Define gRPC service used by Stub and Server. You should use Protobuf to to generate code instead of using this module directly.

It imports DSL functions like rpc/3 and stream/1 for defining the RPC functions easily:

defmodule Greeter.Service do
  use GRPC.Service, name: "helloworld.Greeter"

  rpc :SayHello, HelloRequest, stream(HelloReply)
end