To get state of any process in erlang/elixir use :sys.get_state/1

By name:

:sys.get_state(MyGenServer)

By pid:

:sys.get_state(pid)

To make service discoverable we need following services registered:

[
  # create domain for an ip
  %Mdns.Server.Service{domain: "somedomain.local", data: :ip, ttl: 450, type: :a},

  # make service discoverable
  %Mdns.Server.Service{domain: "_services._dns-sd._udp.local",data: "_ssh._tcp.local",ttl: 4500, type: :ptr},

  # register ssh service
  %Mdns.Server.Service{domain: "_ssh._tcp.local",data: "SOME NAME._ssh._tcp.local",ttl: 4500, type: :ptr},

  # point service to our domain and port (22)
  %Mdns.Server.Service{domain: "SOME NAME._ssh._tcp.local",data: {0,0,22, 'somedomain.local'},ttl: 4500,type: :srv},

  # empty txt service (some tools expext that)
  %Mdns.Server.Service{domain: "SOME NAME._ssh._tcp.local",data: [],ttl: 4500,type: :txt})
] |> Enum.each(&Mdns.Server.add_service/1)

If you need a pubsub, to connect LiveViews for example just use YourAppWeb.Endpoint.

YourAppWeb.Endpoint.subscribe("topic")

YourAppWeb.Endpoint.broadcast("topic", "event", %{data: "data"})

def handle_info(%{event: "event", topic: "topic", payload: payload}) do
  # Do whatever you want
end

Just type: [enter]~.

Yes, Enter, tilde and dot!