Thanks for answer. I was not clear enough. I don’t want to setup a server to store documents. I just want simple collaboration, you know like two people to collaborate on the same document, possible to work in parallel.
For Calc I have found one solution (Tools | Share document): Collaboration - LibreOffice Help but it requires a shared directory which can be pain for non-computer-nerds.
So the Telepathy looks promising, you know two instant messaging clients communicating with each other. Probably simpler to configure. Hope some development gets on this topic.
P.S. I changed title of this thread to “non-Server Collaboration”.