Hiran Chaudhuri wrote:
Hi, Thomas.
New to OBJ, I'm trying to decide whether to use it within my project as persistence layer or not. I have concerns since I read on http://db.apache.org/ojb/features.html that OQL support is incomplete, also there are some flaws in transaction handling.
Don't be too concerned. We only try to frankly state the truth. I know exactly one vendor with an 100% ODMG compliant OODBMS.
I don't know any 100% SQL92 compliant database.
With our oql implementation you can do everything that is needed to select persistent entities. Of you need special query functionality you may use PersistenceBroker queries inside ODMG applications. There is a seamless integration.
I don't know of any transaction handling problems with ODMG.
Now the bad question: Do you estimate the JDO api of OBJ is stable enough to
build a project onto that?
This is a question of how much risk you can afford. If you are willing to have some risks, yes.
Where could be pitfalls?
1. performance. The current OJB / JDO solution is a plugin to SUNs JDORI. They provide an interface to plugin different persistent store solutions. This interface does not provide an optimized query interface as the solution you find between OJB-ODMG and the OJB PersistenceBroker layer.
SO any queries that do a (non-primary key based) criteria lookup, will result in loading the complete extent (all instances of a given class) into memory an then filter all matching instances.
This is even worse than an full table scan in the DBMS!
With the current JDORI there are no ways to avoid this.
2. Testing. We have no regression testsuite for the JDO part yet. Of course all bug that we here of get fixed asap.
Or do you suggest to use the ODMG or even the PersistenceBroker APIs?
This really depends of the kind of project you want to run:
- For a small, innovatively minded, risk-tolerant project I'd use JDO.
- For a small, performance sensitive, minimum footprint solution I'd use PersistenceBroker
- For a big enterprise level, prime time app I'd still use ODMG.
just my 0.02 EUR,
Thomas
Hiran
----- Original Message ----- From: "Mahler Thomas" <[EMAIL PROTECTED]> To: "'OJB Users List'" <[EMAIL PROTECTED]> Sent: Wednesday, February 19, 2003 5:32 PM Subject: AW: JDO
Hi Lennart,
By using SUNs JDORI and the OJB OjbStore Plugin (See tutorial4.html for details) you have a fully compliant JDO solution today!
We want to have a full replacement of the upper JDORI layers for OJB 2.0. This implementation will add no functionality but only have non-functional improvements (performance, resource consumption). There is no time schedule for this release yet.
cheers, Thomas
-----Urspr�ngliche Nachricht----- Von: Lennart Benoot [mailto:[EMAIL PROTECTED] Gesendet: Mittwoch, 19. Februar 2003 14:44 An: [EMAIL PROTECTED] Betreff: JDO
Hey All,
Is there a date set forward when OJB will fully support JDO?
Regards, Lennart
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