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