Now i wanted to try it with b4a and i think it partialy works, i get Success in sub JobDone,
but the message is:
{"jsonrpc":"2.0","error":{"code":-32700,"message":"Parse error"},"id":null}
Solved! I found the problem with help from this page: https://jsonformatter.curiousconcept.com/
The problem was the single ' instead of double quotes: ". I beleived, that both forms are able.