HTTP Getting started with HTTP HTTP/0.9

Example

The first version of HTTP that came into existence is 0.9, often referred to as "HTTP As Implemented." A common description of 0.9 is "a subsect of the full HTTP [i.e. 1.0] protocol." However, this greatly fails to illustrate the disparity in capabilities between 0.9 and 1.0.

Neither requests nor responses in 0.9 feature headers. Requests consist of a single CRLF-terminated line of GET, followed by a space, followed by the requested resource URL. Responses are expected to be a single HTML document. The end of said document is marked by dropping the connection server-side. There are no facilities to indicate success or failure of an operation. The only interactive property is the search string which is closely tied to the <isindex> HTML tag.

Usage of HTTP/0.9 is nowadays exceptionally rare. It is occasionally seen on embedded systems as an alternative to tftp.