Subject: RFC 2782 questions

From: Stuart Cheshire <[email-masked]>
Date: Sat, 13 May 2000 18:09:52 -0700

Greetings all.

I'm new to the namedroppers list, though some of you may know me through the
ZEROCONF work.

I've been reading RFC 2782, and a few things are not clear to me. I have
several questions, but I will restrict myself to one question per email, or
things will get very confusing. The first is here; the remainder will follow
in separate messages.

> In general, it is expected that SRV records will be used by clients
> for applications where the relevant protocol specification indicates
> that clients should use the SRV record. Such specification MUST
> define the symbolic name to be used in the Service field of the SRV
> record as described below. It also MUST include security
> considerations. Service SRV records SHOULD NOT be used in the absence
> of such specification.

This seems to imply that I SHOULD NOT write a new web browser that uses an
SRV lookup for _http._tcp.example.com to locate a web server, because HTTP
does not specify the use of SRV records. Is that the intention of this text?
If so, why?

Stuart Cheshire <[email-masked]>

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From: Greg Hudson <[email-masked]>
Date: Sat, 13 May 2000 21:48:34 -0400

> This seems to imply that I SHOULD NOT write a new web browser that
> uses an SRV lookup for _http._tcp.example.com to locate a web
> server, because HTTP does not specify the use of SRV records. Is
> that the intention of this text?  If so, why?

That is precisely the intention of the text (and was the subject of a
little disagreement).  The rationale is that blindly implementing SRV
for existing protocols could cause problems; for example, in the
absence of negative caching, your new web browser could significantly
increase the amount of DNS traffic on the Internet.  By encouraging
people not to implement in absence of some kind of specification
process, the area directors in particular hoped to get people to think
about possible problems earlier rather than later.

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From: Patrik Fältström <[email-masked]>
Date: Sun, 14 May 2000 16:58:48 +0200

>does not specify the use of SRV records. Is that the intention of this text?

That is correct.

Someone have to write the text, even if it is short, on how/where the 
SRV resolution is to be done when you take an HTTP URI and resolve 
it. Think especially about relative URI, and the discussions about 
how to find the base...it is not so simple as one might think.

Also, in the registration of port numbers, I find the following:

>http             80/tcp    World Wide Web HTTP
>http             80/udp    World Wide Web HTTP
>www              80/tcp    World Wide Web HTTP
>www              80/udp    World Wide Web HTTP
>www-http         80/tcp    World Wide Web HTTP
>www-http         80/udp    World Wide Web HTTP

Which one of the words to the left is to be used?

It might be a simple task to write the text, but it has to be done.

    Patrik

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From: Andrew Brown <[email-masked]>
Date: Sun, 14 May 2000 14:31:53 -0400

>Which one of the words to the left is to be used?

imho, http is the protocol or service name (and should be used in the
srv records), www is the function, and www-http is just plain wrong.

-- 
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