Re: [Objectbridge-jdo-dev] Non-JDBC data sources
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Re: [Objectbridge-jdo-dev] Non-JDBC data sources
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From: Juozas B. <ba...@ma...> - 2002-06-14 16:40:32
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Hi, I work on experimental persistence framework, it is Apache SimpleStore. It has implementation for JDBC, XMLDB and file. May be it is possible to merge both projects ? It is nothing bad to have two or more projects about the same, but I think it is good to find something the most usefull and reuse it. I prefer to have three or more projects at Apache : 1) Standard Apache DB API, only interfaces and "large" documentation. 2) Implementations and "small" documentation. JDO can be some kind of "standard" API, but it closed for people like me and I prefer Open Standards. Hi David, > -----Ursprüngliche Nachricht----- > Von: David Zejda [mailto:dv...@at...] > Gesendet: Donnerstag, 13. Juni 2002 01:17 > An: Obj...@li... > Betreff: [Objectbridge-jdo-dev] Non-JDBC data sources > > > I know, that OJB's focus sharpness (faq: It's concerned with > O/R mapping and > nothing else.) is design/manage advantage, but I work on > project, where it's > crucial to integrate disparate data sources (RDBMS, ODBMS, > XML based DBMS, > flat-files, vendor specific formats..). I decided not to use closed, > non-free solutions at all, so OJB (open-source, clearly designed, > scalable...), seems to be suitable as a persistency-heart. > Could you advise how to get on with OJB? > 1) use OJB as a single persistency adaptor, manage several ODMG > implementations, make some fascade to hide it, e.g. solve distributed > transactions...? If there are existing ODMG Java bindings to you other datasources this will be vers easy. Just write litte wrappers that route user request to different ODMG implementations. If there is no ODMG API for a given persistent store, you can implement a dedicated PersistenceBroker for this special persistent store. This way you can use the OJB ODMG (or JDO if you prefer) implementation to access arbitrary persistent stores. > 2) extent OJB (add persistency adpators to OJB) - if > publically useful, > release them under LGPL as modular OJB's parts/add-ons? Yes, that's what I'm recommending. have a look at our persistence kernel interface ojb.broker.PersistenceBroker. It contains no specifics for RDBMS. It is a generic abstractiion of an object store. There could be implementations for OODBMS, RDBMS, XML databases, file system or Directory Services ! You only have to provide a persistent store specific PersistenceBroker Implementation. Than you can use the OJB ODMG or JDO layer to work against those specific brokers. regarding OJB scope: As OJB will be one of the foundation projects of the new db.apache.org site, our scope is not longer limited as mentioned in the faq. OJB will be a generic object persistence integration platform! Thus having new PersistenceBroker implementations is very interesting for us! (especially XML, OODBMS, LDAP, flat-file) As we are moving to Jakarta, we will use the apache licence soon. > 2.1) is this posible without (negative) impact on OJB's actual design yes no problems! > 3) something else? > > In the roadmap there is (4me) a bit mysterious sentence "provide > distributed Meta-Object Protocol access through PersistenceBroker API" This has been implemented a long time ago. OJB comes with a client/server mode. To have fully operational clients it is necessary to have meta-data on the client too. This was not possible in the early days, but now it is. > Somewhere in OJB doc I read about possibility to build my own > PersistenceManager. Does it relate to mentioned problem? > No. You simply have to implement the PersistenceBroker interface to write a new storage adaptor. A persistenceManager would be something like your own ODMG or JDO implementation. That would be a much more difficult task! cheers, Thomas > Thanks for reply > David Zejda > > > PS: I know, I can suck all wanted info from API, but I thing, you (OJB > experts) can answer quickly and painlessly. > > BTW thanks for OJB, well done! > > > > > _______________________________________________________________ > > Don't miss the 2002 Sprint PCS Application Developer's Conference > August 25-28 in Las Vegas - > http://devcon.sprintpcs.com/adp/index.cfm?source=osdntextlink > > _______________________________________________ > Objectbridge-jdo-dev mailing list > Obj...@li... > https://lists.sourceforge.net/lists/listinfo/objectbridge-jdo-dev > _______________________________________________________________ Don't miss the 2002 Sprint PCS Application Developer's Conference August 25-28 in Las Vegas - http://devcon.sprintpcs.com/adp/index.cfm?source=dntextlink _______________________________________________ Objectbridge-jdo-dev mailing list Obj...@li... https://lists.sourceforge.net/lists/listinfo/objectbridge-jdo-dev |
