > such a change causes the DBMS software to issue an implicit commit.
> Because
> > the isolation levels offered by DBMS vendors may vary, you should check
> the
> > DBMS documentation for more information.
> > -----------
> >
> > So the code I added probably causes an "implicit commit," which is bad.
> > From my very JDBC centric perspective, this should be set in Minerva
> > (JBossPool?) and user configurable. I don't know much about the
> connector
> > architecture, so maybe Minerva is the wrong place.
> >
> > Any way, I think I should roll back my change. If you agree
> marc, just say
> > so and it is done.
> >
> > I don't know any thing about Minerva, so if you want that
> changed, someone
> > else would be better suited. If no one wants to do it, I'll look at it.
> >
> > -dain
> >
>
I know what to do for Minerva(aka org.jboss.pool.jdbc, correct?) and can put
these changes in. But I really wouldn't know what to do with JCA, that is,
if a change is required there as well.
Bill
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