Network Protocols

Specific Schemes

The mapping for some existing standard and experimental protocols is outlined in the BNF syntax definition. Notes on particular protocols follow. The schemes covered are:

   ftp                     File Transfer protocol
   http                    Hypertext Transfer Protocol
   gopher                  The Gopher protocol
   mailto                  Electronic mail address
   news                    USENET news
   nntp                    USENET news using NNTP access
   telnet                  Reference to interactive sessions
   wais                    Wide Area Information Servers
   file                    Host-specific file names
   prospero                Prospero Directory Service

Other schemes may be specified by future specifications.

Common Internet Scheme Syntax

While the syntax for the rest of the URL may vary depending on the particular scheme selected, URL schemes that involve the direct use of an IP-based protocol to a specified host on the Internet use a common syntax for the scheme-specific data:

        //<user>:<password>@<host>:<port>/<url-path>

Some or all of the parts "<user>:<password>@", ":<password>", ":<port>", and "/<url-path>" may be excluded. The scheme specific data start with a double slash "//" to indicate that it complies with the common Internet scheme syntax. The different components obey the following rules:

user
An optional user name. Some schemes (e.g., ftp) allow the specification of a user name.

password
An optional password. If present, it follows the user name separated from it by a colon.

The user name (and password), if present, are followed by a commercial at-sign "@". Within the user and password field, any ":", "@", or "/" must be encoded.