Update README.md

README.md

@@ -10,7 +10,57 @@ It has been designed mainly for educational purposes for C++ developers that can
 
 It can be compiled for both Windows and Linux operating systems (and maybe others).
 
+# HTTP Protocol
+HTTP (Hypertext Transfer Protocol, defined in RFC 2616) is the application protocol used primarily for the delivery of hypertext content on the web. 
+
+The HTTP is transaction-oriented paradigm based, in particular, on the request / response model: the client issues a request to a server that replies with a response. 
+TCP sessions used for the transfer of this exchange, are generally established and terminated for each transaction. 
+This behavior makes it easy to manage hyperlinks which by their nature allow you to mix content belonging to different sources.
+The request / response model can be made more complex in the case in which a non-transparent proxy exists.
+A generic HTTP request message is composed of three parts: 
+the request method (GET, HEAD, POST, etc ...) followed by a URI and the protocol version, 
+a section called header which contains additional information on the method, in the form of attributes (header fields), and finally, if present, 
+the body of the message. 
+A response consists of a status-line containing a three-digit code that provides the result of the response itself. 
+For example, a status line with "HTTP/1.1 200 OK" indicates that the request was successful. 
+Header and (optionally) body follow the status line.
+The body is a generic octet stream, even if there is a characterization that allows the receiver to properly classify it. 
+The header that precedes the body is a sequence of ASCII text lines, each terminated by a couple of the characters CR (0xA) and LF (0xD). 
+
+To summarize a generic HTTP request has the following format:
+
+< method > < URI > < version > < CRLF >
+< header_field _1 >: < value1 > < CRLF >
+< header_field _2 >: < value2 > < CRLF >
+...
+< header_field _N >: < valueN >< CRLF >< CRLF >
+< body ... >
+
+Similarly, a generic response is formatted as follows:
+
+< version > < status code > < status message > < CRLF >
+< header_field _1 >: < value1 >< CRLF >
+< header_field _2 >: < value2 >< CRLF >
+...
+< header_field _N >: < valueN >< CRLF >< CRLF>
+< body ... >
+
+Note that the last line of the header is identified by a double < CRLF > sequence. 
+In practice, the header does not have a predetermined size, but its end and the beginning of the body of the message are identified by this sequence.
+The body can either have a predetermined size (a header attribute called Content-Length is specially used), or it can be terminated when the TCP connection is closed.
+To classify and treat the data transferred in an appropriate manner, a header attribute named Content-Type is used.
+
+There is an encoding of the types of data sent, described in RFC 1521, which provides a classification of the type of content transferred. 
+This classification is called Multimedia Internet Mail Extensions (MIME) because it was originally designed for e-mail messages, and subsequently used for the content of other protocols including HTTP. 
+
+The MIME classification is made by a type, a subtype and optionally a parameter. For example, plain text is normally classified by specifying the attribute 
+"Content-Type: text/plain; charset=us-ascii"
+
+A good example for understanding HTTP is TinyHttpServer is a small web server implemented using C++11.
+
 ![HTTP Server](https://sites.google.com/site/eantcal/archive/tinyhttpserver/tinyhttp.png)
+
+# Tiny HTTP Server Pseudo-code
 ![HTTP Server](https://sites.google.com/site/eantcal/archive/tinyhttpserver/tinyhttp2.png)
 ![HTTP Server](https://sites.google.com/site/eantcal/archive/tinyhttpserver/tinyhttp3.png)