Write at the beginning

• Recently Devops and Micro Front End have written almost the same, I started reviewing the knowledge of the back end, I wanted to write this article before, and finally fell to the ground
• If you want to join the front-end communication group, you can contact me at the end to join

Official Start

• Mac|Linux recommended for computer environments
• Install redis and start redis

`redis-server` 

• After successful startup, the following will occur:

• redis default port 6379

Start Writing Node.js Code

• Download redis this library

yarn add redis --save

• Use Node.js Connect redis

const redis = require('redis');

const client = redis.createClient(6379, '127.0.0.1'); 

• Since it's a message queue, you need to have a producer, a consumer

❝

The ubiquitous use of message queues here, like redis, is an out-of-process service, which requires a single port to start the service

❞

What is a message queue?

• Message Queuing is a container that stores messages during their transmission.
• Messages are sent to the queue.Message Queuing is a container that stores messages during their transmission.The Message Queue Manager acts as an intermediary when relaying messages from its source to its destination.The primary purpose of a queue is to provide routing and guarantee the delivery of messages; if the recipient is not available when sending a message, the message queue retains the message until it can be successfully delivered.
• That is, producers, consumers, publishing subscription model implementation

Message Queue Usage Scenario

• Business decoupling
• Asynchronous processing improves performance

• Current Limiting and Peak Cutting (Reducing costs, it is not possible to have servers at peak flow)

Start Implementation

• Producer

`const redis = require('redis');

const client = redis.createClient(6379, '127.0.0.1');

client.on('error', function (err) {
  console.log('err' + err);
});

client.on('ready', function () {
  client.publish('testFirst', 'hi! first!');
  client.publish('testSecond', 'hi! second!');
  client.publish('message', 'hi! message!');
});` 

• Producers publish specific channel s with parameters
• Consumers subscribe to specific channel s, consume, and get data

`const client = require('redis').createClient(6379, '127.0.0.1');

client.on('error', function (err) {
  console.log('err' + err);
});

client.subscribe('testSecond');
client.subscribe('message');
client.on('subscribe', function (channel, count) {
  console.log('subscribe channel:' + channel + ', count:' + count);
});
client.on('message', function (channel, message) {
  console.log('message channel:' + channel + ', msg:' + message);
});
client.on('unsubscribe', function (channel, count) {
  console.log('unsubscribe channel:' + channel + ', count:' + count);
});` 

• Result:

• I subscribed to both the testsecoud and message channels and triggered the subscribe event twice, as expected

Simulate scenarios where producers continually provide production

• Add timer

`const redis = require('redis');

const client = redis.createClient(6379, '127.0.0.1');

client.on('error', function (err) {
  console.log('err' + err);
});

client.on('ready', function () {
  setInterval(() => {
    client.publish('testSecond', 'hi! second!');
    client.publish('message', 'hi! message!');
  },1000);
});` 

• The consumer keeps printing, triggering the message event

❝

In this way, we implemented a simple message queue using redis publishing subscription mode

❞

Achieve flow peak clipping and current limiting

• At present, our production is 1S message, but I want to control 2S consumption once, is that OK?
• We control the frequency of consumption without first changing the frequency of production

`const client = require('redis').createClient(6379, '127.0.0.1');
const ArrayList = [];
client.on('error', function (err) {
  console.log('err' + err);
});
client.subscribe('testSecond');
client.subscribe('message');
client.on('subscribe', function (channel, count) {
  console.log('subscribe channel:' + channel + ', count:' + count);
});
client.on('message', function (channel, message) {
  ArrayList.push({ channel, message });
});
client.on('unsubscribe', function (channel, count) {
  console.log('channel:' + channel + ', count:' + count);
});

setInterval(()=>{
    console.log(ArrayList,'ArrayList')
},2000)` 

• Read queue data every 2S

• What is the difference between the simulation and the reality?

  • The simulation is in a process port and belongs to an in-process cache
  • The truth is that you can confirm consumption by replying to ACK, exclusive to a port process, and belong to an out-of-process cache

A simple message queue via redis is done

• Source address:https://github.com/JinJieTan/MQ