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Understand the basic history and knowledge of HTTP

2022-04-29 12:16:48InfoQ

1990 Years ago

Before the 1990s , The Internet has not been invented yet , At that time, the Internet basically sent e-mail (Email1965 The invention of ) And other forms are simple and practical

1990 Years later, the world

  • Tim Berners-Lee( Hereinafter referred to as Sir Lee )  stay  1989  -  1992  Year , Invented  WWW(World Wide Web)
  • It mainly includes three concepts

  • URI, Commonly known as the website

  • HTTP, A protocol for transferring content between two computers

  • HTML, Hypertext , Mainly used to do page Jump

  • URL  The function of is to let you visit a page ,HTTP  The function of is to let you download this page ,HTML  The function of is to let you understand this page

  • Perfect match, not tired to work
  • In addition to inventing these concepts , also :

  • Invented the first server

  • Invented the first browser

  • Wrote the first web page

  • He won the most prestigious award in the field of computer science —— Turing Award

  • The father of the World Wide Web Tim Berners-Lee Turing award : Bonus 100 Thousands of dollars ( Click to view the award information )

URI(Uniform Resource Identifier)

Is a string used to identify the name of an Internet resource URI  It is divided into  URL  and  URN, We usually use  URL  As web address
  • URN( Uniform resource code )

  • ISBN: 9787115275790  It's just one.  URN, adopt  URN  You can be sure of one 「 Unique 」 resources ,ISBN: 9787115275790  The corresponding resource is 《JavaScript  Advanced programming ( The third edition )》 This book . You're going to introduce any library 、 The bookstore , They all know it's this book .
  • URL( Uniform resource locator )

  • adopt  URL  You can be sure of one 【 Unique 】 Address ( website )

null
First level domain name com Two level domain name baidu Three level domain name www

null
www.baidu.com

DNS

  • Enter the domain name
  • Output IP

Server + Client + HTTP

The browser is responsible for initiating the request, and the server is in  80  The port receiving request server is responsible for returning the content ( Respond to ) The browser is responsible for downloading the response content HTTP  The role of is to guide the browser (Clinet) And the server (Server) How to communicate
Request example
1.url -s -v -H "Frank: xxx" -- "https://www.baidu.com" The requested content is
GET / HTTP/1.1

Host: www.baidu.com

User-Agent: curl/7.54.0

Accept: */*

Frank: xxx
  •  
curl -X POST -s -v -H "Frank: xxx" -- "https://www.baidu.com" The requested content is
POST / HTTP/1.1

Host: www.baidu.com

User-Agent: curl/7.54.0

Accept: */*

Frank: xxx
Format of request
1  Verb   route   agreement / edition

2 Key1: value1

2 Key2: value2

2 Key3: value3

2 Content-Type: application/x-www-form-urlencoded

2 Host: www.baidu.com

2 User-Agent: curl/7.54.0

3

4  Data to upload
The request consists of at most four parts , There are at least three parts .( That is to say, the fourth part can be empty ) The third part is always a carriage return (\n) Verb has  GET POST PUT PATCH DELETE HEAD OPTIONS The path here includes 「 Query parameters 」, But does not include 「 Anchor point 」( The anchor point is viewed by the browser , The server doesn't see ) If you don't write the path , So the default path is  / The first  2  In section  Content-Type  Marked the  4  Part of the format

use  Chrome  Send the request

open  Network Enter the web address in the address bar  Network  Click on , see  request, Click on 「view source」 Click on 「view source」 Click on 「view source」 Click on 「view source」 Finally ordered ? You can see the first three parts of the request. If there is a fourth part of the request , So in  FormData  or  Payload  You can see it in it

Respond to

Format of response
1  agreement / Version number   Status code   State interpretation

2 Key1: value1

2 Key2: value2

2 Content-Length: 17931

2 Content-Type: text/html

3

4  What to download
The status code should be memorized , It's what the server says to the browser
1xx  Not commonly used
2xx  It means success
3xx  Go away
4xx  It means you are wrong
5xx  Say ok , I was wrong
Status code query
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use  Chrome  View the response

open  Network Enter the URL and select the first response to view  Response Headers, Click on 「view source」, Click on 「view source」, Click on 「view source」 You will see the first two parts of the response  Response  perhaps  Preview, You'll see the response number  4  part
 

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