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InstantDB: [ANN] Object / Relational Mapping ObJectBridge 0.1.83 released


For those of you interested in Object - Relational Mappings:

I'd like to announce the newest release of ObJectBridge.
It's OpenSource, it's 100% Java, it's based on InstantDB.
See http://objectbridge.sourceforge.net for more infos.

>From the release notes:

ObJectBridge -- Bridging Java Objects and Relational Databases

ObJectBridge (OJB) provides transparent persistence
for Java Objects against relational databases.
It consists of a generic PersistenceBroker and an ODMG 3.0 compliant
transactional ObjectServer.
OJB uses an XML based dynamic Object - Relational Mapping. The mapping is
configurable on a per class basis and allows lazy materialization through
virtual proxies. OJB supports Bean Managed EntityBeans (BMP). It's
proxy- and caching-strategies allow performance enhancements for EJB
applications.

The 0.1.83 release of ObJectBridge includes the following modules:

broker   -- transparent persistence for Java Objects
server   -- ODMG 3.0 compliant Objectserver (work in progress)
test     -- JUnit regression tests and examples demonstrating programming
techniques
examples -- sample code demonstrating the API, (e.g. usage in EJB scenarios)

changes in this release:

New features:
- Support for user defined collections. It is now possible to use user
defined collections
  (e.g. typed collections) as Collection attributes. These collections must
  implement the interface ojb.broker.ManageableCollection to provide minimum
  interoperability with the PersistenceBroker mechanisms. There is a new
  TestClass test.ojb.broker.TypedCollectionTest testing and demonstrating
all
  relevant techniques.
- There is a first fully functional ODMG Collection:
  Dlist. It's implemented by ojb.server.collections.DListImpl. There is a
  TestClass test.ojb.odmg.DListTest testing and demonstrating the usage of
this
  collection.

changes, refactorings:
- Complete redesign of the ODMG Transaction-mechanism. I unified the
concepts of
  David's TransactionWrapper objects with my idea of ObjectModification
  objects, that had been responsible for different aspects of the
transaction
  management in OJB.
- Removed interface IPobject and baseclass Pobject. These
  were meant as examples for encapsulating PersistenceBroker code in
business
  objects. I don't want to encourage such a poor design any longer...
- Collection attributes can now be defined without reverse
ReferenceAttributes.
  This design was based on the wrong assumption, that there is always a
unique
  ReferenceAttribute describing the foreignkey relation betweeen the
involved
  tables. Now Collection Attributes can be defined without specifying an
  inverse reverse ReferenceAttribute. To make this possible it's now
necessary
  to specify the list of foreign key attributes (respectively their
Descriptor
  Ids) within the CollectionDescriptor.
- Harmonized the syntax for ReferenceDescriptors and CollectionsDescriptors
  in the repository.dtd. Now , ,  can
  be used in both classes. Usage of these tags is now optional. If
   is ommited, true is the default value. If ,
   default value is false.
bug fixes:
- storing of collection attributes did not work due to an error during the
  last refactoring. No JUnit test detected the error

  Thanks to Sascha Koenig for reporting this bug.

best regards,


Thomas


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