ZLand has the need for queries over entity beans, so we're building an
ODBC-EJB Bridge Driver with Simba. A JDBC based toolkit (SQL parser in a
driver skeleton) would have been nicer, but no one like Simba or Automation
Technology offers it yet. I expect performance will be poor, but everything
takes place between servers on a fast switch, not the internet, so it's
mitigated a bit. Can't wait for the EJS vendors to offer some of this
natively. It will be cool to run a big joining query (e.g. report) against
the driver, seeing the EJS get the data for the entity beans from several
different RDBMS's.
David
Chris Raber <[EMAIL PROTECTED]> on 05/07/99 11:13:43 AM
Please respond to A mailing list for Enterprise JavaBeans development
<[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
cc: (bcc: David Rauschenbach/ZLAND)
Subject Queries over EJB's, was RE: Granularity of
: EJBObjects
Eric writes:
> I'm a bit surprised that Chris from GemStone didn't mention
> queries over EJB objects; maybe in our various prototyping
> and development efforts we have not as yet reached the
> stage where such proven access paradigms are needed?
>
Could you elaborate please?
My thoughts on queries in general are:
- Depending on complexity, you might be well served by
direct SQL from session beans and batch returning of result
sets (the WL folks are promoters of this), OR
- If the "query" involves complex rules (object domain behavior)
you'll be traversing a graph (which could be an object graph
or finder's on entity beans...).
Either way, care must be taken not to return huge results sets
directly clients. And better to return a list of strings to display
with keys back to the objects they are from, than to return
remote entities from which text is then gotten to populate GUI
widgets, one entity at a time.
Curser behavior is usually need to scale, and this belongs in the
coarse grained interface of a session bean.
If you post some specific context we can drill down.
Regards,
-Chris.
----------------------------------------------------------------------
Chris Raber, Systems Engineer, GemStone Systems Inc.
100 West Big Beaver, Suite 200, Troy, MI 48084
phone: (248)-680-6691, fax: (248)-680-6689,
email: [EMAIL PROTECTED]
web: http://www.gemstone.com/
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