Re: [INTERFACES] query java object?

Gotcha reply on the ejb list...

Cheers, very excited to look at this,

Joe Shevland.

----- Original Message -----
From: "Assaf Arkin" <arkin@exoffice.com>
To: "Joe Shevland" <shevlandj@kpi.com.au>
Cc: "Peter Mount" <petermount@it.maidstone.gov.uk>; "'Phillip Rhodes'"
<rhodespc@bellatlantic.net>; "'pgsql-interfaces@postgresql.org'"
<pgsql-interfaces@postgreSQL.org>
Sent: Thursday, January 06, 2000 4:28 PM
Subject: Re: [INTERFACES] query java object?


> Joe,
>
> Tomorrow we're going to release a new version of Castor that does just
> that. It's being developed and tests with PostgreSQL (what else) so you
> can bet it's PostgreSQL complaint.
>
> It does Java persistence into SQL tables by mapping Java fields to SQL
> columns, supports one-one and many-one relationships, inheritance,
> locking, the whole enchilada.
>
> This release only includes the ODMG API, the next release (two weeks
> from now) will include the CMP API as well (EJB 1.1 compliant) plus OQL
> for describing finders.
>
> The next release will also integrate with Tyrex for JTA transaction
> management, 2 phase commit, etc. I've been in contact with Peter about
> adding X/A support to the next release of the PostgreSQL JDBC driver to
> support distributed transactions.
>
> I'm doing the final touches on the source code right now and will have a
> release to download tomorrow.
>
> Oh, the link: http://castor.exolab.org
>
> arkin
>
>
> Joe Shevland wrote:
> >
> > Hi all,
> >
> > OK, hopefully this all makes sense...
> >
> > <background>
> > The enterprise java beans spec specifies that classes
> > requiring (CMP) persistence need to let the container know
> > which attributes to persist by way of an XML
> > descriptor.
> > </background>
> >
> > So, given that we only want to persist certain properties/attributes
> > of a particular Java class is this possible using the mechanism
> > described below?
> >
> > Also, what are the overheads involved here? I guess the table
> > will need to be created the first time an object of a particular
> > type is stored, after that it should fairly normal?
> >
> > I'd love to be able to come up with a container-managed-persistence
> > module based on PostgreSQL for EJBOSS (www.ejboss.org), but
> > I'm still sorting things out in my head as to the best ways of doing
this.
> >
> > One little weird one, given that the Java classes you persist actually
> > persist other classes they reference (as long as they're defined in
> > PostgreSQL mapping I guess), would a way around the cyclic
> > reference problem be to check the .equals() method when storing
> > chained objects, maintain a hashtable for each root node and not
> > store the object if it has already been done? That seems awfully
> > simplistic, what are the issues involved?
> >
> > Regards,
> > Joe.
> >
> > ----- Original Message -----
> > From: "Peter Mount" <petermount@it.maidstone.gov.uk>
> > To: "'Phillip Rhodes'" <rhodespc@bellatlantic.net>;
> > "'pgsql-interfaces@postgresql.org'" <pgsql-interfaces@postgreSQL.org>
> > Sent: Thursday, January 06, 2000 1:50 AM
> > Subject: RE: [INTERFACES] query java object?
> >
> > > Yes of sorts. We have a small extension that allows a Serialized
object
> > > to be stored in one or more tables (rather than as a stream). Once
> > > serialized in this way, you can then query the stored objects just
like
> > > any other SQL Table.
> > >
> > > Peter
> > >
> > > --
> > > Peter Mount
> > > Enterprise Support
> > > Maidstone Borough Council
> > > Any views stated are my own, and not those of Maidstone Borough
Council.
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: Phillip Rhodes [mailto:rhodespc@bellatlantic.net]
> > > Sent: Monday, January 03, 2000 2:11 AM
> > > To: 'pgsql-interfaces@postgresql.org'
> > > Subject: [INTERFACES] query java object?
> > >
> > >
> > > I read through the documentation for Postgres and Java, but I am a
> > > little
> > > unclear on something:  (probably a few things!)
> > >
> > > Is it possible to execute a query based on the attributes of a
> > > serialized
> > > object?  Or do I have to instantiate each object and do an if test?
> > >
> > >
> > > Thanks!
> > >
> > > Phillip
> > >
> > >
> > >
> > > ************
> > >
> > > ************
> > >
> >
> > ************
>