Midgard2 is an Open Source Content Repository. 
It provides an object-oriented and replicated environment for building 
data-intensive applications for both web and the desktop.

With Midgard2 you have generic way to define your own storage objects, 
that can then be queried and managed using multiple programming languages 
and applications. This enables writing your CMS or project management tool 
using a repository-oriented architecture where the Midgard2 storage system 
acts as the central point of integration between various tools.

Midgard2 is built on the GNOME stack of libraries like GLib and libgda, 
and has language bindings for C, Objective-C, Python and PHP. 
Communications between applications written in the different languages happen over D-Bus.

http://midgard2.org