Subject: Re: Application software needs to be "zeroconf-aware"?

From: Keith Moore <[email-masked]>
Date: Wed, 08 Jan 2003 19:00:41 -0500

On Wed, 08 Jan 2003 12:41:18 -0800
Alf Watt <[email-masked]> wrote:

> 
> When communicating an address to a far away host applications SHOULD check
> to make sure it's a public address before sending. 

the application has no way of knowing whether or not the host receiving
the referral is "far away" (or more precisely, within the same addressing
realm).

> Second, due to the dynamic nature of both DHCP and LL self-assigned
> addresses, applications SHOULD perform late binding of network names to
> addresses and not exchange addresses at all. 

that's a gross overgeneralization.  it works well for some applications,
not for others.  DNS names are slow, they are sometimes ambiguous
(multiple names per host or multiple hosts sharing a single name)
and DNS lookup is far less reliable than IP routing.

it never ceases to amaze me that so many people think they understand the 
needs of the entire Internet well enough to make broad statements about
how everyone SHOULD write applications.

-- 
--
Keith Moore                              http://www.cs.utk.edu/~moore/
27 February 1933                                     11 September 2001

---

From: "John C. Welch" <[email-masked]>
Date: Wed, 08 Jan 2003 23:14:49 -0800

> the referral is "far away" (or more precisely, within the same addressing

It can check *very* quickly to see if an address is a LL address or not.

> and DNS lookup is far less reliable than IP routing.

But, DNS is ubiquitous, and far easier for the Hu-mans, so why not use it.
Besides, multiple names per host is not bad, not uncommon, and works fine.
Multiple hosts per name is the same way.

> how everyone SHOULD write applications.

It never ceases to amaze me throughout history how a small number of
determined factionalists have been able to grind progress to a halt for
amazingly long amount of time to promulgate pet religious wars. This of
course explains every problem with Unix.

john

-- 
John C. Welch
Consultant III
Administrative Computing
(617) 253 - 1368 work
(508) 579 - 7380 cell
bynkii2          AIM

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From: Keith Moore <[email-masked]>
Date: Thu, 9 Jan 2003 08:08:45 -0500

On Wed, 08 Jan 2003 23:14:49 -0800

> It can check *very* quickly to see if an address is a LL address or not.

the problem with this strategy is that you cannot do referrals between local
hosts via a third party that isn't on the local link.  e.g. you can't have
a netsolve agent on a remote link mediating between a client and a server that
happen to be on the same link and using LL addresses.

> But, DNS is ubiquitous

no it's not.

> , and far easier for the Hu-mans, so why not use it.

because you want your app to work quickly and reliably.

> Multiple hosts per name is the same way.

it means that just because a DNS name is associated with a host, does not
mean that you can use the DNS name to reliably reach that host.  you 
might end up reaching a different host than the one which has the 
process you need to talk to.

> amazingly long amount of time to promulgate pet religious wars. 

breaking the IP architecture is not progress.  

Keith

---

From: "John C. Welch" <[email-masked]>
Date: Thu, 09 Jan 2003 12:57:22 -0800

> no it's not.

I bet I can find more DNS use than people not using it. He with the most
toys wins.

> because you want your app to work quickly and reliably.

So far so good...this seems to be how the internet progressed anyway. I
imagine all the NCP people were pretty pissed that TCP/IP broke a lot of
stuff...would you rather have stayed with NCP to avoid any possibility of
harm

> process you need to talk to.

That's called load balancing. It's a good thing. There are ways of course to
avoid errors in this area. If you have a proper DNS setup, then the load
balancing service knows what is running on what machine. This of course is a
meaningless argument, which has nothing to do with anything zeroconf -
related.

> breaking the IP architecture is not progress.

Neither is keeping Networking solely in the hands of the high priests of the
orthodoxy, just so they can feel superior.

john

-- 
John C. Welch
Consultant III
Administrative Computing
(617) 253 - 1368 work
(508) 579 - 7380 cell
bynkii2          AIM