I am writing a server for playing the great diplomacy game online. Does anyone know an algorithm for the judge, that will calculate all moves/supports/convoys on the map at the end at each round?
For implementing the protocol I use twisted, for db-access django
Yes. DPjudge Adjudication Algorithm. Also see the DPJudge FAQ answer to the question about convoy paradoxes.
A check the njudge page that links to source code.