Implement XEP-0405: Mediated Information eXchange (MIX): Participant Server Requirements most likely as an extension of Roster processor (or even part of the roster processor and roster).
This can be considered finish - correct?
Implement XEP-0405: Mediated Information eXchange (MIX): Participant Server Requirements most likely as an extension of Roster processor (or even part of the roster processor and roster).