Questions

How to start a server manually?

Just use Service.listen() method without forever flag. You can start as many servers on different ports as you want:

import asyncio
from interest import Service

service = Service()
server1 = service.listen(host='127.0.0.1', port=9001)
server2 = service.listen(host='127.0.0.1', port=9002)
try:
    service.loop.run_forever()
except KeyboardInterrupt:
    pass