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RE: Request feedback on fragment identifiers

From: Larry Masinter <LMM@acm.org>
Date: Wed, 07 Jul 2004 23:26:09 -0700
To: "'Myriam Amielh'" <myriam.amielh@cisra.canon.com.au>, uri@w3.org
Message-id: <0I0I003P9SJL3F@mailsj-v1.corp.adobe.com>


> We believe this approach is in line with some discussions we 
> read on W3C  uri forum:
> http://lists.w3.org/Archives/Public/uri/2004Mar/0030.html

Well:  I don't think it is "in line with" that discussion; that
discussion was about fragments that aren't associated with
"retrieval".

> For that, MPEG-21 could possibly define a fragment identifier for MPEG 
> MIME types such as video/mpeg, audio/mpeg, and so forth. Then MPEG could 
> also propose a Best Current Practise for other MIME-types which do not 
> have an addressing scheme yet: The BCP could suggest the use of a 
> generic fragment identifier scheme (at least, in MPEG-21) for any 
> content type as long as there is no other authoritative addressing 
> scheme. The BCP could also point to existing schemes, as for instance 
> for PDF or XML resources.

I'm not sure how the PDF fragment identifier syntax or the
XML fragment identifier syntax have much to do with
MPEG-21 fragment identifiers.... For application/pdf, there's
one MIME type with one syntax. For XML resources, there
are two MIME types (application/xml, text/xml), and then
a recommendation for what future MIME types might do.

I don't like the idea of having a sort-of-recommendation where
multiple interpretations might apply.

And the XML recommendation isn't necessarily a good precedent;
certainly there have been concerns about deployment for XPath,
and how extensibility will work. I don't think it's sucessfully
deployed.


Without reviewing the MPEG-21 proposed scheme, I don't know
whether to be concerned about verbosity, compatibility with
fragment syntax, or compatibility with other addressing mechanisms
(e.g., SMIL).

> We didn't see anything in the RFCs that may exclude the use of a second 
> fragment interpretation scheme other than an authoritative one that is 
> registered with a particular MIME-type. However, this is an assertion we 
> would like to cross-check with URI experts.

Not a very good line of reasoning ("nothing explicitly forbids this").

How about you working through some of the compatibility scenarios.

I get a pointer that says "Hey, look at this cool guy in this
video!" and you send me a link with a wizzy new fragment identifier.

I click on it, and, behold! I start watching the beginning of
a boring video, because MY resolver doesn't know that you wanted
me to seek to 30-minutes into the thing.

So is this really a good idea?

Larry
Received on Thursday, 8 July 2004 02:41:23 GMT

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