Dart: about grpc (I)

Write it at the front

Recently I learned that gRPC Related content of , This article is about usage and concepts , With Dart Language as a code example .

Content

Start with an example

Configuration environment

1. install Dart SDK or Flutter SDK, Then configure their environment variables
2. install protobuf
   • brew install protobuf
3. install protoc_plugin
   • pub global activate protoc_plugin
   • stay bash_profile （M1 It should be zshrc in ） Add below export PATH="$PATH":"$HOME/.pub-cache/bin"
4. I'm using IDEA Development , You can install one called Protocol Buffer Editor Plug in for , To help us edit better .proto file .

Demo

Let's build a new Dart engineering , In its pusepc.yaml Add dependency ：

dependencies:
  protobuf: ^2.0.0
  grpc: ^3.0.0

Then we can start .

stay lib Create under folder protos （ Name at will ） Folder , Then create helloworld.proto Used to write our code ：

// helloworld.proto
syntax = "proto3";

package helloworld;

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

message HelloRequest{
  string name = 1;
}

message HelloReply{
  string message = 1;
}

At the beginning, we declared that proto3 edition , And then defined Greeter service , And declared a rpc Interface SayHello, The requested parameter is HelloRequest, The returned parameter is HelloReply.

stay lib Under the table of contents , We build a new one src/generated Folder , It is used to store the files we will generate later .

Then the command line enters our lib Under the table of contents , Carry out orders ：

protoc --dart_out=grpc:src/generated -Iprotos protos/helloworld.proto

such generated The corresponding file will be generated under the folder ：

helloworld.pbjson.dart
helloworld.pbgrpc.dart
helloworld.pbenum.dart
helloworld.pb.dart

It's the same in lib Under the directory, we create src/bin Directory to write our client and server .

client ：

// client.dart
import 'package:grpc/grpc.dart';
import 'package:grpc_learning/src/generated/helloworld.pbgrpc.dart';

void main() async {
  final channel = ClientChannel(
    'localhost',
    port: 50051,
    options: ChannelOptions(
      credentials: ChannelCredentials.insecure(),
      codecRegistry:
          CodecRegistry(codecs: const [GzipCodec(), IdentityCodec()]),
    ),
  );
  final stub = GreeterClient(channel);

  final name = 'world';

  try {
    final response = await stub.sayHello(HelloRequest()..name = name);
    print('Greeter client received: ${response.message}');
  } catch (e) {
    print('error  = ${e.toString()}');
  }
  await channel.shutdown();
}

Server side ：

// server.dart
import 'package:grpc/grpc.dart';
import 'package:grpc/src/server/call.dart';
import 'package:grpc_learning/src/generated/helloworld.pbgrpc.dart';

class GreeterService extends GreeterServiceBase {
  @override
  Future<HelloReply> sayHello(ServiceCall call, HelloRequest request) async {
    return HelloReply()..message = 'I got it ${request.name}';
  }
}

void main() async {
  final server = Server([GreeterService()]);
  await server.serve(port: 50051);
  print('Server listening on port ${server.port}...');
}

Next, we can start two terminals , To run the client and server respectively , Use dart server.dart and dart client.dart To execute .
Execution results ：

//  Server side 
Server listening on port 50051...

//  client 
Greeter client received: I got it world

This completes a gRPC The client communicates with the server Demo.

Reference resources

Dart : Quick start