A Complete Guide of RPC (Remote Procedure Call)

What is RPC (Remote Procedure Call)?

🔹 What is RPC (Remote Procedure Call)?

Remote Procedure Call (RPC) is a protocol that allows a computer program to execute a function or procedure on another computer (remote server) as if it were a local function.

✅ Key Idea: RPC enables communication between different processes across a network or within the same system.
✅ Used In: Microservices, Distributed Systems, API Communication, Cloud Computing.

🔹 How Does RPC Work?

1️⃣ Client sends a request → Calls a function on a remote server.
2️⃣ Server processes the request → Executes the function.
3️⃣ Server sends a response → Returns the output to the client.

📌 Example of RPC Flow:

Client App  ── Request (RPC Call) ──> Remote Server  
Remote Server  ── Process & Execute ──> Send Response  
Client App  ── Receive & Process Response ──> Done ✅

🔹 Types of RPC

1️⃣ Synchronous RPC

• Client waits for the server to respond before continuing.
• Example: Traditional API calls (like REST).

2️⃣ Asynchronous RPC

• Client does not wait for a response, allowing parallel execution.
• Example: Event-driven microservices.

🔹 RPC vs. REST API

🔹 Popular RPC Frameworks

🔹 Example of RPC Call

Using gRPC (Google RPC) in Python:

import grpc
import example_pb2
import example_pb2_grpc

channel = grpc.insecure_channel('localhost:50051')
stub = example_pb2_grpc.GreeterStub(channel)
response = stub.SayHello(example_pb2.HelloRequest(name='Alice'))
print(response.message)
Code language: JavaScript (javascript)

✅ This sends an RPC request to a server and gets a response.

🎯 When to Use RPC?

✅ When high-speed communication is needed (Microservices, Cloud).
✅ When APIs must support streaming & multiplexing (gRPC).
✅ When services need to communicate in different programming languages.

What is an RPC Framework?

🔹 What is an RPC Framework?

An RPC (Remote Procedure Call) framework is a set of tools, libraries, and protocols that allow applications to execute functions or procedures on a remote server as if they were local functions.

✅ Purpose: Simplifies communication between distributed systems, microservices, and cloud applications.
✅ Example Use Case: A frontend app calling a backend function on a remote server without worrying about networking details.

🔹 How Does an RPC Framework Work?

1️⃣ Client makes an RPC request (calls a function remotely).
2️⃣ RPC framework serializes the request (converts data into a transportable format).
3️⃣ Server receives and processes the request.
4️⃣ RPC framework deserializes the response and returns it to the client.

📌 Example of an RPC Call Flow:

Client  ──> RPC Framework ──> Network ──> Server  
Client  <── RPC Framework <── Network <── Server Response

💡 Think of it like calling a function, but it runs on another server! 🚀

🔹 Popular RPC Frameworks

🔹 Why Use an RPC Framework?

✅ Simplicity → Developers call remote functions like local functions.
✅ High Performance → Many frameworks (like gRPC) use binary serialization for fast data transmission.
✅ Cross-Language Support → Works across different programming languages (e.g., Python client calling a Go server).
✅ Streaming Support → Some frameworks (e.g., gRPC) support bidirectional streaming.

🔹 gRPC Example (Python)

Define an RPC Service (hello.proto):

syntax = "proto3";

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

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}
Code language: JavaScript (javascript)

✅ The RPC framework handles serialization, networking, and responses automatically!

🎯 Final Thoughts

🔥 An RPC framework helps build high-performance distributed systems efficiently! 🔥
✅ Best for: Microservices, Cloud APIs, and High-Speed Communication.
✅ Best choice: gRPC for modern systems, Thrift for cross-language, and JSON-RPC for web apps.

Difference Between RPC and RPC Framework

How RPC Works (Conceptually)?

1️⃣ Client Calls a Function

• A client program calls a function (getUserDetails()) that is actually located on a remote server.

2️⃣ Request Serialization

• The function call’s parameters (data) are converted into a format that can be transmitted over a network (e.g., JSON, Protocol Buffers, XML, Binary).

3️⃣ Network Transmission

• The serialized data is sent over a network (via HTTP, TCP, UDP, WebSockets, etc.).

4️⃣ Server Receives the Request

• The server’s RPC system deserializes the request and calls the actual function on the server.

5️⃣ Function Execution & Response

• The server executes the function (getUserDetails()) and sends the response back to the client.

6️⃣ Client Receives the Response

• The client deserializes the response and continues execution as if the function ran locally.

📌 RPC Conceptual Flow:

pgsqlCopyEditClient ───> (Serialize Data) ───> Network ───> Server  
Server ───> (Execute Function) ───> Return Response ───> Client  

🔹 RPC vs. Normal Function Calls

🔹 Real-World Use Cases of RPC

✅ Microservices Communication → Services talk to each other in cloud-native applications.
✅ Database Requests → Clients call database functions remotely.
✅ Remote System Administration → Commands are executed on remote servers.
✅ Game Servers & Multiplayer Apps → Actions from one player affect other players over a network.

🔹 List of All Popular RPC Frameworks

RPC frameworks simplify remote function execution by handling networking, serialization, and security. Below is a list of widely used RPC frameworks categorized based on their use cases.

1️⃣ Modern High-Performance RPC Frameworks

2️⃣ Web-Based RPC Frameworks

3️⃣ Messaging-Based RPC Frameworks

4️⃣ Enterprise & Legacy RPC Frameworks

5️⃣ Blockchain & Decentralized RPC Frameworks

🔹 Choosing the Right RPC Framework

🎯 Final Thoughts

✅ If you need a high-performance modern RPC framework, use gRPC or Apache Thrift.
✅ For web-based applications, JSON-RPC is a lightweight option.
✅ For low-latency, high-speed messaging, ZeroMQ or Cap’n Proto are great choices.
✅ For distributed systems and big data, Apache Avro is recommended.

🔹 Default RPC Methods in Different Scenarios

Below is a breakdown of what happens by default when you call a remote function in different environments.

Rajesh Kumar

I’m Rajesh Kumar, a DevOps, SRE, DevSecOps, Cloud, and Platform Engineering expert passionate about sharing practical knowledge, real-world experiences, and industry best practices. I have worked at Cotocus and regularly write about technology, travel, investing, health, product reviews, and digital marketing through my various platforms.

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