标头和正文在http中的响应和请求的顺序是什么？

Question

I was just reading a Wikipedia article about "list of HTTP header fields " an come to this line which says;"the header field are transmitted after the request or response line, which is the first line of a message ". Does it means when writing a program let's say a CGI program we first send the response body and headers should be placed at the bottom of the CGI script. But based on my experience with CGI program in python , we used to write header first and then write some CRLF and after that we write response body.

Can some please help me here to understand correct order of body and headers in http ?

Answer 1

Does it means when writing a program let's say a CGI program we first send the response body and headers should be placed at the bottom of the CGI script.

No this is incorrect.

the header field are transmitted after the request or response line ,

Notice the emphathized "line". The request line is simply something like GET /index.html HTTP/1.1 and is the first line of each request. The headers are transmitted after this, and then after the headers come the body.

If you have access to curl (OS X or Linux terminal), try something like curl -v http://www.google.com . On my machine you see the order clearly:

Request:

> GET / HTTP/1.1
> User-Agent: curl/7.38.0
> Host: www.google.com
> Accept: */*
> 

The body is always empty for a GET request, but a POST you would see the data sent.