I should have thought of that - thanks. MOD
--- Mahler Thomas <[EMAIL PROTECTED]> wrote: > Here is some food for thought: > http://db.apache.org/ojb/links.html > > ;-) > Thomas > > > -----Original Message----- > > From: Michael Duffy [mailto:[EMAIL PROTECTED] > > Sent: Tuesday, April 01, 2003 6:30 PM > > To: OJB Users List; [EMAIL PROTECTED] > > Subject: Re: regression test errors > > > > > > > > Thank you, Thomas, I think I'll take your advice > and > > stick with PB API. For some reason, I thought you > > intended it as a lower layer API, with ODMG to be > > preferred. > > > > Later in this thread both you and Bonnie referred > to > > "all the usual suspects" for O/R mapping papers. > I've > > got copies of Scott Ambler's papers and one by > > Wolfgang Keller that is quite good. I've yet to > score > > a copy of Fowler's architecture patterns book. > What > > else would you recommend that someone read? What > are > > the papers "everyone knows" in this area? Thanks > in > > advance for the education. - MOD > > > > > > --- Thomas Mahler <[EMAIL PROTECTED]> wrote: > > > Hi again Michael, > > > > > > Michael Duffy wrote: > > > > Thanks to both Thomas and Armin for their > replies > > > on > > > > this thread. > > > > > > > > Speaking for myself, I'm nervous about using > OJB > > > on my > > > > current project, too, but I don't think the > source > > > is > > > > entirely OJB. A big part of it is fear of > what I > > > > DON'T know. I very much liked the idea of > using a > > > > tool, developed by folks more expert than me. > I > > > know > > > > enought about JDBC to be able to do CRUD > > > operations > > > > and simple transactions, but the idea of > having a > > > > layer to abstract all that out of business > objects > > > was > > > > appealing. > > > > > > > > I heard Martin Fowler talk a few months ago. > He > > > > mentioned using JAXOR as an O/R mapping tool. > > > When I > > > > looked into it, I found NO documentation > > > whatsoever. > > > > > > > > Google quickly turned up OJB as an > alternative. I > > > > liked it right away, because it had more > > > documentation > > > > than JAXOR, it the cachet of being a Jakarta > > > project, > > > > and the stuff that I did actually worked. Now > > > I've > > > > got a tree of four tables linked with m:n > > > > associations, all working in JUnit tests. > > > > > > > > All that's well and good, but now I'm nervous > > > about > > > > that learning curve and what I'm ignorant of. > > > I've > > > > done everything with the PersistenceBroker API > > > because > > > > it was easy to follow in the docs. But now > I'm > > > > thinking that I should really be doing all of > this > > > > using ODMG API instead. More learning, with a > > > > deadline approaching. > > > > > > choosing the actual OJB API is an important > > > decision. > > > > > > Why do you think you should use ODMG ? Do you > really > > > need Object level > > > transactions? > > > > > > If you plan to build your own persistence > Manager > > > layer with Data Access > > > Objects (DAO) (and possibly DTOs) you could be > > > better of with the PB API. > > > > > > The PB API gives you maximum flexibility and > nicely > > > fits into J2EE based > > > programming models. > > > > > > The ODMG API specification was designed as a > > > two-tier rich client API. > > > > > > > > > > > > > > Here's a fundamental question: > > > > > > > > RDBMS developers have put a lot of effort into > > > > maintaining referential integrity, managing > > > > transactions, etc. It seems to me that OJB is > > > taking > > > > over a lot of that stuff. When I created my > > > tables, I > > > > didn't add foreign key constraints. I left > all > > > that > > > > to OJB. The ODMG API will handle true > > > transactions > > > > and object/row locking. > > > > > > The OJB/ODMG does have pessimistic object level > > > locking. But it does not > > > provide DB row level locking! > > > > > > > > > > > But what if OJB