The IPB made as punbb through xml. The principle is the same as for the technical implementation does not know.
I have a question, which I am a complete zero, say, in modern script (joomla, wp, ipb, etc) supports extensions?
Personally I do not like how it is done in punbb, due to the fact that the support becomes hellish when a large amount. File manifesto that without illumination. This is where the idea of java? As far as it is justified?