Re: Protocol Benchmarking (with Accept examples - long)

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Date: Thu, 3 Feb 1994 09:04:37 +0000 (GMT)
From: "Jon P. Knight" <J.P.Knight@lut.ac.uk>
Subject: Re: Protocol Benchmarking (with Accept examples - long)
To: Lou Montulli <montulli@stat1.cc.ukans.edu>
Cc: Alexsander Totic <atotic@ncsa.uiuc.edu>, altis@ibeam.jf.intel.com,
        koblas@netcom.com, mcrae@ora.com, www-talk@www0.cern.ch
In-reply-to: <9402030037.AA23076@stat1.cc.ukans.edu>
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On Wed, 2 Feb 1994, Lou Montulli wrote:
> 
> If the host sent back the type immediately after the client sends
> the get, the client could check it's list of accepts to see if
> it's an acceptable type, for instance "image/jpeg".  
> If the type is acceptable, the client responds, "OK
> send me the data", otherwise the client says "I don't understand
> image/jpeg" but I do understand "image/gif and image/x-xbm".
> If the server can deliver those types then he sends the data,
> if not then the server may attempt a different sub-group, for
> instance "application/x-mac-draw".  In each case the client
> would only send the accept header of the specified sub-group,
> thereby saving the broadcast of a very large group of accepts.
> 

Correct me if I'm wrong but currently we send Accepts in a single outward
call and get some form of result (either the document or an error)
returned from the server.  With your scheme we send a request, receive a
list of possible types, send back a request for types the client can
handle and then get the reponse from the server.  Therefore we've gone
from one round trip delay to two.  Thus to save transmitting a few bytes
we take an increased latency hit.  Right?  When some of the network links
have RTDs in the thousands of ms from where I'm sitting and yet we have a
nice fat pipe to the Internet, I think we'd rather waste a few bytes on
small documents.  Latency is Your Enemy(tm) in WAN based distributed systems.

Just IMHO.

Jon

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Jon Knight, Research Student in High Performance Networking and Distributed
Systems in the Department of _Computer_Studies_ at Loughborough University.
* Its not how big your share is, its how much you share that's important. *