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Re: Last Call: <draft-faltstrom-uri-10.txt> (The Uniform Resource Identifier (URI) DNS Resource Record) to Proposed Standard

2015-01-29 10:33:28
On 29 jan 2015, at 06:33, Mark Nottingham <mnot(_at_)mnot(_dot_)net> wrote:

The RRType is registered and can not be changed.

That said, what can be referred to is a "better" registry for services. IETF 
do not have a registry for services for SRV. If IETF did, then I would have 
referenced that registry. I think it is "stupid" to create a new registry. 
This draft refer to the ENUM Service Registry. For SRV no real registry 
exists, but the DNS-SD people have this: 
<http://www.dns-sd.org/servicetypes.html>

I think most of my concern centres around things appearing in the registry 
without coordination with the community surrounding that service -- such as 
the Web / HTTP case.

I completely understand.

I.e., if the URI RR points to a registry, and that registry contains an entry 
for a service "foo", I expect that applications that implement "foo" should 
use the URI RR in their operation.

When this isn't the case, it's not good for interoperability, potential 
security issues are introduced, and the community of the service often isn't 
involved in the registration.

The draft and registries for prefixes in DNS (specifically SRV, as I explain 
above) has been discussed in the apps area of IETF for years, and no resolution 
of that question have been reached yet. :-(

So, I'm going to ever-so-gently push back on your characterisation of a new 
registry here as "stupid."

Oh, sorry, it was not my intention to express things that strongly.

What I think I think (!) is that as we do not have any clear registry for 
service prefixes in DNS, and SRV has been surviving quite well without, and to 
some degree also many parts of "the web" community, is it important to have 
_any_ specific registry? Can this just evolve?

Is your suggestion to add more examples? I think that is a fair request that 
makes lot of sense.

It'd help, yes. It'd also be good to have the conversation with the Web 
folks, to see where that goes (perhaps they'll want to support it, but if 
they don't, it might be good to take that
example out).

Ok.

And on top of that you have already pointed at the issue with lookups in DNS 
compared to the HTTP transport, where also lots of redirects are common, 
specifically in CDNs, virtual hosting (www.example.com / example.com is a 
trivial example of course) etc.

For now -- note that as we write, the IAB workshop on TCP evolution is 
considering how to move protocols like HTTP to UDP :)

...and some people want to move DNS to TCP and give up UDP :-)

But you also point at a for the IETF sensible issue. When the well known URI 
was discussed, I did present the URI RRType (and SRV, and NAPTR and...) but 
as too often happens "the web community" responded with "we can only look up 
A records". So the use of more efficient mixes of DNS and HTTP to reach the 
for the user best experience was never really discussed. Not there, not 
then, not before and not after. :-(

We've been trying to get discussion going between the HTTP and DNS 
communities, with limited success. Maybe it's time to try again (e.g., in 
Dallas as a Bar BoF)?

Yeah, see the discussions around what DNS features are expected in HTTP/2 and I 
am crying a bit.

Now when we are trying to get a GOOD protocol definition, why can not that 
include good things from BOTH http and DNS worlds(*)?

  paf

(*) I am thinking of including SRV/URI/whatever higher abstraction layer in DNS 
in the protocol spec, and "limit" "happy eyeballs" to repeated HTTP 
transactions over A/AAAA record types. I do not think that discussion have been 
held, as pushback from web to DNS community feels like "oh no, that is too 
hard", which is as I know you and I agree about, the wrong answer.


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