From: mskuhn@immd4.informatik.uni-erlangen.de (Markus Kuhn)
Subject: Re: DFR for anonymous archives & hypertext
Organization: CSD., University of Erlangen, Germany
Date: Thu, 16 Apr 1992 18:27:49 GMT

Thank you for your very interesting description of some aspects of DFR.

cmf851@huxley.anu.edu.au (Albert Langer) writes:

>The "basic attributes" available on any DFR implementation include the
>following sub-string searchable attributes as well as title and pathname:

>Version-Name, External-Location, User-Reference, 
>User-Reference-To-Other-Objects.

What is the semanitics behind external-location and the references?

>>   - distributed search operations

>Result should be more like "Prospero" than archie - i.e. you browse
>within your own "home" DFR store organized how you want it, and it
>transparently goes and gets information from other DFR stores when
>you actually need it - either for an actual content, or to be able
>to browse the attributes of a collection of documents.

May I compare this mode of operation a little bit with mounting
a file system?

>>   - a well defined unique identifier for each document

>So, if you have a system of mirror or cache sites, it is only necessary
>to coordinate the "base" used by each site for a given sub-tree, and the
>same "relative-path-name" accesses would apply. There are cumulative
>"search-result-lists" that could easily be used for automatic updating between
>archives (including user creation of such mirroring on the fly).

I got the idea between your lines, but I am still confused. Could you please
give a small example?

May a DOR be used to uniquely identify a document world wide (i.e. there
may be sereral copies of THIS document available and all have the same DOR),
and the system will try to get the "nearest location" of a document with this
DOR?

E.g. imagine I have a distributed hypertext system (as implemented on the
Internet with WWW). A link in a text file will show to a document. Is
the DOR the appropriate information that should be stored in the link?
Will it be possible in the ISO HyTime standard (will become final IS this
summer, see comp.text.sgml) to use a DOR as a link to an other remote
(e.g. again HyTime) document?

Together with powerful search methods and perhaps indexes (as planned
for the OSI group communication standard) hypertext will be a very
powerful tool helping you to find the information quickly.

Looking forward to easy browsing facilities through a large universe
of documents ...

Markus

[BTW: if you have never heard of WWW, the WorldWideWeb project, just
get the file /pub/WWWLineMode_v.vv.tar.Z (take the highest v.vv)
from the anonymous ftp site info.cern.ch (128.141.201.74) and install
it on a UNIX machine with Internet access. This is very easy (20 minutes)]

[[The above [...] text is a good example of a hypertext link with DOR.
Unfortunately, it's not very machine readable, so you have to start ftp
manually. ]]

---
Markus Kuhn, Computer Science student -=-=- University of Erlangen, Germany
Internet: mskuhn@immd4.informatik.uni-erlangen.de  |  X.500 entry available
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