USENIX Board Studies UUCP: Compression

[Henry Spencer]

In article <Dec.1.00.15.11.1989.10246 at pilot.njin.net> limonce at pilot.njin.net (Tom Limoncelli) writes:
>1 -- First, don't send messages that have already arrived at the site.
>I know the algorithm used now is great, but it is not near-optimal.
>How about a "I have xxxx" / "Send me yyy" negotiation?  ...

This already exists:  the ihave/sendme protocol.  It's not great.  Apart
from reliability issues, the main problem is that it slows things down
quite a bit.

Most uucp-fed sites don't have multiple feeds, and the answer is always
"no, I haven't seen that yet, please send it".  So the delay and the extra
traffic is pointless.  Ihave/sendme protocols really work *well* only
over real-time connections like the Internet.  (This is what NNTP is
all about.)

>2 -- A new compression scheme.  We all know that the current one is
>quite good, but I have one addition...
>...a string like "<93061 at pyramid.pyramid.com>1:3".  This would mean
>something like "message '<93061 at pyramid.pyramid.com' lines 1 thru 3".
>This is 30 bytes instead of about 300 bytes.  This requires (1) the
>other site has that message already. (2) the user did only trivial
>editing of the old post.

Unfortunately, (1) simply cannot be taken for granted.  They may not
have received it.  They may have dropped it on the floor.  They may
have already expired it (not an insignificant possibility as volume
continues to rise, and you generally don't know what your neighbors'
expiry policies are).  And sensible posters edit included text quite
a bit, usually.  The bulk of the traffic on the net is *not* included
text.

>...Usenet software would reach a hypertext state...

There are people who are interested in doing this.  However, it's *not*
trivial to do.  It's a research area, not something we can immediately
tap for useful results.
-- 
Mars can wait:  we've barely   |     Henry Spencer at U of Toronto Zoology
started exploring the Moon.    | uunet!attcan!utzoo!henry henry at zoo.toronto.edu