In principle the db4o database file format is fully compatible between Java, .NET and Mono, no matter on which operating system db4o is run.

There is only a small difference between Java and the two .NET environments:
.NET class names also contain their assembly names. Accordingly all stored classes need to be renamed when a database file is to be ported from one system to the next. This can be fully automated generically, the renaming process is very fast.

Here is a running sample with a solution how generic rename code could look like. It demonstrates writing to a database file with Java, reading with .NET and vice versa: http://www.db4o.com/downloads/db4oJavaDotnet.zip

db4o 4.3 has been released as a "production" version today. This release includes all the changes in the development releases 4.1 and 4.2. The two most important new features stepping up from 4.0:
- Database file sizes of up to 254GB are possible
- Full support for all JDK 5 features is provided

New features in 4.3:

• File IO is pluggable
  To create your own file IO implementation, you simply have to inherit from the abstract class com.db4o.io.IoAdapter and implement all the abstract methods. We have included two demo implementations with the Java download:
  - a JNI implementation for Windows in /src/com/db4o/util/io/win32/
  - an NIO implementation in /src/com/db4o/util/io/NIOFileAdapter
  However these implementations are just intended as technical demonstrations, they have not been validated in heavy productive use. Here are some possible usecases why you may consider to write your own IoAdapter implementation:
  - achieve maximum performance with a native library for your platform
  - encrypt and decrypt slots with any fixed-length encryption mechanism of your choice
  - improve your security against hardware failures with a read-after-write check
  - mirror file IO to a redundant secondary or backup system
  
• We provide three new dedicated downloads for Mono for Unixes:
  - noarch.rpm (binary db4o.dll, no sources)
  - src.rpm (sources, no binary dll)
  - tar.gz (sources and binaries)
  
• In the .NET distribution the API documentation is now supplied as a Windows help file:
  /db4o-4.3/doc/api/db4o.chm
  
• In all Mono distributions the API documentation is now generated with NDoc instead of JavaDoc. The RPMs install the API documentation to /usr/share/doc/packages/db4o-4.3/api/index.html on SuSE and to /usr/share/doc/db4o-4.3/api/index.html on other distributions.
  

Enjoy!

Welcome to our new db4o product blogs!

On these pages we will:
- keep you up-to-date with the latest developments in, around and on top of db4o
- help you with occasional "Did you know?" postings
- crosspost the best knowhow from our newsgroup
- inform you about cool products with db4o
- keep you up-to-date about development trends that we consider important
- ... and more

Please help us with your feedback.

We want to make db4o exactly the way you want it to be.

Thank you!

Best,
Carl
--
Carl Rosenberger
Chief Software Architect
db4objects Inc.