isn't the only path into the > > > database? > > > > A DBA might balk at leaving all those things > that > > > the > > > > RDBMS would handle to OJB. Is it possible > still > > > leave > > > > foreign key constraints in the database so > others > > > > could use them without OJB? > > > > > > Yes! It's generally a good idea to let the DB > > > maintain data integrity as > > > much as possible. OJB was designed to work > smoothly > > > with existing databases. > > > The ODMG transaction manager also takes care not > to > > > conflict with > > > database foreign key constraints. > > > > > > If you want to sync OJB and non-OJB apps working > > > against the same db you > > > have to take care of at least two issues: > > > 1. Autoincremented Sequence Numbers. The Default > OJB > > > SequenceManager is > > > not aware of external processes. So you have to > use > > > a SequenceManager > > > implementation that uses database managed > sequence > > > numbers (or > > > Identies). There are several such > implementations in > > > the sequenceManager > > > package. > > > > > > 2. All processes working against the db should > use > > > optimistic locking to > > > avoid data disintegrity. OJB supports OL based > on > > > Version and timestamp > > > columns. > > > > > > > > > > > My compliments to Thomas, Armin, and the team > that > > > > created OJB. None of this fear is a > reflection on > > > > your excellent work. It has more to do with > the > > > fact > > > > that this is still a version 1.0 release > candidate > > > and > > > > my own ignorance. Sincerely, MOD > > > > > > thanks for the compliments, > > > cheers > > > Thomas > > > > > > > > > > > > > > > --- Thomas Mahler <[EMAIL PROTECTED]> wrote: > > > > > > > >>Hi Bonnie, > > > >> > > > >>Bonnie MacKellar wrote: > > > >> > > > >>>I was not at Mobius before 1999, so I really > > > would > > > >> > > > >>not know... > > > >> > > > >>>Yes, this is for an important project and I > am > > > not > > > >> > > > >>feeling > > > >> > > > >>>very good about this. The alternatives > though, > > > are > > > >> > > > >>to buy > > > >> > > > >>>something or do it ourselves. Our company > tends > > > to > > > >> > > > >>be of > > > >> > > > >>>the "do it yourself" mentality. Since what > we > > > >> > > > >>need is exactly > > > >> > > > >>>what OJB provides, it seems silly to > replicate > > > it. > > > >>>On the other hand, it is often easier to deal > > > with > > > >> > > > >>bugs > > > >> > > > >>>in your own code then with bugs in someone > else's > > > >> > > > >>code. > > > >> > > > >>OJB is 3 years of heavy designed code by > experts > > > in > > > >>the O/R area. > > > >>We have a complete regression testsuite that > > > covers > > > >>each and every > > > >>aspect of the system. > > > >> > > > >>Do it yourself is definitely a bad idea in > this > > > >>area. If you don't trust > > > >>us better use a commercial tool like TopLink. > > > >> > > > >>OJB is in production use in large projects for > 2 > > > >>years now. > > > >>My company is using OJB in several large and > > > mission > > > >>critical software > > > >>projects since a year now. > > > >> > > > >> > > > >>>I would feel a lot better about this if the > mail > > > >> > > > >>archives > > > >> > > > >>>worked. My usual approach with this kind of > > > system > > > >> > > > >>is > > > >> > > > >>>to really sift through user archives, looking > for > > > >> > > > >>similar > > > >> > > > >>>experiences. > > > >> > > > >>I admit this is really annoying. But this is > > > clearly > > > >>not an OJB problem, > > > >>but an infrastructure problem with some Apache > > > >>server. > > > >>For the time being use archive mirrors at > GMANE or > > > >>at > > > >> > > > > > > > > > > > > > > http://www.mail-archive.com/ojb-user%40db.apache.org/ > > > > > > > >>cheers, > > > >>Thomas > > > >> > > > >> > > > >>>Bonnie > > > >>> > > > >>>-----Original Message----- > > > >>>From: Michael Duffy > [mailto:[EMAIL