gRPC Service Development

gRPC Service Development

Overview

Develop efficient gRPC services using Protocol Buffers for service definition, with support for unary calls, client streaming, server streaming, and bidirectional streaming patterns.

When to Use

• Building microservices that require high performance
• Defining service contracts with Protocol Buffers
• Implementing real-time bidirectional communication
• Creating internal service-to-service APIs
• Optimizing bandwidth-constrained environments
• Building polyglot service architectures

Instructions

1. Protocol Buffer Service Definition

syntax = "proto3";

package user.service;

message User {
  string id = 1;
  string email = 2;
  string first_name = 3;
  string last_name = 4;
  string role = 5;
  int64 created_at = 6;
  int64 updated_at = 7;
}

message CreateUserRequest {
  string email = 1;
  string first_name = 2;
  string last_name = 3;
  string role = 4;
}

message UpdateUserRequest {
  string id = 1;
  string email = 2;
  string first_name = 3;
  string last_name = 4;
}

message GetUserRequest {
  string id = 1;
}

message ListUsersRequest {
  int32 page = 1;
  int32 limit = 2;
}

message ListUsersResponse {
  repeated User users = 1;
  int32 total = 2;
  int32 page = 3;
}

message DeleteUserRequest {
  string id = 1;
}

message Empty {}

service UserService {
  rpc GetUser(GetUserRequest) returns (User);
  rpc ListUsers(ListUsersRequest) returns (ListUsersResponse);
  rpc CreateUser(CreateUserRequest) returns (User);
  rpc UpdateUser(UpdateUserRequest) returns (User);
  rpc DeleteUser(DeleteUserRequest) returns (Empty);
  rpc StreamUsers(Empty) returns (stream User);
  rpc BulkCreateUsers(stream CreateUserRequest) returns (ListUsersResponse);
}

message Event {
  string type = 1;
  string user_id = 2;
  string data = 3;
  int64 timestamp = 4;
}

service EventService {
  rpc Subscribe(Empty) returns (stream Event);
  rpc PublishEvent(Event) returns (Empty);
}

2. Node.js gRPC Server Implementation

const grpc = require('@grpc/​grpc-js');
const protoLoader = require('@grpc/​proto-loader');
const path = require('path');

const packageDef = protoLoader.loadSync(
  path.join(__dirname, 'user.proto'),
  { keepCase: true, longs: String, enums: String, defaults: true, oneofs: true }
);

const userProto = grpc.loadPackageDefinition(packageDef).user.service;

const users = new Map();
let userIdCounter = 1;

const userServiceImpl = {
  getUser: (call, callback) => {
    const user = users.get(call.request.id);
    if (!user) {
      return callback({ code: grpc.status.NOT_FOUND, details: 'User not found' });
    }
    callback(null, user);
  },

  listUsers: (call, callback) => {
    const page = call.request.page || 1;
    const limit = call.request.limit || 20;
    const offset = (page - 1) * limit;

    const userArray = Array.from(users.values());
    const paginatedUsers = userArray.slice(offset, offset + limit);

    callback(null, {
      users: paginatedUsers,
      total: userArray.length,
      page: page
    });
  },

  createUser: (call, callback) => {
    const id = String(userIdCounter++);
    const user = {
      id,
      email: call.request.email,
      first_name: call.request.first_name,
      last_name: call.request.last_name,
      role: call.request.role,
      created_at: Date.now(),
      updated_at: Date.now()
    };
    users.set(id, user);
    callback(null, user);
  },

  updateUser: (call, callback) => {
    const user = users.get(call.request.id);
    if (!user) {
      return callback({ code: grpc.status.NOT_FOUND, details: 'User not found' });
    }

    Object.assign(user, {
      email: call.request.email || user.email,
      first_name: call.request.first_name || user.first_name,
      last_name: call.request.last_name || user.last_name,
      updated_at: Date.now()
    });

    callback(null, user);
  },

  deleteUser: (call, callback) => {
    users.delete(call.request.id);
    callback(null, {});
  },

  streamUsers: (call) => {
    Array.from(users.values()).forEach(user => {
      call.write(user);
    });
    call.end();
  },

  bulkCreateUsers: (call, callback) => {
    const createdUsers = [];

    call.on('data', (request) => {
      const id = String(userIdCounter++);
      const user = {
        id,
        email: request.email,
        first_name: request.first_name,
        last_name: request.last_name,
        role: request.role,
        created_at: Date.now(),
        updated_at: Date.now()
      };
      users.set(id, user);
      createdUsers.push(user);
    });

    call.on('end', () => {
      callback(null, { users: createdUsers, total: createdUsers.length, page: 1 });
    });

    call.on('error', (err) => {
      callback(err);
    });
  }
};

const server = new grpc.Server();
server.addService(userProto.UserService.service, userServiceImpl);

server.bindAsync('0.0.0.0:50051', grpc.ServerCredentials.createInsecure(), () => {
  console.log('gRPC server running on port 50051');
  server.start();
});

