Re: IANA Media Types

The W3C tends to prefer things that are URIs to keep it simple, 
decentralized, and extensible. I believe the W3C has asked the powers to be 
with respect to IANA take some action to commit to a URI based allocation, 
but it hasn't happened... (For example for extensibility purposes, one 
*should* be able to plug in a non-IANA blessed type, and if it's a URL, it 
has the capacity to be self-describing!) 

On Monday 29 October 2001 18:52, Dournaee, Blake wrote:
> Does anyone know why the media type tree is hosted at www.isi.edu (or if
> this isn't "the" tree, why isn't it at www.iana.org, or something
> similar).

If there is a iana.org rooted URI I would use it. (Don, you mentioned there 
is one?)

> I am just wondering about the history of this. Further, these
> media type designations are the same ones referred to in the DSig spec as
> used in the "MimeType" attribute for the <Object> element. The values
> suggested here are the bare media types names without the fully qualified
> URI shown in the XML Encryption specification.

Yes, in xmldsig we ended up with some Types (as URIs), an Encoding and a 
MIMEType attribute. Kind of awkward, but there were as many attributes as 
there were uses and syntaxes for expressing them.

> This seems odd, is there a compelling reason to have these be different
> between the specifications? With anticipated use of both of these
> technologies together, this just seems weird.

In xmldsig we had three sorts of attributes used for various purposes, in 
xenc we have a single Type attribute which is of type URI. The required 
&xenc;Element and &xenc;Content identifiers have a specific meaning and are 
URIs. We could specify EncryptedData such that it must have a Type (URI) 
*or* MIMEType (string) attribute to be consistent with xmldsig. But it also 
seems silly to perpetuate special syntax because we don't have normative 
URIs for MIMEtypes. (We shouldn't have to invent syntax, people should 
create URI mappings.)

What are you proposing?

-- 

* I will be in France from 3-9 November for the W3C AC Meeting.

Joseph Reagle Jr.                 http://www.w3.org/People/Reagle/
W3C Policy Analyst                mailto:reagle@w3.org
IETF/W3C XML-Signature Co-Chair   http://www.w3.org/Signature/
W3C XML Encryption Chair          http://www.w3.org/Encryption/2001/

Received on Wednesday, 31 October 2001 18:42:43 UTC