protocol(Protocol)

The used protocol. This is, after the optional url:, an identifier separated from the remainder of the URL using :. parse_url/2 assumes the http protocol if no protocol is specified and the URL can be parsed as a valid HTTP url. In addition to the RFC-1738 specified protocols, the file protocol is supported as well.

host(Host)

Host-name or IP-address on which the resource is located. Supported by all network-based protocols.

port(Port)

Integer port-number to access on the \arg{Host}. This only appears if the port is explicitly specified in the URL. Implicit default ports (e.g., 80 for HTTP) do not appear in the part-list.

path(Path)

(File-) path addressed by the URL. This is supported for the ftp, http and file protocols. If no path appears, the library generates the path /.

search(ListOfNameValue)

Search-specification of HTTP URL. This is the part after the ?, normally used to transfer data from HTML forms that use the HTTP GET method. In the URL it consists of a www-form-encoded list of Name=Value pairs. This is mapped to a list of Prolog Name=Value terms with decoded names and values.

fragment(Fragment)

Fragment specification of HTTP URL. This is the part after the # character.

The example below illustrates all of this for an HTTP URL.

?- parse_url('http://www.xyz.org/hello?msg=Hello+World%21#x',
       P).

P = [ protocol(http),
      host('www.xyz.org'),
      fragment(x),
      search([ msg = 'Hello World!'
             ]),
      path('/hello')
    ]

By instantiating the parts-list this predicate can be used to create a URL.