Re: Possible addition to Squid?

Some comments on compressing web connections:

(1) Ages ago I wrote a TCP proxy that compresses connections. You can get
it from ftp://ftp.ox.ac.uk/pub/users/loader/znet-0.4.tar.gz
It compresses using the gzip algorithm (the zlib library), and recycles TCP
connections to avoid the three-way handshake overhead.

It's pretty basic, but quite effective, over a 9600 baud PPP link, anyway.
I don't intend to maintain it because I just got ethernet, although it
could be improved in various ways.

(2) As someone pointed out, many large objects are not (easily)
compressible. Using a general purpose compression on small objects is
probably not worthwhile. It's not uncommon that gzip for instance, doesn't
manage to reduce the size of a file that contains only a few hundred bytes.

On the other hand, HTTP transactions contain a quite predictable header.
An efficient binary encoding of headers (and possibly HTML tags) could well
be both quicker and more effective than a general purpose compression
algorithm, at least for small objects.

(3) There's little reason at all to put compression into squid, at least
for TCP connections. If your link is slow enough to make the overhead of
compression worth-while, then you're not going to notice the additional
overhead of the data passing through an external compression program.

Ralph.
Received on Wed Dec 11 1996 - 01:48:17 MST