Path: utzoo!mnetor!uunet!husc6!think!ames!mailrus!umix!umich!mibte!gamma!ulysses!thumper!faline!bellcore!tness7!ninja!sys1!techsup!cpe!tif
From: tif@cpe.UUCP
Newsgroups: comp.sources.d
Subject: Re: Standard for file transmission
Message-ID: <6800015@cpe>
Date: 4 May 88 19:38:00 GMT
References: <292@cullsj.UUCP>
Lines: 76
Nf-ID: #R:cullsj.UUCP:292:cpe:6800015:000:2937
Nf-From: cpe.UUCP!tif    May  4 14:38:00 1988


Written 10:45 am  May  2, 1988 by bbn.com!rsalz in cpe:comp.sources.d
>If you are (sigh) going to post binaries on Usenet, DO NOT compress
>them first.  Many Usenet sites use compress to pack up their news
>batches.  Compressing a compressed file makes it larger.

<< I don't post often and this about as close to a flame as I've come >>

But what you're compressing is text.  Text can always be compressed
with a significant advantage even if the text is a uuencoded compress
file.  In the end, the uuencode offsets most of the gains of the extra
compress.

If I were implementing a compressing file transfer utility which had
the possibity of transfering *binary* files, I would make sure that
the compress was actually profitable.

Since now adays most "news" transfers are compressed, I'll give in
that *if* "news" could transfer binary files, the compressing should
be left to the news transfer stuff rather than be done by the poster.

Since "news" can't handle binary files (at least nobody assumes
that it can), the file has to be encoded in some way.  I'll use
my kernel as a sample binary input file and uuencode for the
encoding technique.  I've included the results for my /usr/dict/words
file as well since postings sometimes intermix binary and ASCII files.

(I couldn't figure out what order these should be in)

(12 bit compresses only)		Net change of transfer size
transfer	posted			binary		ASCII
-------------------------------------------------------------------
uncompressed	normal			* no change	no change
compressed	normal			* -35%		-46%
uncompressed	uuencoded		+40%		+40%
uncompressed	uuencoded compress	-9%		-25%
compressed	uuencoded		-15%		-23%
compressed	uuencoded compress	-19%		-29%

(if you believe in 16 bit compresses)	Net change of transfer size
transfer	posted			binary		ASCII
-------------------------------------------------------------------
compressed	normal			* -43%		-49%
uncompressed	uuencoded compress	-20%		-28%
compressed	uuencoded		-28%		-30%
compressed	uuencoded compress	-31%		-35%

	* These can't be posted but are provided for reference

CONCLUSIONS:	To transfer binary files using news software the best
		method in all cases is to post a uuencoded compress file.

		When transfering ASCII files, if you compress and uuencode,
		not only are you robbing a 15-20% savings from the sites
		that use compressed transfers, but you should be shot for
		making it unreadable.

For the skeptics, here are the file sizes I used to build the tables:

16 bit compress		12 bit compress
234157			234157			xenix	
133183			152458			xenix.Z	
327860			327860			xenix.u	
167759			198043			xenix.u.Z
186498			213482			xenix.Z.u
161860			190137			xenix.Z.u.Z
194192			194192			words
99725			104093			words.Z
271908			271908			words.u
135065			150047			words.u.Z
139656			145772			words.Z.u
126459			137701			words.Z.u.Z

			Paul Chamberlain
			Computer Product Engineering, Tandy Corp.
			ihnp4!sys1!cpe!tif