W3 addresses for WAIS servers
Servers using the WAIS ("Wide Area Information Systems") protocols
from Thinking Machines may be accessed as part of the web using addresses
of the form (see BNF description)
w a i s : / / hostport / database ...
Access (currently) goes through a gateway which stores the "source"
files which contain the descriptions of WAIS servers. This address
corresponds to the address of an index. To this may optionally be
appended either a search string or a document identifier.
Note that changes have been proposed to WAIS document id format, so
this representation of them may have to change with that format. Currently
the WAIS document address necessary for retrieval by a client requires
the following information, which is orginally provided by the server
in the hit list.
- Document format
- This is normally "TEXT" but other formats such as PS,
GIF, exist.
- Document length
- This is needed by the client who must loop to retrie
the whole document in slices.
- Document identifier
- This is an entity consisting of numerically tagged
fields. the binary representation used by WAIS is transformed for
readability into a sequence of fields each consisting of a decimal
tag, an equals sign (=) , the field value, and a semicolon. Within
the field value, hex escaping is used for otherwise illegal characters.
See also: Other W3 address formats, BNF definition.
_________________________________________________________________
Tim BL