Hi!
Aaron Mulder wrote:
> On Mon, 22 May 2000, Rickard [iso-8859-1] �berg wrote:
> > Hold on!!! You have used a *connection* (a pipe, something to send stuff
> > through, but *not* a data storage) to execute queries. All that data has
> > been sent to the database. The data is *not* tied to the connection as
> > such, it is tied to the *tx*. The connection is just a pipe we use to
> > shuffle our stuff through.
>
> I wasn't aware you could distinguish between a connection and a
> transaction in JDBC. But perhaps this is what you meant when you talked
> about 2.0 drivers.
Exactly. In JDBC 1.0 con's and tx's are tied very strongly to each
other. Now, with the XAResource thing this coupling is much more loose.
> So you're saying that with a "2.0" driver, the DBMS
> vendor implements XAResources and XAConnections within their driver, so
> we don't deal directly with the connections or transactions - they handle
> it all for us. Magical!
Right on :-)
> I went back and looked at the Oracle drivers, and discovered that
> that latest drivers do indeed support this - they provide an XADataSource.
> That sures saves a bundle of work! NOW we're on the same page!
Yep, that saves a LOT of work :-)
> However, this simply raises a new and different set of questions.
> Sigh.
>
> 1) How many drivers implement this? I suspect not too many, but I'd love
> ot be surprised.
Exactly, which is why I proposed a JDBC1.0 driver wrapper that makes any
non-2.0 driver appear as though it was 2.0. Of course, it will always
fail on "prepare" and "commit" (since JDBC 1.0 is 1-phase only!), so the
tx-manager will have to make sure to use the 1-phase optimization if
possible.
> 2) Unfortunately, the DataSource interface does not include any methods
> for configuring the DataSource. That is, there's no standard way to
> specify the server, port, instance/database, URL, etc. The spec suggests
> that the implementation be beany (get/set for all properties), but only
> "suggests" the properties. So how do we allow configuration? I suppose
> we can take a property list and try to invoke an appropriate setXXX method
> for each proparty via reflection, and error out if we can't find an
> appropriate method...
Exactly.
> 3) What do we do with drivers that don't implement this? I think we may
> have the same intention here, which is to create a wrapper for 1.0 drivers
> where we implement all the XA stuff and prevent bad things from happening.
See above. Yes. Non-trivial, but the only way to go IMHO.
/Rickard
--
Rickard �berg
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