Be very careful using any kind of framework! While a framework can give you great benefits through reusable code, hiding implementation details and enforcing programming standards, the price you pay is performance. When you have a GUI framework, that is usually not a big problem, nobody will notice if the framework wastes a few milliseconds or even 10ths of seconds e.g. on some unnecessary redraws.
However, a database framework is a completely different issue. I worked with TopLink (for SmallTalk) in 1997-1999, and while I think it was very well designed, it did not scale very well. Take, for instance, lazy loading (that is, not instantiating/loading an object until you actually try to access the value of one of its attributes). In theory it's great , reducing queries to the database to a minimum. In real life it can be deadly: if, for instance, you wan't to display a list of n-persons and their adresses, a non-optimized TopLink (or any ejb container for that sake) will generate n+1 SQL statements. The first SQL statement gets all the person data and creates the person objects. Then your code iterates through these person objects and displays their name and addresses. However, every time you access the address of a new person in that loop, the framework/ejb container will generate and execute one SQL statement to retrieve that persons address! There are many ways to overcome this, but when it comes down to it, you have to decide if you want to learn java, jdbc and sql or if you want to learn java, jdbc, sql AND on top of that, a persistence framework. Don't get me wrong: I'm all for OO, but it is not a panacea: relational databases were designed for handling data. OO-languages, on the other hand, focus on making programming better and NOT on data. Regards Kim PS: At the end of the day, if you are too religious about it, you might end up a saint, but your surely will be forgotten. -----Urspr�ngliche Nachricht----- Von: Andy Bentley [mailto:[EMAIL PROTECTED]] Gesendet: Montag, 23. September 2002 17:43 An: JDJList Betreff: [jdjlist] Re: Platform Selection - Should I use J2EE+EJB? TopLink works great. Its been around for years. i.e. bugs have been worked out , production code !! The only thing to be said against it, is that in some N.I.H. orgs. it doesn't put the level of control directly into the developers hands. Personally I find it liberating to work on the business problems and not waste everyone's time with OO to Relation mappings. Tomm Carr wrote: > > Joseph Ottinger wrote: > > > For some reason, your question gives me the screaming meemies. The > > concept is correct - you'd use bean-managed persistence to access and > > manipulate (and persist) the data, and the latest EJB specs certainly > > support crossing individual entities... but the idea of adding high > > volume to "thousands of xml files" with "complex" in their > > description... I'm not sure you're going to GET high volume, no matter > > what you do. > > I agree. XML makes a very good low-end, transaction-free database. But > this seems to be have passed "low-end" quite a while ago. A good DBMS > is cheap, even Oracle. He seems to be pushing a technology way beyond > its abilities, therefore way beyond its usefulness. The word that came > to my mind when reading his description was "fragile." Which means > trouble, lots of it, and soon. > > For those who need high-powered persistence, but don't want to (or > can't) handle the conversion from object to relational, go to the Oracle > site and look for TopLink. It is free and looks very impressive. (I am > only just now examining it, but so far I like what I see.) > > Tomm > > To change your JDJList options, please visit: http://www.sys-con.com/java/list.cfm To change your JDJList options, please visit: http://www.sys-con.com/java/list.cfm To change your JDJList options, please visit: http://www.sys-con.com/java/list.cfm
