How to set up nodejs middle layer

With the rapid development of the Internet, Web applications are becoming more and more complex and large. Therefore, in order to improve the maintainability and scalability of web applications, many web developers adopt the middle-tier architectural pattern. The Node.js middle tier is a common middle tier implementation because Node.js has efficient I/O operation performance and can easily implement event-driven programming.

This article will introduce how to build a simple middle layer in Node.js and implement some common functions.

1. What is the middle layer

The middle layer refers to the layer between the client and the server. Its main function is to process client requests and send requests to the server. In web applications, the middle layer is often used to integrate different services into one application to better handle complex business logic. In addition, the middle layer can also be used to implement functions such as caching, authentication, and authorization.

2. Node.js middle layer implementation

In Node.js, there are two main ways to implement the middle layer: Socket middle layer based on WebSocket protocol and HTTP middle layer based on HTTP protocol layer. Among them, the HTTP middle layer is the most commonly used method because it is compatible with Web standards and is easy to implement and maintain.

The following is a simple Node.js middle layer example, which implements functions such as request forwarding, request caching, and request logging:

const http = require('http');
const request = require('request');
const url = require('url');

http.createServer((req, res) => {
  // 解析前端请求的url
  const urlObject = url.parse(req.url);
  
  // 配置中间层请求的选项参数
  const options = {
    url: 'http://backend-service' + urlObject.path,
    headers: req.headers
  };
  
  // 处理GET请求的缓存功能
  if (req.method === 'GET') {
    // 检查缓存中是否有数据
    const cacheData = cache.get(options.url);
    if (cacheData) {
      res.writeHead(200, cacheData.headers);
      res.end(cacheData.body);
      console.log('cache hit: ' + options.url);
      return;
    }
  }
  
  // 请求发送到后端服务
  console.log('forwarding request: ' + options.url);
  const proxyRequest = request(options);
  
  // 处理GET请求的缓存功能
  if (req.method === 'GET') {
    // 将响应数据缓存到cache中
    proxyRequest.on('response', (response) => {
      cache.set(options.url, response, response.headers['cache-control']);
    });
  }
  
  // 将请求响应返回给前端
  req.pipe(proxyRequest).pipe(res);
  
  // 请求日志记录
  console.log(req.method + ' ' + req.url + ' ' + res.statusCode);
}).listen(8080);

In the above code, we use Node. The built-in http module in js creates an HTTP server. After the request reaches the server, we first parse the URL requested by the front-end and forward the request to the back-end service (the default here is backend-service) according to the URL address. Before forwarding the request to the back-end service, we also performed some processing on the request:

1. Cache function for processing GET requests: During the validity period, if there is response data for the request in the cache, then Directly return the data in the cache to the front end to avoid repeated requests for back-end services.
2. Record request log: Output the requested method, URL and response status code to the Node.js console.

In addition, the Node.js middle layer can also implement many other functions, such as request authentication, authorization, current limiting, circuit breaker, etc.

3. Summary

The middle layer is a type of Web application architecture pattern. Its main function is to integrate different services into one application in order to better handle complex businesses. logic. In Node.js, we can implement the middle layer through HTTP or WebSocket protocols. The HTTP protocol is compatible with Web standards and is easy to implement and maintain, so it is the most common middle-tier implementation method.

When building the Node.js middle layer, we can use the efficient I/O operation performance and event-driven programming characteristics of Node.js to implement some common functions, such as request forwarding, request caching and request Logging etc. In addition, the Node.js middle layer can also implement many other functions, such as request authentication, authorization, current limiting and fusing, etc., to improve the maintainability and scalability of web applications.

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