I found something interesting for KNX-Projects with a homeserver
This is a freeware KNX-Homeserver-Project.
Sorry, but this homepage is completely in german.
A large community has also created a big bunch of plugins for that project.
It works, I have tested it and I use this EDOMI-Homeserver.
For the administration you need a webkit-browser like google chrome.
And the best of all….
….. it is completely free and legal!