Understanding gRPC: Modern RPC Between Distributed Systems

Understanding gRPC and Its Modern Alternatives

gRPC (Google Remote Procedure Call) is a modern, high-performance framework for enabling remote communication between distributed systems. It brings the concept of RPC (Remote Procedure Call) into today’s multi-language, cloud-native, and real-time world.

🧠 What is RPC?

RPC allows a program to call a function on another machine just like it would call a local function. The complexity of network communication, serialization, and deserialization is abstracted away by the framework.

Traditional REST call:

GET /user?id=123

RPC-style call:

UserService.GetUser(123)

It looks and feels like a local method, but it’s executed remotely over the network.

📦 What is gRPC?

gRPC is Google’s open-source implementation of RPC, built on modern technologies:

• HTTP/2 for transport (fast, multiplexed)
• Protocol Buffers (Protobuf) for efficient, compact binary serialization
• Cross-language support and code generation
• Supports streaming, authentication, deadlines, and more

🛠 How gRPC Works Between Two Entities

1. Define the service in a .proto file using Protocol Buffers.
2. Generate client/server code using the gRPC compiler.
3. Client calls a method (e.g. GetUser()), and gRPC handles the communication.

Example .proto Definition:

service UserService {
  rpc GetUser (UserRequest) returns (UserResponse);
}

⚙️ gRPC vs. REST

Feature	gRPC	REST/HTTP
Transport Protocol	HTTP/2	HTTP/1.1
Serialization	Protobuf (binary, fast)	JSON (text, slower)
Streaming	✅ Bi-directional supported	❌ Not natively supported
Code Generation	✅ Automatic from .proto	❌ Manual client/server logic
Performance	🚀 High (low latency, compressed)	🐢 Slower (larger payloads)
Cross-language Support	✅ Excellent (many languages)	✅ But not automatically typed

🔁 gRPC Communication Flow

Here’s a simplified flow between a client and a server using gRPC:

• The client calls GetUser(123)
• gRPC serializes the request and sends it over HTTP/2
• The server receives the request, processes it, and returns a response
• The client receives the response as a native object

🧪 Real-World Use Cases

• Service-to-service communication in microservices
• Mobile/desktop client communicating with backend
• Streaming telemetry or real-time data feeds
• Performance-sensitive APIs replacing REST

✅ Summary

Concept	Explanation
RPC	A way to call functions across machines as if they're local
gRPC	A modern RPC framework by Google using Protobuf + HTTP/2
Use Case	Efficient, real-time, cross-language communication in distributed systems

🌍 Modern Alternatives to gRPC

Alternative	Transport	Serialization	Key Strengths
GraphQL	HTTP/1.1 or HTTP/2	JSON	Flexible queries, ideal for frontend/mobile, introspection
REST + JSON	HTTP/1.1	JSON	Simple, human-readable, widely adopted
tRPC	HTTP (Node.js)	TypeScript-native	Type-safe, no .proto, fast development for fullstack TypeScript
Apache Thrift	TCP/HTTP	Binary or JSON	Multi-language, customizable, supports different protocols
Cap’n Proto	TCP	Binary	Blazing fast, zero-copy, efficient for low-latency systems
JSON-RPC / XML-RPC	HTTP/TCP	JSON/XML	Simple, lightweight RPC for small systems
Connect (by Buf)	HTTP/1.1, 2, or 3	Protobuf or JSON	gRPC-compatible, browser-native, REST+gRPC+Connect in one

✅ How to Choose?

Use Case	Recommended Option
Frontend to backend (web/mobile)	GraphQL, Connect, REST
Polyglot microservices backend	gRPC, Connect, Thrift
Node.js fullstack TypeScript	tRPC
Ultra-fast or low-latency systems	Cap’n Proto
Simple, embedded/legacy systems	JSON-RPC