1、应用层协议,默认使用80/TCP;

2、RFC文档如下:下载地址为:https://www.rfc-editor.org/

HTTP/1.1

"Message Syntax and Routing" [RFC7230]
"Semantics and Content" [RFC7231]
"Conditional Requests" [RFC7232]
"Range Requests" [RFC7233]
"Caching" [RFC7234]
"Authentication" [RFC7235]

HTTP/2

RFC 7540 and RFC 7541

HTTPS

RFC 2818 - HTTP Over TLS

第一部分 ------ "Message Syntax and Routing" [RFC7230]

如以下例子:获取www.example.com主机上的hello.txt文件
The following example illustrates a typical message exchange for a GET request (Section 4.3.1 of [RFC7231]) on the URI "http://www.example.com/hello.txt":

Client request:客户端请求资源

GET /hello.txt HTTP/1.1
User-Agent: curl/7.16.3 libcurl/7.16.3 OpenSSL/0.9.7l zlib/1.2.3
Host: www.example.com
Accept-Language: en, mi

Server response: 头部后空一行代表头部结束

HTTP/1.1 200 OK
Date: Mon, 27 Jul 2009 12:28:53 GMT
Server: Apache
Last-Modified: Wed, 22 Jul 2009 19:15:56 GMT
ETag: "34aa387-d-1568eb00"
Accept-Ranges: bytes
Content-Length: 51
Vary: Accept-Encoding
Content-Type: text/plain

Hello World! My payload includes a trailing CRLF.