问python grpc 从proto文件中生成的两个pb文件的问题 pb没有proto定义的服务？

syntax = "proto3";

// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}

python -m grpc_tools -I ./ --python_out=./ --grpc_python_out=. ./helloworld.proto

# -*- coding: utf-8 -*-
# Generated by the protocol buffer compiler.  DO NOT EDIT!
# source: helloworld.proto
"""Generated protocol buffer code."""
from google.protobuf.internal import builder as _builder
from google.protobuf import descriptor as _descriptor
from google.protobuf import descriptor_pool as _descriptor_pool
from google.protobuf import symbol_database as _symbol_database
# @@protoc_insertion_point(imports)

_sym_db = _symbol_database.Default()




DESCRIPTOR = _descriptor_pool.Default().AddSerializedFile(b'\n\x10helloworld.proto\"\x1c\n\x0cHelloRequest\x12\x0c\n\x04name\x18\x01 \x01(\t\"\x1d\n\nHelloReply\x12\x0f\n\x07message\x18\x01 \x01(\t23\n\x07Greeter\x12(\n\x08SayHello\x12\r.HelloRequest\x1a\x0b.HelloReply\"\x00\x62\x06proto3')

_builder.BuildMessageAndEnumDescriptors(DESCRIPTOR, globals())
_builder.BuildTopDescriptorsAndMessages(DESCRIPTOR, 'helloworld_pb2', globals())
if _descriptor._USE_C_DESCRIPTORS == False:

  DESCRIPTOR._options = None
  _HELLOREQUEST._serialized_start=20
  _HELLOREQUEST._serialized_end=48
  _HELLOREPLY._serialized_start=50
  _HELLOREPLY._serialized_end=79
  _GREETER._serialized_start=81
  _GREETER._serialized_end=132
# @@protoc_insertion_point(module_scope)

# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
"""Client and server classes corresponding to protobuf-defined services."""
import grpc

import helloworld_pb2 as helloworld__pb2


class GreeterStub(object):
    """The greeting service definition.
    """

    def __init__(self, channel):
        """Constructor.

        Args:
            channel: A grpc.Channel.
        """
        self.SayHello = channel.unary_unary(
                '/Greeter/SayHello',
                request_serializer=helloworld__pb2.HelloRequest.SerializeToString,
                response_deserializer=helloworld__pb2.HelloReply.FromString,
                )


class GreeterServicer(object):
    """The greeting service definition.
    """

    def SayHello(self, request, context):
        """Sends a greeting
        """
        context.set_code(grpc.StatusCode.UNIMPLEMENTED)
        context.set_details('Method not implemented!')
        raise NotImplementedError('Method not implemented!')


def add_GreeterServicer_to_server(servicer, server):
    rpc_method_handlers = {
            'SayHello': grpc.unary_unary_rpc_method_handler(
                    servicer.SayHello,
                    request_deserializer=helloworld__pb2.HelloRequest.FromString,
                    response_serializer=helloworld__pb2.HelloReply.SerializeToString,
            ),
    }
    generic_handler = grpc.method_handlers_generic_handler(
            'Greeter', rpc_method_handlers)
    server.add_generic_rpc_handlers((generic_handler,))


 # This class is part of an EXPERIMENTAL API.
class Greeter(object):
    """The greeting service definition.
    """

    @staticmethod
    def SayHello(request,
            target,
            options=(),
            channel_credentials=None,
            call_credentials=None,
            insecure=False,
            compression=None,
            wait_for_ready=None,
            timeout=None,
            metadata=None):
        return grpc.experimental.unary_unary(request, target, '/Greeter/SayHello',
            helloworld__pb2.HelloRequest.SerializeToString,
            helloworld__pb2.HelloReply.FromString,
            options, channel_credentials,
            insecure, call_credentials, compression, wait_for_ready, timeout, metadata)

# -*- coding: utf-8 -*-
# Generated by the protocol buffer compiler.  DO NOT EDIT!
# source: helloworld.proto
"""Generated protocol buffer code."""
from google.protobuf.internal import builder as _builder
from google.protobuf import descriptor as _descriptor
from google.protobuf import descriptor_pool as _descriptor_pool
from google.protobuf import symbol_database as _symbol_database
# @@protoc_insertion_point(imports)

_sym_db = _symbol_database.Default()




DESCRIPTOR = _descriptor_pool.Default().AddSerializedFile(b'\n\x10helloworld.proto\x12\nhelloworld\"\x1c\n\x0cHelloRequest\x12\x0c\n\x04name\x18\x01 \x01(\t\"\x1d\n\nHelloReply\x12\x0f\n\x07message\x18\x01 \x01(\t2I\n\x07Greeter\x12>\n\x08SayHello\x12\x18.helloworld.HelloRequest\x1a\x16.helloworld.HelloReply\"\x00\x42\x36\n\x1bio.grpc.examples.helloworldB\x0fHelloWorldProtoP\x01\xa2\x02\x03HLWb\x06proto3')

_builder.BuildMessageAndEnumDescriptors(DESCRIPTOR, globals())
_builder.BuildTopDescriptorsAndMessages(DESCRIPTOR, 'helloworld_pb2', globals())
if _descriptor._USE_C_DESCRIPTORS == False:

  DESCRIPTOR._options = None
  DESCRIPTOR._serialized_options = b'\n\033io.grpc.examples.helloworldB\017HelloWorldProtoP\001\242\002\003HLW'
  _HELLOREQUEST._serialized_start=32
  _HELLOREQUEST._serialized_end=60
  _HELLOREPLY._serialized_start=62
  _HELLOREPLY._serialized_end=91
  _GREETER._serialized_start=93
  _GREETER._serialized_end=166
# @@protoc_insertion_point(module_scope)

from google.protobuf import descriptor as _descriptor
from google.protobuf import message as _message
from typing import ClassVar as _ClassVar, Optional as _Optional

DESCRIPTOR: _descriptor.FileDescriptor

class HelloReply(_message.Message):
    __slots__ = ["message"]
    MESSAGE_FIELD_NUMBER: _ClassVar[int]
    message: str
    def __init__(self, message: _Optional[str] = ...) -> None: ...

class HelloRequest(_message.Message):
    __slots__ = ["name"]
    NAME_FIELD_NUMBER: _ClassVar[int]
    name: str
    def __init__(self, name: _Optional[str] = ...) -> None: ...