How to Use gRPC in Microservices: A Simple Guide for Beginners

When you build microservices, you’re creating multiple small applications that talk to each other — like teammates working on the same project.

But how do these services communicate efficiently?
That’s where gRPC comes in.

Let’s break it down step-by-step in simple terms.

What is gRPC?

gRPC (Google Remote Procedure Call) is a high-performance, open-source framework created by Google.
It allows different microservices — even if written in different programming languages — to communicate seamlessly.

Think of gRPC as the high-speed language that connects all your microservices together.

gRPC helps services talk faster, smaller, and smarter.

Why gRPC is Perfect for Microservices

In a microservice architecture, each service does one small job — like:

• Authentication
• Payments
• Notifications
• Data storage

These services constantly send data to one another.

Using REST APIs for this works, but it’s often slow and chatty, since REST uses:

• HTTP/1.1 (one request at a time)
• JSON, which is large in size

Now, enter gRPC:

So, gRPC is like the fiber-optic cable of microservices — fast, compact, and bidirectional.

The 4 Types of gRPC Communication in Microservices

gRPC defines four ways for services to exchange data — called RPC methods:

1. Unary RPC
   → One request, one response
   Example: A User service asking an Auth service for login validation. rpc ValidateUser (UserRequest) returns (UserResponse);
2. Server Streaming RPC
   → Client sends one request, server sends a stream of data
   Example: A Dashboard service fetching a live list of transactions.
3. Client Streaming RPC
   → Client sends multiple requests, server responds once
   Example: Uploading multiple files from a File service.
4. Bidirectional Streaming RPC
   → Both client and server send continuous data
   Example: A Chat service sending and receiving live messages.

How to Use gRPC in Microservices (Step-by-Step Example)

Let’s say you’re building two microservices:
User Service and Auth Service.

You’ll use gRPC so they can communicate quickly.

Step 1: Install gRPC

For Python:

pip install grpcio grpcio-tools

Step 2: Define Communication Rules (auth.proto)

This .proto file defines the structure of requests and responses between your services.

syntax = "proto3";

service AuthService {
  rpc ValidateUser (AuthRequest) returns (AuthReply);
}

message AuthRequest {
  string username = 1;
  string password = 2;
}

message AuthReply {
  bool is_valid = 1;
  string message = 2;
}

Step 3: Generate gRPC Code

python -m grpc_tools.protoc -I. --python_out=. --grpc_python_out=. auth.proto

Step 4: Create the Auth Service (Server)

from concurrent import futures
import grpc, auth_pb2, auth_pb2_grpc

class AuthService(auth_pb2_grpc.AuthServiceServicer):
    def ValidateUser(self, request, context):
        if request.username == "admin" and request.password == "1234":
            return auth_pb2.AuthReply(is_valid=True, message="User validated")
        return auth_pb2.AuthReply(is_valid=False, message="Invalid credentials")

server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
auth_pb2_grpc.add_AuthServiceServicer_to_server(AuthService(), server)
server.add_insecure_port('[::]:50051')
server.start()
server.wait_for_termination()

Step 5: Create the User Service (Client)

import grpc, auth_pb2, auth_pb2_grpc

channel = grpc.insecure_channel('localhost:50051')
stub = auth_pb2_grpc.AuthServiceStub(channel)

response = stub.ValidateUser(auth_pb2.AuthRequest(username="admin", password="1234"))
print(response.message)

✅ Output:

User validated

Why Microservices Love gRPC

• Faster communication: Binary format (protobuf) beats JSON.
• Strong typing: No guessing field names — structure is clearly defined.
• Streaming: Real-time updates between services.
• Cross-language support: Works across Go, Java, Python, Node.js, C#, etc.
• Scalable: Ideal for large distributed systems.

In short:

gRPC makes microservices communicate like a Formula 1 team — fast, efficient, and perfectly in sync.

Final Thoughts

If you’re building microservices, you need fast, reliable communication between services — and that’s exactly what gRPC provides.

With HTTP/2, protocol buffers, and streaming support, gRPC turns your architecture into a high-performance, real-time system.

So next time you design a microservice, skip the REST bottleneck —
and let gRPC do the talking.

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