Web Service Differences Between REST and RPC

As web applications and distributed systems continue to evolve, service-oriented architectures and distributed system designs have become increasingly important. In this field, REST and RPC are two widely used architectural styles. In a previous article, we discussed the comparison between gRPC and REST in terms of speed, efficiency, and flexibility.

Today, we will individually introduce the concepts and characteristics of REST and RPC, and then analyze the differences between REST and RPC from various perspectives. Finally, we will examine the applicable scenarios for REST and RPC and look ahead to their future development.

What are REST and RPC?

REST (Representational State Transfer) is a resource-oriented architectural style that utilizes the HTTP protocol for building web services and APIs. RESTful APIs allow clients to manipulate remote resources through simple HTTP requests, such as GET, POST, PUT, and DELETE. Resources can include text, images, audio, video, and more. RESTful APIs typically use JSON or XML formats to represent data.

RPC (Remote Procedure Call) is a procedure-oriented remote invocation protocol that enables applications to make remote calls over the network, similar to local function calls. RPC facilitates communication between clients and servers by transmitting parameters and returning values. RPC can utilize various transport protocols, such as TCP, UDP, and HTTP.

Differences Between REST and RPC

REST and RPC differ significantly in several aspects, including communication protocols, data transmission, encoding methods, service contracts, and more. Let's analyze the differences between REST and RPC from these perspectives, accompanied by code examples.

Communication Protocol

RESTful APIs use the HTTP protocol as the communication protocol, while RPC can employ multiple transport protocols for communication. In the HTTP protocol, requests and responses are text-based, including request headers, request bodies, response headers, and response bodies. Here's a simple example of a RESTful API implemented in Node.js:

const express = require('express');
const bodyParser = require('body-parser');

const app = express();
const PORT = 3000;

let todos = [
  { id: 1, title: 'Learn Node.js', completed: false },
  { id: 2, title: 'Learn React', completed: false },
  { id: 3, title: 'Learn Redux', completed: false }
];

app.use(bodyParser.json());

// get all tasks
app.get('/todos', (req, res) => {
  res.json(todos);
});

// add a task
app.post('/todos', (req, res) => {
  const todo = req.body;
  todo.id = todos.length + 1;
  todos.push(todo);
  res.json(todo);
});

// modify a task
app.put('/todos/:id', (req, res) => {
  const id = Number(req.params.id);
  const todo = req.body;
  todos = todos.map((item) => {
    if (item.id === id) {
  return { ...item, ...todo };
}
return item;
});
res.json(todo);
});

// delete a task
app.delete('/todos/:id', (req, res) => {
const id = Number(req.params.id);
todos = todos.filter((item) => item.id !== id);
res.json({});
});
app.listen(PORT, () => {
console.log(Server is running at http://localhost:${PORT});
});

