1. Single sign-on

1.1 What is Single Sign-on

Single sign-on (SSO) : Multiple login Prerequisites: Single sign-on (SSO) is used in a distributed system

1.2 the Demo

Visit to the zoo:

  • If you go directly to the zoo, you will be stopped directly, and if you don’t, you will go to the ticket office to buy a ticket
    • Login = buy tickets
  • I’m going to buy a ticket [hold a ticket, get in]
    • Token = tickets
  • We can visit with a ticket

2. The shopping cart

2.1 Definition of shopping cart

  • The relationship between the shopping cart and the user
    • A user must correspond to a shopping cart (no matter how many items a user buys, they are stored in their own shopping cart)
    • Single sign-on must precede the shopping cart
  • What are the operations related to shopping carts
    • Add shopping cart
      • The user is not logged in
        • Where do I add it? Where do I save data without logging in
          • Redis — Jingdong
          • Cookie — your own development can be used
          • If cookies are disabled, they can be stored in LocalStorege
      • User Login Status
        • Redis cache (fast read and write)
          • Hash: hset store (key, field, value)
            • Key : user : userID cart
            • Hset(Key , skuID , value)
        • It is stored in the database (Oracle, mysql) to ensure data security
    • Display shopping cart
      • Unlogged status display
        • Get the data display directly from the cookie
      • Login Status Display
        • Once the user is logged in: the shopping cart data must be displayed in the database (Redis) + Cookie
          • There are three records in the Cookie
          • There are five in Redis
          • There should have been eight

3. Message queues

3.1 background

How is high concurrency handled in distributed systems

  • In a high-concurrency environment, requests that are sent by the user cannot be processed synchronously, resulting in request blocking
    • Too many connections errors are triggered when a large number of Insert,update and other requests are sent to the MySQL database at the same time. The solution is asynchronous communication using message queues
  • asynchronous

  • parallel

  • Line up

  • Usage Scenarios:

  • Disadvantages of message queues:
    • Message uncertainty: delay queue, polling technology to solve the problem