The source code is available in /src folder in your db4o distribution.
In .NET version the following projects are available:
Db4objects.Db4o
db4o core.
Db4objects.Db4o.Instrumentation
Bytecode instrumentation library
Db4objects.Db4o.NativeIo
Native IO adapter implementation
Db4objects.Db4o.NativeQueries
Native Query support library
Db4objects.Db4o.Tests
tests for db4o.
Db4oTutorial
db4o tutorial sources.
Db4oTool
db4o command-line utility. For a list of functions execute Db4oTool.exe without any arguments.
Db4oUnit
unit test framework for db4o.
Db4oUnit.Extensions
Db4oUnit extensions for testing db4o.
Working with the sources is very straightforward: you just need to open a solution file from Microsoft Visual studio. The sources are provided for Visual Studio 2003 and 2005, for desktop applications and Compact Framework.
Drs
db4o Replication System.
Further reading:
Building Java Versioncreate it
Building .NET Versioncreate it