web之外的apis是如何工作的？

syntax = "proto3";

service Greeter {
    rpc SayHello (HelloRequest) returns (HelloReply) {}
}

message HelloRequest {
    string name = 1;
}

message HelloReply {
    string message = 1;
}

import grpc
from concurrent import futures
import hello_pb2
import hello_pb2_grpc

class Greeter(hello_pb2_grpc.GreeterServicer):
    def SayHello(self, request, context):
        return hello_pb2.HelloReply(message='Hello, %s!' % request.name)

def serve():
    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
    hello_pb2_grpc.add_GreeterServicer_to_server(Greeter(), server)
    server.add_insecure_port('[::]:50051')
    server.start()
    server.wait_for_termination()

if __name__ == '__main__':
    serve()

import grpc
import hello_pb2
import hello_pb2_grpc

def run():
    channel = grpc.insecure_channel('localhost:50051')
    stub = hello_pb2_grpc.GreeterStub(channel)
    response = stub.SayHello(hello_pb2.HelloRequest(name='World'))
    print("Greeter client received: " + response.message)

if __name__ == '__main__':
    run()