Introduction to the HTTP protocol

HTTP protocol

1. Four characteristics

HTTP协议
    1.四大特性
        1.基于TCP/IP作用于应用层之上的协议
        2.基于请求响应
        3.无状态
            cookie
            session
            token
        4.无连接
            keep-alive

2. The request response data format

        请求首行(请求方式 协议版本)
        请求头(一堆k:v键值对)  就类似于开路先锋 携带了一些服务端可以提前知道的信息
        (/r/n)(如果请求头里没有内容 那就是 /r/n/r/n)
        请求体(发送post请求 携带的数据都会放在请求体中)

3. Response Status Code

The following are common HTTP status codes:

• 200-- request was successful
• 301-- resources (web pages, etc.) is permanently transferred to another URL
• 404 - resources (web pages, etc.) requested does not exist
• 500 - Internal Server Error

HTTP status code classification

classification	Category Description
1**	Information, the server receives the request, the requester needs to continue operation
2**	Successful operation has been successfully received and processed
3**	Redirection, further action is required to complete the request
4**	Client error, the request contains a syntax error or could not fulfill the request
5**	Server Error The server error has occurred during the processing of the request

HTTP protocol Introduction

HTTP protocol messaging format requirements

Each HTTP requests and responses follow the same format, an HTTP Header and Body comprising two portions, wherein Body is optional. Header HTTP response has a Content-Typeshow content format of the response. As text/htmlexpressed HTML page.

HTTP GET request format:

HTTP response format: