dns media type registration tree

[Mark Baker]

On Sat, Feb 21, 2004 at 02:44:12PM -0500, Keith Moore wrote:
> Let me play Devil's advocate here.

Good stuff Keith, thanks.

> I'm not sure why people assume that just because they are familiar with 
> how to allocate names in a particular name space, that that name space 
> should then be adapted to every purpose that comes to mind.  There is 
> value in having semantics associated with a name space - a value which 
> is diluted by using that name space for a wide variety of purposes.  
> DNS is too overloaded as it is.

Agreed.  The dns tree doesn't remove the need for the IETF tree, nor the
need for review.  IMO, it just does two very useful things; 

- it's a better form of x/vnd/prs tree, especially when combined with my
proposed URI extension

- it enables new authorities to establish their own review policies over
their part of the media tree namespace

> Beyond that, DNS is not well-suited for media types.  DNS assignments 
> are ephemeral.  They are subject to change as their assignees (e.g. the 
> organizations whose names they reflect) merge, split, go bankrupt, fail 
> to renew their registrations, or sell off trademarks.  They are subject 
> to reassignment for arbitrary reasons. We discovered long ego that URIs 
> based on DNS names are not suitable for long-term (archival) use 
> precisely because those names change; that's why URNs and DOIs were 
> invented.  And the utility of URNs has been nearly destroyed by misuse 
> and overloading of that name space.

Gotta disagree there.

There is *far* too much depending upon the DNS->authority mapping to
have it ripped out from under us.  If something eventually replaces DNS
(while still being centrally administered), there will be *enormous*
and IMO, unescapable pressure to have that system be an extension of
DNS so that existing DNS name->authority mappings persist.

P.S. Dan Connolly and I talked about this;

http://www.ietf.org/internet-drafts/draft-connolly-w3c-accessible-registries-00.txt

(... which we should really do something with)

> It must be questioned whether it is beneficial to the public to define 
> new media types on a whim anyway.  The failure to pay proper attention 
> to the design of media types, the failure to do security analysis of 
> media types, and the failure to respect those analyses even when they 
> are done is the reason why email- and web-borne viruses and worms cost 
> billions of dollars to consumers.

Agreed.  See my first response above.

I expect that I disagree with MarkN on this too; I don't think that the
use of XML necessarily requires a multitude of media types (and I'm not
talking about using "application/xml" for everything).  Personally, my
money's on description frameworks like RDF to moderate the need for new
media types.

So while I agree with you that a myriad of media types is bad, I don't
believe that the DNS tree either encourages this (any more than do
existing extensibility processes and mechanisms), nor do I believe that
the tree is only useful in that case.

> If there really is a compelling need (meaning that it serves the 
> greater good) to define new media types at a whim, a much better set of 
> names already exists, one which was more-or-less designed for that 
> purpose.  It's called OIDs.  They are easy to obtain.  They are 
> recursively extensible just like DNS names (actually moreso).  It is 
> relatively well-established that once assigned, the meanings of OIDs do 
> not change.  They don't contain human-readable content that invites 
> disputes over ownership.

They're also not derefenceable.  I think that's a huge loss.  See the
draft mentioned above for more on that subject.

> The argument for DNS media types reminds me of countless other 
> arguments for why protocol X should be used for everything (or at 
> least, every instance of some large class of problem).   In the past X 
> has taken on values such as SOAP, XML, HTTP, SNMP, LDAP, URLs, SSL, 
> ASN.1, RPC, and even TELNET.  Most of those arguments look pretty naive 
> now, but people took them seriously when they were in fashion.  Now 
> it's essentially being argued that since DNS is a widely-deployed 
> namespace and query protocol, that it should be used for yet one more 
> thing that could be looked up.

AFAIK, it's the only universally deployed means of mapping strings to
authorities on the Internet.  I'd also prefer a better solution, but I'm
not aware of any.

> p.s. gratuitous analogy to a famous quote:
> 
> Abraham Maslow is supposed to have said "It is tempting if the only 
> tool you have is a hammer, to treat everything as if it were a nail."
> 
> I like Mike O'Dell's version better, which I'll parphrase since I 
> didn't manage to write it down at the time:
> 
> "If you need to drive a nail, the fact that you have your forehead with 
> you doesn't make it a good tool for the job."

8-)

Mark.
-- 
Mark Baker.   Ottawa, Ontario, CANADA.        http://www.markbaker.ca