Subject: Re: On attribute-based queries

From: Stuart Cheshire <[email-masked]>
Date: Tue, 6 Aug 2002 19:53:13 -0700

>I work in a field (entertainment technology) where networks
>with several thousand devices came over the horizon
>a while ago and are now knocking on the door.

Really?

Several thousand devices?

Can you back this up with a real example?

I can imagine owning ten or twenty hi-fi components, but not several 
thousand.

I use X10 light switches in my house, but I don't have more than twenty 
or thirty of those.

The cheapest object I think I own is a pencil, but even for something 
that cheap I can't see any reason to own several thousand pencils. I have 
a hard time thinking of any object of which I own several thousand. If I 
do need to own several thousand network devices, that seems like a strong 
argument to make them as cheap and simple as possible.

Stuart Cheshire <[email-masked]>
 * Wizard Without Portfolio, Apple Computer
 * Chairman, IETF ZEROCONF
 * www.stuartcheshire.org

---

From: Stuart Cheshire <[email-masked]>
Date: Tue, 6 Aug 2002 20:36:31 -0700

>You're again bringing this back to the human aspect of "choosing"
>things.  For software agents to search and select services attribute
>-based searching is a necessity.

I never said that attributes weren't important.

What I questioned is whether you want to ship some generic query 
description over the network and have every device interpret the query 
itself, or whether you want get all the information from the devices, and 
then perform your evaluation locally to determine which one (or ones) 
meet your needs.

Those who are old enough will remember the battle between 
ISDN-to-the-desktop and Ethernet.

The ISDN proponents said that the network should be very carefully 
managed, and should never lose a single byte of data. Of course that made 
ISDN switching hardware very slow and expensive compared to an Ethernet 
hub.

The Ethernet vendors said, "Forget call setup. Forget reservations. 
Forget virtual circuits. Just make the hardware so cheap and fast that no 
one cares."

The market spoke. People would rather have fast and cheap. People would 
rather have an uncertain share of 10Mb/s (or 100Mb/s, or Gb/s) than a 
guaranteed 100% of 64kb/s (that's 0.06Mb/s, for anyone who's counting).

I take the same approach here -- I'd rather focus my efforts on making 
the network fast and cheap, and fill it with cheap simple devices, than 
focus my efforts on making complicated devices that have to execute 
generic queries locally in order to preserve the precious bandwidth of my 
slow network.

To state it even more plainly: If a device vendor selling a $50 device 
has a limited budget to spend on either a faster network interface, or on 
a faster processor to execute a more complicated protocol, I'd rather 
have a simple device with a 10Mb/s interface, instead of a more powerful 
device with only a 1Mb/s interface.