3. Python gRPC Server (grpcio)

import grpc
from concurrent import futures
import user_pb2
import user_pb2_grpc
from datetime import datetime

class UserServicer(user_pb2_grpc.UserServiceServicer):
    def __init__(self):
        self.users = {}
        self.user_counter = 1

    def GetUser(self, request, context):
        if request.id not in self.users:
            context.set_code(grpc.StatusCode.NOT_FOUND)
            context.set_details('User not found')
            return user_pb2.User()
        return self.users[request.id]

    def ListUsers(self, request, context):
        users_list = list(self.users.values())
        page = request.page or 1
        limit = request.limit or 20
        offset = (page - 1) * limit

        return user_pb2.ListUsersResponse(
            users=users_list[offset:offset + limit],
            total=len(users_list),
            page=page
        )

    def CreateUser(self, request, context):
        user_id = str(self.user_counter)
        self.user_counter += 1

        user = user_pb2.User(
            id=user_id,
            email=request.email,
            first_name=request.first_name,
            last_name=request.last_name,
            role=request.role,
            created_at=int(datetime.now().timestamp()),
            updated_at=int(datetime.now().timestamp())
        )
        self.users[user_id] = user
        return user

    def StreamUsers(self, request, context):
        for user in self.users.values():
            yield user

    def BulkCreateUsers(self, request_iterator, context):
        created_users = []
        for request in request_iterator:
            user = self.CreateUser(request, context)
            created_users.append(user)

        return user_pb2.ListUsersResponse(
            users=created_users,
            total=len(created_users),
            page=1
        )

def serve():
    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
    user_pb2_grpc.add_UserServiceServicer_to_server(
        UserServicer(), server
    )
    server.add_insecure_port('[::]:50051')
    server.start()
    print('gRPC server running on port 50051')
    server.wait_for_termination()

if __name__ == '__main__':
    serve()

4. Client Implementation

const grpc = require('@grpc/​grpc-js');
const protoLoader = require('@grpc/​proto-loader');
const path = require('path');

const packageDef = protoLoader.loadSync(
  path.join(__dirname, 'user.proto')
);

const userProto = grpc.loadPackageDefinition(packageDef).user.service;
const client = new userProto.UserService('localhost:50051', grpc.credentials.createInsecure());

// Unary call
client.getUser({ id: '123' }, (err, user) => {
  if (err) console.error(err);
  console.log('User:', user);
});

// Server streaming
const stream = client.streamUsers({});
stream.on('data', (user) => {
  console.log('Received user:', user);
});
stream.on('end', () => {
  console.log('Stream ended');
});

// Client streaming
const writeStream = client.bulkCreateUsers((err, response) => {
  if (err) console.error(err);
  console.log('Created users:', response.users.length);
});

writeStream.write({ email: '[email protected]', first_name: 'John', last_name: 'Doe' });
writeStream.write({ email: '[email protected]', first_name: 'Jane', last_name: 'Smith' });
writeStream.end();

Best Practices

✅ DO

• Use clear message and service naming
• Implement proper error handling with gRPC status codes
• Add metadata for logging and tracing
• Version your protobuf definitions
• Use streaming for large datasets
• Implement timeouts and deadlines
• Monitor gRPC metrics

❌ DON'T

• Use gRPC for browser-based clients (use gRPC-Web)
• Expose sensitive data in proto definitions
• Create deeply nested messages
• Ignore error status codes
• Send uncompressed large payloads
• Skip security with TLS in production

Deployment

# Generate protobuf code
protoc --go_out=. --go-grpc_out=. *.proto

# Compile Node.js gRPC server
npm install @grpc/​grpc-js @grpc/​proto-loader

# Compile Python gRPC server
pip install grpcio grpcio-tools
python -m grpc_tools.protoc -I. --python_out=. --grpc_python_out=. user.proto