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RE: Media Type Sub-Sub-types?

From: Larry Masinter <LMM@acm.org>
Date: Mon, 5 Apr 2010 15:55:15 -0700
To: <xiao@renci.org>, "'Story Henry'" <henry.story@bblfish.net>
Cc: <nathan@webr3.org>, <www-tag@w3.org>
Message-ID: <002301cad513$112bab90$338302b0$@org>
An "Internet Media Type" is more than a definition of syntax --
it's is an indication of intent, by the sender, for how the sender
wishes the receiver to interpret the content being sent.

While it's desirable, alas it is not supported:
The space of "Internet Media Types" does not provide sufficient
granularity for many applications that want to use the accept:
header to control negotiation. 

But the types available do not partition the space of 
syntax and semantics. 

One of the sources of analysis for thinking about file types
and file formats is the archival community.

http://hul.harvard.edu/ois/digpres/guidance.html

In addition, there is the IETF work on "media features":
http://tools.ietf.org/html/rfc2912
http://tools.ietf.org/html/rfc2506
http://tools.ietf.org/html/rfc2938 

which was intended to provide additional information about
the file format other than the Internet Media Type.

I think part of the advice I'd like to include are things
that Internet Media Types (MIME types) *aren't* good for,
even though people have tried or might think it is desirable.

http://en.wikipedia.org/wiki/Internet_media_type


RTP and SIP have extended MIME types in ways that don't
exactly match MIME for email, but so has the web.

Larry


-----Original Message-----
From: Xiaoshu Wang [mailto:xiao@renci.org] 
Sent: Monday, April 05, 2010 2:09 PM
To: Story Henry
Cc: nathan@webr3.org; Larry Masinter; www-tag@w3.org
Subject: Re: Media Type Sub-Sub-types?

On 4/5/10 2:44 PM, Story Henry wrote:
> On 5 Apr 2010, at 01:07, Nathan wrote:
>
>    
>> For instance, if the need for an ****+rdf media type scenario came
>> about, then the specification / media type could determine a fixed
>> serialization, as in only n3 not rdf/xml or other.
>>      
>
> This is really the wrong way to do things. Media types should not determine
> what the content of what you are going to get back is about, only
> what the syntax is.
>    
This is not true. A document should have two types -- one is syntax and 
the other semantic. (Syntax is also deal with semantic as everything 
else in the world but it deals with the structural semantics as opposed 
to domain semantics).

I work in the life science domain. And often there are more than one 
markup languages of the same syntax, e.g., in XML. The same data thus 
can be expressed in more than one way. And since the domain semantics of 
these markup languages are overlapping but subsuming each other, we face 
a dilemma of how to serve them. To give each ML a URI faces the question 
of how to linked them together. Even with the same markup languages, we 
faced the problem how to serve different version of data under the same 
URI. Using content negotiation helps solve these problem. But without a 
document-type definition, it does work as well. Also, giving the type 
definition a URI makes it further linked. I have discussed the issue at 
http://wot.renci.org/tr/doc_uri.

I used to define the document type as an extension to the current type. 
Similar to Jan's proposal of using profile but using a different token. 
However, I find it that I can not use that convention to serve with 
straight-forward Apache's var file. The convention that I used is

mime/type/semantic-type.

Thus, in Jan's case, it would be as follows:

application/http://xmlns.com/foaf/0.1/


> The way the atom people are working on creating a mime type for every
> application is crazy. There are an infinite number of things one can speak about. Should we have an infinite number of mime types? Clearly not.
>
> The better way to do things is to have do it through links. So when you have
>
> :joe foaf:knows :jack .
>
> The the document in which :jack is defined is clearly going to be some form of personal profile document.... At least you should find more info about jack.
>    
Well, I don't think that is good enough. If I am a JavaScript engine, 
what should I get once I got to foaf:knows? I don't read RDF, only JSON. 
Even if I can read JSON, that does not mean that I know how to 
meaningfully processes all JSON's constructs that are out there, right?

Xiaoshu
Received on Monday, 5 April 2010 22:55:59 UTC

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