(:source
   :version             3
   :ip-address          "128.138.243.150"
   :ip-name             "bruno.cs.colorado.edu"
   :tcp-port            8000
   :database-name       "aftp-cs-colorado-edu"
   :cost                0.00
   :cost-unit           :free
   :maintainer          "hardy@cs.colorado.edu"
   :description 
"You can use this WAIS server to search and retrieve files from the
anonymous ftp archive on ftp.cs.colorado.edu [128.138.243.151].  We
used Essence, a resource discovery system based on semantic file
indexing, to build the WAIS index for this server.  As explained below,
Essence currently only allows the retrieval of file summaries through
WAIS.  To retrieve entire files, use anonymous ftp on ftp.cs.colorado.edu.

Essence exploits file semantics to index both textual and binary
files.  By exploiting semantics, Essence extracts keywords that
summarize a file, and generates a compact yet representative index.
Essence understands nested file structures (such as uuencoded,
compressed, ``tar'' files), and recursively unravels such files to
generate summaries for them.  Essence generates indexes that are ten
times smaller than WAIS indexes, but retain the fine-grained
information access that WAIS's full-text indexes provide.

Furthermore, Essence generates WAIS-compatible indexes allowing WAIS
users to make use of Essence's indexing capabilities.  This is one of
the ways that the Networked Resource Discovery Project at the
University of Colorado has extended the conceptual paradigm of the type
of information that WAIS handles.

If you would like to learn more about Essence, you can obtain the
source to the Essence prototype and a paper which appears in the 1993
Winter USENIX Technical Conference, San Diego, CA, January 1993, 
pp. 361-374.  Both the paper and the prototype are available via 
anonymous ftp from ftp.cs.colorado.edu in /pub/cs/distribs/essence.  
Or search for the keyword 'Essence' using this WAIS server to find all 
of the files on ftp.cs.colorado.edu that are related to Essence; you 
will find the files for both the paper and the prototype.

This WAIS server was created in January 1993 by Darren R. Hardy and
Michael F. Schwartz as part of the Networked Resource Discovery
Project.  You may reach them at the Department of Computer Science,
University of Colorado, Boulder, CO  80309-0430, or via email at
hardy@cs.colorado.edu and schwartz@cs.colorado.edu.

Below is some more information about the WAIS interface to Essence.

        Essence exports its indexes through WAIS's search and
        retrieval interface, allowing users to use tools such as
        waissearch and the X Windows-based graphical user interface
        xwais.  In order to generate WAIS-compatible indexes,
        Essence uses WAIS's indexing software to index the Essence
        summary files.  This mechanism generates full-text WAIS
        indexes from the Essence summary files.

        We modified the WAIS indexing mechanism to understand the
        format of the Essence summary files, so that it generates
        meaningful WAIS headlines.  These headlines provide users
        with a short description of a single file, usually a
        filename.  In Essence, headlines represent the filename,
        its file type, and the file's core filename.

        To support additional file types, WAIS must be recompiled
        with new procedures that understand these file types.  With
        Essence, one need only write a new summarizer, add its name
        to a configuration file, and add new heuristics for
        identifying the file type; no recompilation is necessary.
        In this sense, Essence modularizes the typed-file indexing
        extensions that WAIS can use, because it removes the
        keyword extraction process from WAIS and places it instead
        in Essence.  Essence is better suited to incorporating new
        file types, and can be quickly adapted to become a
        comprehensive indexing system.

        The following waissearch output shows an example search of
        an index generated by Essence of the ftp.cs.colorado.edu
        anonymous FTP file system.  It shows an ordered list of the
        ten files that best match the keyword netfind.  Netfind is
        an Internet user directory service.  The headlines have 
        three fields representing the matching file summary: the filename
        (or the last component of the core filename, in some cases),
        the file type, and the core filename.
 
------------------------------------------------------------

csh% waissearch netfind
   1:  Techniques.Wide.Area.ps PostScript 
       /cs/ftp/techreports/schwartz/PostScript/Techniques.Wide.Area.ps.Z 

   2:  PostScript/Techniques.Wide.Area.ps PostScript
       /cs/ftp/techreports/schwartz/PostScript/ALL.PS.tar.Z 

   3:  ServerShell/nsh.c C /cs/ftp/distribs/netfind/netfind3.10.tar.Z 

   4:  README README /cs/ftp/distribs/netfind/README

   5:  README README /cs/ftp/distribs/netfind/netfind3.10.tar.Z

   6:  Doc/netfind.1 ManPage /cs/ftp/distribs/netfind/netfind3.10.tar.Z 

   7:  Proj.Overview.ps PostScript 
       /cs/ftp/techreports/schwartz/PostScript/Proj.Overview.ps.Z 

   8:  RD.Comparison.ps PostScript
       /cs/ftp/techreports/schwartz/PostScript/RD.Comparison.ps.Z 

   9:  PostScript/Proj.Overview.ps PostScript 
       /cs/ftp/techreports/schwartz/PostScript/ALL.PS.tar.Z 

   10: PostScript/RD.Comparison.ps PostScript
       /cs/ftp/techreports/schwartz/PostScript/ALL.PS.tar.Z 
csh%

------------------------------------------------------------

        Consider the effectiveness of the example search shown
        above.  The best match is a PostScript paper that discusses
        a number of techniques for distributed information systems,
        with particular emphasis on techniques demonstrated by
        Netfind; the second match is the same file, but found in
        the compressed tar distribution ALL.PS.tar.Z.  The third
        match is the C source code for the interactive user
        interface to Netfind.  The fourth match is the README file
        found in the Netfind distribution directory; the fifth
        match is the same file, but found in the compressed tar
        distribution netfind.3.10.tar.Z.  The sixth match is the
        UNIX manual page for Netfind.  The remaining matches are
        PostScript papers in which Netfind is discussed.

        In WAIS, a user retrieves files by selecting a matching
        headline.  With Essence, if the headline represents a file
        hidden within a nested file (such as the first headline in the
        example), the summary file is retrieved, instead of retrieving
        the hidden file itself.  If the headline represents a plain
        file (such as the fourth headline in the example), the summary
        file is also retrieved.  This functionality requires allocating
        storage for both the required summary files and the index.
        However, it allows users to browse through remote file systems
        by retrieving and viewing small summary files without having to
        retrieve complete files.  This is useful when trying to decide
        whether to transfer large files across a slow network.  
" 
)
