db4o Developer Community

viabsb:Is it possible to develop a way for db4o write xml files and act with a xml native database like sedna or eXist or another one? The ideia is to have the registers in xml files. It would be possible to turn db4o into a pure XML database by writing a reflector layer that operates against XML. This would be a very nice community ...

In this session Rodrigo and Carl write a custom reflector with direct field access to be able to test the impact of reflection calls on the performance of db4o empirically. (Watch on-line without downloading here)

when working in a client server configuration is it requiered to have the customized reflector in the server class path ?   thanks   Yoram

tneward:jre/lib/ext isn't *just* for core JDK classes--far from it. Any extension library (and db4o marks a good candidate here) can be put there, such as scripting languages and the like.A optional package is an implementation of an open, standard API (examples of optional packages from Sun are JavaServlet, Java3D, JavaManagement). Most ...

final Configuration conf = Db4o.newConfiguration(); conf.reflectWith(new DummyReflector(Db4o.class.getClassLoader())); _db = Db4o.openFile(conf,fl.getAbsolutePath());DummyReflector is a copy of JdkReflector (I copied the whole package from db4o sources).For some reasons I cannot understand, as soon as I do ''config.reflectWith(...)'', it kills ...

Carl Rosenberger:If we try to be smarter about ClassLoaders, by finding the right one for each class, we would also make things easier for app server use. Can we solve this in a generic way? In principle we should have the required level of encapsulation in place already with the reflector layer. Perhaps it could already be sufficient to ...

Carl Rosenberger: Yes, this should work very nicely. Thanks! Good to know this is doable before getting knee deep! :) Carl Rosenberger: (1) We are not 100% happy with the way we delegate from the GenericReflector to the more specific platform reflector (JdkReflector / NetReflector / ''JamesPropertyReflector'' ). Ideally it should ...

Yes, this should work very nicely.   Three small caveats: (1) We are not 100% happy with the way we delegate from the GenericReflector to the more specific platform reflector (JdkReflector / NetReflector / ''JamesPropertyReflector'' ). Ideally it should be possible to have a longer chain of dependancies. (2) We still have some ...

montechristos:We use Aspect-Oriented Programming (or better, method interception with GCLIB) to inject some features in all the objects in our data model, without the data model knowing anything about it. So we keep the data model clean from (e.g. event dispatching, security). Certainly not an uncommon approach, I was just wondering why you ...

montechristos:Below is an example that doesn't call my LoggingReflector (only deepClone() is called). Oh, I see. :) You are using the ''global configuration''. Db4o.configure().reflectWith(new LoggingReflector());ObjectContainer db = Db4o.openFile(''Test.db'');Upon opening the file, the global config object is deep-cloned, and the clone is used ...