I disagree with your statement of "Let's face it, O/R mappings will never be very efficient. " Both OJB (to which I contribute) and Hibernate (which I watch closely) approximate raw JDBC performance in most cases, and can exceed it in many others. Go check out the performance target in OJB, and Hibernate documentation goes over performance extensively. Both are GREAT projects, but neither is CMP. cheers, Matthew -----Original Message----- From: Pete Beck [mailto:[EMAIL PROTECTED]] Sent: Wed 1/8/2003 12:04 PM To: [EMAIL PROTECTED] Cc: Subject: Re: [JBoss-user] Cmp vs hibernate A common usage for CMP entity beans seems to be for persistent objects using an O/R mapping. Although entity beans can generally act that way, that is by no means all they amount to. In fact Sun have a more light-weight spec for this purpose (JDO). I can't help feeling that hybernate is nearer to JDO than to EJB. IMHO, CMP beans are more like abstract components (or black boxes if you like) than persistent objects. This is why they have all the interfaces. They were designed to be accessed over RMI and act more as service providers than as discrete objects. An entity bean abstraction can be very complex and span many objects. The are designed to be scalable so that if they are very complex, they do not need to reside permanently in memory although give their clients the illusion that they are. Of course, these principles were developed when memory was a lot more of a problem than it is today. The CMP part is actually an implementation detail and the O/R mapping even more so. Hence performance issues can never be blamed on CMP, but rather on their implementations. Let's face it, O/R mappings will never be very efficient. For CMP to realise its full potential there needs to be a new feature rich database technology developed that is optimised specifically for EJB, and provides CMP functionality natively. In fact that sounds like it would be a pretty cool project. :-) On Wed, 2003-01-08 at 18:24, [EMAIL PROTECTED] wrote: > We are missing support for SUM and COUNT sql-function as well as > subqueries in CMP, which hibernate have. This has forced us into using > pure sql for this part to get it reasonable fast. > > Also you don't need all dataobjects and interfaces in hibernate, so we > should try it soon, nut it would be nice too see a performance comparison with CMP, hibernate, JDO and OJB. We are not satisfied with whe performance of CMP and only pure SQL had probably have been faster (although jboss is supposed to have cache). -- Peter Beck BEng (hons) - Managing Director, Electrostrata Ltd. http://www.electrostrata.com --+-+-- Experts in e-business and e-commerce ------------------------------------------------------- This SF.NET email is sponsored by: SourceForge Enterprise Edition + IBM + LinuxWorld = Something 2 See! http://www.vasoftware.com _______________________________________________ JBoss-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/jboss-user
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