gWAIS LINK FORMAT

This document describes Prospero links to files accessible through
WAIS; we have not yet determined a format for WAIS directory & index
lookups.  This format works for both external WAIS links and native
WAIS links (that is, links to WAIS files stored on a server running
Prospero).

The WAIS record locator string has a port # and hostname encoded into
it.  We treat the record locator as an impenetrable object that we
just give to the WAIS server at a particular wais server (WAIS servers
are uniquely identified by a hostname port # pair); Prospero itself
doesn't worry about extracting this information from the WAIS record
locator string.  The person or computer program creating a link to a
WAIS object is responsible for obtaining the WAIS port # and hostname.

The HOSTNAME on the VLINK is the hostname of the prospero server which
stores information about that file.  If the server is running on a
non-standard port, this hostname will be followed by a port number in
parentheses.

The HSONAME on the VLINK for a file which is usually accessed through
WAIS begins with the sequence WAIS/OBJECT/ and then finishes with the
WAIS record locator string.

Not all files which can be retrieved via the WAIS access method will
have an HSONAME on the VLINK in this format.  This is because the
server may send a WAIS access method even for a file that is primarily
accessed through NFS, Anonymous FTP, or some other access method.  In
this case, the ACCESS-METHOD attribute for the file will usually have
the six-token format (described below).

The ACCESS-METHOD attribute for WAIS files consists of 5 [sometimes 6] tokens: 

	WAIS INTERNET-D <hostname> ASCII <hsoname> 
                [optional record locator string]

WAIS, INTERNET-D, and ASCII are literals.

The <hostname> token in the ACCESS-METHOD attribute is the name of the
host whose WAIS server must be contacted to retrieve the object (same
as the hostname encoded into the record locator).  If the WAIS server
is running on the default WAIS port (210), this <hostname> token may be the
normal Internet hostname or it may be followed by the port # in
parentheses.  The <hostname> token must always include the port # in
parentheses if the WAIS server is running on a non-default port.

If a sixth token is present in the WAIS access-method attribute, then
this is the WAIS record locator string which will be sent to the WAIS
server to retrieve the object.  If the sixth token is not present,
then the <hsoname> token of the ACCESS-METHOD attribute must begin with
the sequence WAIS/OBJECT/ and then finish off with the WAIS record
locator string.  The WAIS/OBJECT/ prefix will be stripped off and the
resulting string will be sent to the WAIS server.

The most common case for the WAIS access method is on a link whose
target is FILE (not EXTERNAL) to an object which can be retrieved from
a wais server running on the default WAIS port on the same host as the
PROSPERO server which indexes it, and with the PROSPERO server running
on the default PROSPERO port.  In this case, the HOST and HOSNAME
tokens in the ACCESS-METHOD attribute are the same and those for the
link.  Therefore, using the defaults that apply to all access methods,
the ACCESS-METHOD attribute can be sent across the network as:

	WAIS '' '' '' ''


In the case of an EXTERNAL link to a WAIS object, the HOST and HSONAME
tokens in the vlink are customarially (although this is not strictly
enforced) the same as those for the access method, and the access
method is sent across the network using the defaulting mechanism.