How to write nodejs middle layer

With the popularity of front-end and back-end separation, front-end frameworks and technologies are changing with each passing day. How to build a high-performance front-end architecture has become the focus of everyone's attention. One of the key links is how to build an efficient and stable middle layer. This article will introduce how to use Node.js to build the middle layer.

1. What is the middle layer

The middle layer is an independent server layer located between the front end and the back end. It can be used to handle data interaction and processing between the front-end and the back-end, reducing the pressure on the back-end server, while improving the user's response speed and user experience.

2. Why choose Node.js as the middle layer

Node.js is a lightweight and efficient JavaScript runtime environment. It is characterized by event-driven, non-blocking, and asynchronous IO. Less processing and resource usage. These characteristics make Node.js the first choice for the middle layer.

In Node.js, concurrent requests can be processed through the event loop mechanism to achieve high concurrency and high throughput. At the same time, Node.js can handle almost any type of data, and JavaScript can be used for project description and development, reducing learning costs and development costs.

3. How to use Node.js to build the middle layer

1. Install Node.js

First install Node.js and npm (Node.js since With the package management tool), you can download the latest version of the Node.js installation package from the official website (https://nodejs.org/en/) and install it according to the prompts. After the installation is complete, run the following command to verify whether Node.js is installed successfully:

node -v

If the installation is successful, the system will display the version number of Node.js.

2. Installation framework

Use Node.js to develop the middle layer, which can be built using other frameworks such as Express or Koa. This article uses Express as an example to introduce.

Install Express using the following command in the terminal:

npm install express

3. Implementing the middle layer

In order to enable the front end to access the back-end service, you can Write a proxy in , forward the front-end request to the back-end service, and return the response from the back-end service to the front-end.

In order to simplify the sample code, the following business scenario is implemented: when the front end requests http://localhost:3000/api/getUserInfo, the middle layer proxy requests http://localhost:4000/api/getUserInfo and will get The response data is returned to the front end.

Write the following code in the index.js file:

const express = require('express');
const http = require('http');
const app = express();

// 指定后端服务器地址及端口号
const backendHost = 'localhost';
const backendPort = 4000;

// 转发请求
app.get('/api/*', (req, res) => {
  // 构造后端服务地址并发出请求
  const options = {
    hostname: backendHost,
    port: backendPort,
    path: req.originalUrl.replace(/^/api/, ''),
    method: req.method,
    headers: req.headers
  };
  const proxyReq = http.request(options, (proxyRes) => {
    // 响应数据返回给前端
    res.status(proxyRes.statusCode);
    res.set(proxyRes.headers);
    proxyRes.pipe(res);
  });
  req.pipe(proxyReq);
});

app.listen(3000, () => {
  console.log('中间层服务器启动成功，端口号：3000');
});

Run the node index.js command to start the middle-tier service, which will listen to port 3000. At the same time, you need to start the back-end server so that it listens to port 4000 to complete the construction of the entire system. After completing these operations, you can access the http://localhost:3000/api/getUserInfo interface through the browser to check whether the correct results can be obtained normally.

4. Summary

Using Node.js to build the middle layer can effectively reduce the pressure on the back-end server while improving user response speed and user experience. This article introduces the basic principles and construction methods of the Node.js middle layer, and provides a specific code implementation example. I hope it will be helpful to everyone.

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