You can communicate with multiple transition protocols, such as TCP, UDP, HTTP, ETC. Here is a simple RPC server with Python.

```python
import socket

def square(x):
    return x * x

def handle_request(conn):
    while True:
        data = conn.recv(1024)
        if not data:
            break
        x = int(data)
        result = square(x)
        conn.send(str(result).encode())

def serve():
    s = socket.socket()
    host = socket.gethostname()
    port = 12345
    s.bind((host, port))
    s.listen(5)
    while True:
        conn, addr = s.accept()
        handle_request(conn)
        conn.close()

if __name__ == '__main__':
    serve()

Data Transmission

RESTful APIs use JSON or XML format to represent data, while RPC can use a variety of encoding methods for data transfer. In RESTful APIs, data is usually transferred via HTTP request bodies, which can use JSON or XML format to represent data. The following is a simple RESTful API client implemented using Axios:

import axios from 'axios';

const BASE_URL = 'http://localhost:3000';

// get all tasks
export const getTodos = async () => {
  const res = await axios.get(`${BASE_URL}/todos`);
  return res.data;
};

// add a task
export const addTodo = async (todo) => {
  const res = await axios.post(`${BASE_URL}/todos`, todo);
  return res.data;
};

// modify a task 
export const updateTodo = async (id, todo) => {
  const res = await axios.put(`${BASE_URL}/todos/${id}`, todo);
  return res.data;
};

// delete a task
export const deleteTodo = async (id) => {
  const res = await axios.delete(`${BASE_URL}/todos/${id}`);
  return res.data;
};

You can communicate with multiple encoding methods, such as Protocol Buffers, Thrift, Avro, etc. Here is a simple RPC server with gRPC.

import grpc
import square_pb2
import square_pb2_grpc

def main():
    channel = grpc.insecure_channel('localhost:50051')
    stub = square_pb2_grpc.SquareStub(channel)
    request = square_pb2.SquareRequest(x=10)
    response = stub.Square(request)
    print(response.result)

if __name__ == '__main__':
    main()

Encoding Methods

RESTful APIs use JSON or XML formats for encoding, while RPC can use various encoding methods. In RESTful APIs, data is typically encoded using JSON or XML formats. Here is a simple JSON encoding implemented using JavaScript:

const data = { name: 'Tom', age: 20 };
const json = JSON.stringify(data);
console.log
(json); // {"name":"Tom","age":20}

In RPC, multiple encoding methods can be used, such as Protocol Buffers, Thrift, Avro, etc. Here is a simple implementation of Protocol Buffers encoding using Python:

import square_pb2

def main():    
    request = square_pb2.SquareRequest()
    request.x = 10
    data = request.SerializeToString()
    print(data)

if __name__ == '__main__':
    main()

Service Contract

The service contract of a RESTful API is typically defined through URL, HTTP methods, HTTP headers, and HTTP status codes. Here is a simple service contract of a RESTful API implemented using Node.js:

URL           HTTP Method   Description
/todos         GET          Get all tasks
/todos         POST         Add a task
/todos/:id     PUT          Modify a task
/todos/:id     DELETE       Delete a task

In RPC, the service contract is usually defined using Interface Definition Language (IDL). IDL can define data types, service methods, and exceptions, which can then be used by a compiler to generate client and server code. Here is an example of defining a service contract using Protocol Buffers:

syntax = "proto3";

package example;

message SquareRequest {
  int32 x = 1;
}

message SquareResponse {
  int32 result = 1;
}

service Square {
  rpc Square(SquareRequest) returns (SquareResponse) {}
}

REST and RPC application scenarios

REST and RPC have their own advantages and applicability in different scenarios. Here are common use cases for each:

REST use cases:

RESTful APIs are suitable for building web services and APIs. They use HTTP as the transport protocol and JSON or XML formats to represent data. The design of RESTful APIs should follow the REST architectural style, including resource definition, URL design, the use of HTTP methods, and response status codes.

\1. Web services: REST's statelessness and HTTP-based nature make it a common choice for building web services and APIs. It is suitable for resource-centric applications such as social media platforms, e-commerce websites, news websites, etc.

\2. Large-scale distributed systems: REST's scalability and loose coupling make it suitable for large-scale distributed systems, where functionality can be implemented through multiple independent services communicating via HTTP.

\3. Cross-platform and cross-language integration: REST's usage of standard HTTP protocol and data formats like JSON or XML make it convenient for integration between different platforms and languages, enabling interoperability across systems.

RPC use cases:

RPC is suitable for building distributed systems and microservices. It can use various transport protocols for communication and supports multiple programming languages and frameworks. RPC design follows object-oriented principles, including interface definition, method definition, and parameter and return value definitions.

\1. Microservices architecture: RPC is widely used in building microservices architecture, facilitating communication and collaboration between services through remote method invocation. It can provide higher performance and tighter integration, suitable for real-time communication and low-latency scenarios.

\2. Internal communication in distributed systems: RPC is suitable for building internal communication mechanisms within distributed databases, file systems, or computing clusters for communication between nodes.

\3. Applications requiring specific scenarios: RPC is suitable for applications that require precise control and high customization, such as financial trading systems, game servers, etc.

Currently, many mainstream companies and projects use either REST or RPC, such as:

• REST: Facebook, Twitter, GitHub, Amazon, Microsoft, Google, etc.
• RPC: gRPC, Apache Thrift, Netflix OSS, Finagle, etc.

Future Directions of REST and RPC Development

With the advancement of cloud computing and big data, distributed systems and microservices architecture are becoming increasingly important. REST and RPC are both significant architectural styles for distributed systems, each with its own strengths and limitations. In the future, both REST and RPC will continue to evolve and thrive.

REST will place more emphasis on security and performance. RESTful APIs can use security mechanisms like OAuth, JWT, etc., to ensure the security of user data. Additionally, RESTful APIs can utilize caching mechanisms to improve performance and efficiency. In the future, RESTful APIs may become more intelligent and adaptive, optimizing API performance and efficiency through technologies like machine learning and artificial intelligence.

RPC will focus more on reliability and scalability. RPC can employ techniques like load balancing, fault tolerance mechanisms, and automatic scaling to enhance system reliability and scalability. Furthermore, RPC can become more intelligent and adaptive, optimizing RPC performance and efficiency through techniques like adaptive transport protocols and encoding.

In summary, both REST and RPC are crucial architectural styles for distributed systems, each with its own strengths and limitations. When choosing between REST and RPC, the selection should be based on specific application scenarios and requirements. As technology continues to advance, REST and RPC will continue to evolve and contribute to the development of distributed systems and microservices architecture.