PROTECTED] > > > >>>Sent: Friday, March 28, 2003 1:19 PM > > > >>>To: OJB Users List > > > >>>Subject: RE: regression test errors > > > >>> > > > >>> > > > >>> > > > >>>Bonnie, > > > >>> > > > >>>I'm responding to a note you sent to the OJB > > > >> > > > >>mailing > > > >> > > > >>>list. > > > >>> > > > >>>Is Mobius based in the NYC area? I knew a > guy > > > >> > > > >>named > > > >> > > > >>>Howard Deiner who worked at a company named > > > >> > > > >>Mobius. > > > >> > > > >>>His tenure would have been prior to 1999. > Just > > > >>>curious. > > > >>> > > > >>>Also curious - will the system you'll be > > > >> > > > >>installing > > > >> > > > >>>OJB into be a large production application? > I've > > > >> > > > >>been > > > >> > > > >>>getting OJB up and running for a smaller > > > >> > > > >>production > > > >> > > > >>>project, and I'm nervous about it. I see all > the > > > >>>problems on the mailing list and sketchy > > > >> > > > >>documentation > > > >> > > > >>>and wonder what I'm getting myself into. > JMHO, > > > of > > > >>>course. Are you feeling the same way? > Thanks - > > > >> > > > >>MOD > > > >> > > > >>> > > > >>>--- Bonnie MacKellar <[EMAIL PROTECTED]> > wrote: > > > >>> > > > >>> > > > >>>>Thanks for the advice. > > > >>>>This parameter is set in > > > >>>> > > > >>> > > > >>> > > > > > > > > > > C:\db-ojb-1.0.rc1\target\test\ojb\repository_database.xml, > > > > > > > >>>>right? Do I need to change anything else to > > > modify > > > >>>>this behavior? > > > >>>> > > > >>>>I'm still trying to feel my way around this > > > >>> > > > >>system. > > > >> > > > >>>>Basically, I have > > > >>>>about a week to make a recommendation on > using > > > it, > > > >>>>in a large project. > > > >>>>Ease of use is an important consideration, > > > >>>>especially to the powers-that-be > > > >>>>who are managing this project. > > > >>>> > > > >>>>Bonnie > > > >>>> > > > >>>>-----Original Message----- > > > >>>>From: Armin Waibel > > > >>>>[mailto:[EMAIL PROTECTED] > > > >>>>Sent: Wednesday, March 26, 2003 6:42 PM > > > >>>>To: OJB Users List > > > >>>>Subject: Re: regression test errors > > > >>>> > > > >>>>Seems a problem with the used sequence > manager > > > >>>>(SequenceManagerHighLowImpl). > > > >>>>Try to run the test cases with > > > >>>>SequenceManagerInMemoryImpl > > > >>>>Do you get the same results? > > > >>>> > > > >>>> > > > >>> > > > >>> > > > >>> > > > > > > >>>__________________________________________________ > > > >>>Do you Yahoo!? > > > >>>Yahoo! Platinum - Watch CBS' NCAA March > Madness, > > > >> > > > >>live on your desktop! > > > >> > > > >>>http://platinum.yahoo.com > > > >>> > > > >>> > > > >> > > > > > > > > > > --------------------------------------------------------------------- > > > > > > > >>>To unsubscribe, e-mail: > > > >> > > > >>[EMAIL PROTECTED] > > > >> > > > >>>For additional commands, e-mail: > > > >> > > > >>[EMAIL PROTECTED] > > > >> > > > >> > > > >> > > > >> > > > > > > > > > > --------------------------------------------------------------------- > > > > > > > >>To unsubscribe, e-mail: > > > >>[EMAIL PROTECTED] > > > >>For additional commands, e-mail: > > > >>[EMAIL PROTECTED] > > > >> > > > > > > > > > > > > > > > > > __________________________________________________ > > > > Do you Yahoo!? > > > > Yahoo! Platinum - Watch CBS' NCAA March > Madness, > > > live on your desktop! > > > > http://platinum.yahoo.com > > > > > > > > > > > > > > --------------------------------------------------------------------- > > > > To unsubscribe, e-mail: > > > [EMAIL PROTECTED] > > > > For additional commands, e-mail: > > > [EMAIL PROTECTED] > > > > > > > > > > > > > > > > > > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: > > > [EMAIL PROTECTED] > > > For additional commands, e-mail: > > > [EMAIL PROTECTED] > > > > > > > > > __________________________________________________ > > Do you Yahoo!? > > Yahoo! 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