Request = Simple-Request | Full-Request
Simple-Request = "GET" SP Request-URI CRLF
Full-Request = Request-Line ; Section 5.1
*( General-Header ; Section 4.3
| Request-Header ; Section 5.2
| Entity-Header ) ; Section 7.1
CRLF
[ Entity-Body ] ; Section 7.2
如果HTTP/1.0服务器收到简单请求它必须回应一个HTTP/0.9格式的简单回应
HTTP/1.0的客户端有能力接收完整回应但不能产生简单请求