Relevant protocols

The WorldWideWeb system can pick up information from many information sources, using existing protocols. Among these are file and news transfer protocols.

File Transfer

The file transfer protocol currently most used for accessing fairly stable public information over a wide area is "Anonymous FTP". This means the use of the internet File Transfer Protocol without authentication. As the WWW project currently operates for the sake of public information, anonymous FTP is quite appropriate, and WWW can pick up any information provided by anonymous FTP. FTP is defined in RFC 959 which includes material from many previous RFCs. (See also: file address syntax ). Directories are browsed as hypertext. The browser will notice references to files which are in fact accessible as locally mounted (or on DECnet on VMS systems) and use direct access instead.

See also the prospero project and the shift project, for more powerful file access systems.

Network News

The "Network News Transfer Protocol" (NNTP) is defined in RFC 977 by Kantor and Lampsley. This allows transient news information in the USENET news format to be exchanged over the internet. The format of news articles is defined in RFC 850, Standard for Interchange of USENET Messages by Mark Horton. This in turn refers to the standard RFC 822 which defines the format of internet mail messages. News articles make good examples of hypertext, as articles contain references to other articles and news groups. News groups appear like directories, but more informative.

Search and Retrieve

The WWW project defines its own protocol for information transfer, called HTTP, for HyperText Transfer Protocol. HTTP is a very simple internet protocol, similar in implementation to FTP and NNTP. The HTTP client sends a document identifier with or without search words, and the server responds with hypertext or plain text. Extensions are foreseen to allow for more elaborate queries and format negotiation. The protocol runs over TCP, using one connection per document request. The browser acts as a pipeline, so that as data arrives from the server, it is presented to the reader on the fly.

Whilst the HTTP protocol provides a simple keyword search function, a famous search-and-retrieve protocol is Z39.50, and the version of it used by the WAIS project. (See also the WAIS-WWW gateway).

Gopher

The Gopher distributed information system uses a lightweight protocol very similar to HTTP. Therefore, it is now included in every WWW client, so that the Gopher world can be browsed as part of the Web. Gopher menus are easily mapped onto hypertext links. Chances are that future versions of the Gopher and HTTP protocols will converge.