Study on Http protocol

1.      Overall operation

The http process is on the request/response way to communicate.

(1)   Client sends request to server.

(2)   Server responses the request.

(3)   There can be proxy, gateway or tunnel on the links between the client and server.

2.      HTTP Message

(1) HTTP-message   = Request | Response     ; HTTP/1.1 messages

(2)message header :

message-header = field-name ":" [ field-value ]

       field-name     = token

       field-value    = *( field-content | LWS )

       field-content  = <the OCTETs making up the field-value

                        and consisting of either *TEXT or combinations

                        of token, separators, and quoted-string>

(3)       message-body = entity-body

                    | <entity-body encoded as per Transfer-Encoding>

 

(4) The transfer-length of a message is the length of the message-body as it appears in the message; that is, after any transfer-codings have been applied.

 

 

3.      Request

(1)   The request packet format:

Request       = Request-Line              ;                        *(( general-header;| request-header;| entity-header) CRLF)  ;    

 CRLF

 [ message-body ]; 

 

(2)   Format of Request-line:

       Method   Request-URI   Version  CRLF

(3)   Method includes: OPTIONS, PUT, POST, GET, DELETE, HEAD, CONNECT etc.

(4)   Difference between POST and PUT

         PUT is to send data to a specified URI or in another word, to a specified object.

(5)            POST is just to tell that I will send the data, it can be processed as you will.

(6)    Request-URI    = "*" | absoluteURI | abs_path | authority

(7)    The request-header fields allow the client to pass additional information about the request, and about the client itself, to the server. These fields act as request modifiers, with semantics equivalent to the parameters on a programming language method invocation.