DNS-based discovery in "HTTP-based Resource Descriptor Discovery"

First I would like to say that I think the draft is in terrific shape, and
compliment Eran for the effort that he showed in putting this together.

In the rest of this email, I am offering my viewpoint on the DNS discovery
issue.

-On the need to make DNS discovery authoritative for site-meta-based
discovery on other URI schemes:

--In practice, I think this is a finer-grained decision that should be left
to applications, while the current form binds this obligation to the scheme,
which is somewhere on the application/transport boundary. A more realistic
standpoint would be to have the standard say that clients performing
discovery on a URI scheme other than HTTP MAY perform DNS discovery and MAY
fail if the DNS record is not available. It could also indicate that
application-level standards that adopt this standard by reference MAY elect
to make this step mandatory (MUST) or recommended (SHOULD) or not
recommended (SHOULD NOT), according to their specific needs.

--Venturing a guess, I expect that HTTP-based schemes such as OpenID/OAuth
will likely spouse the view that DNS discovery is not required for
authoritativeness and will instead infer authority and trust through other
means (e.g., X.509 digital certificates and signatures).


-On the need for a well-known location:
--'/site-meta' or equivalent is unavoidable for HTTP-based discovery, in
particular because the only proposed alternative (DNS records lookup) is not
typically available within popular HTTP API frameworks and this situation is
unlikely to change.

-- 
--Breno

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