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Re: ISSUE-2: What is the mime type of a media fragment? What is its relation with its parent resource?

From: Michael Hausenblas <michael.hausenblas@deri.org>
Date: Wed, 28 Jan 2009 00:12:32 +0000
To: RaphaŽl Troncy <Raphael.Troncy@cwi.nl>
CC: Yves Lafon <ylafon@w3.org>, Media Fragment <public-media-fragment@w3.org>, Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Message-ID: <C5A55370.1506%michael.hausenblas@deri.org>


I know, impolite, but let's start at the end:

> Does that answer to your question?

No ;)

For some background reading I'd suggest [1].

The problem is that with the pure syntax (as of [2]) we can't fully specify
any conformance (UA, or whatever).


In RDFa (where I've been responsible for the TC, now with Manu Sporny
together), we have a processing model that would generally define how to
process an XHMTL+RDFa page in order to produce RDF triple. Now, we can't
define the output for any case (obviously too many combinations possible ;)
In order to define the semantics we use the TC [3]. I'll use the first TC in
the suite as an example:

...<p>This photo was taken by <span class="author" about="photo1.jpg"
property="dc:creator">Mark Birbeck</span>.</p> ...

in our understanding should produce the triple

dc:creator "Mark Birbeck" .

Hence a back and forth between syntax and TC in order to define the
semantics. We reviewed each TC manually and the RDFa TF would then agree,
yes, this is the expected outcome (in sync with the syntax).

Then, after the TC have been completed the implementers were called (yeah,
sure they already did that in parallel, but theoretically sufficient if you
do it later).

In this second phase, the TC were used to determine if and to which degree
the RDFa syntax spec could be implemented (and, alas, also, if you have two
implementations that pass all TC you might be able to assume they are
interoperable). This is an important criteria in the Rec Track [4]:

"The Working Group is NOT REQUIRED to show that a technical report has two
independent and interoperable implementations as part of a request to the
Director to announce a Call for Implementations. However, the Working Group
SHOULD include a report of present and expected implementations as part of
the request."

Though not required I guess it is common and a good practice and fosters

Now, back to the question: How does the above described map to our work?

Take <http://www.example.com/movie.mov#xywh=20,20,40,40> as an example.

How would the TC look? How do we specify the semantics of it?


[1] http://www.w3.org/QA/WG/2005/01/test-faq
[2] http://www.w3.org/2008/WebVideo/Fragments/wiki/Syntax
[3] http://rdfa.digitalbazaar.com/rdfa-test-harness/
[4] http://www.w3.org/2005/10/Process-20051014/tr.html#cfi

Dr. Michael Hausenblas
DERI - Digital Enterprise Research Institute
National University of Ireland, Lower Dangan,
Galway, Ireland, Europe
Tel. +353 91 495730

> From: RaphaŽl Troncy <Raphael.Troncy@cwi.nl>
> Organization: CWI
> Date: Wed, 28 Jan 2009 00:35:04 +0100
> To: Michael Hausenblas <michael.hausenblas@deri.org>
> Cc: Yves Lafon <ylafon@w3.org>, Media Fragment <public-media-fragment@w3.org>,
> Silvia Pfeiffer <silviapfeiffer1@gmail.com>
> Subject: Re: ISSUE-2: What is the mime type of a media fragment? What is its
> relation with its parent resource?
> Dear Michael,
>> I'll restate it and would like to ask you to explain me how we gonna handle
>> this - in case I understand it I offer a bounty (not sure if that has
>> already been assigned, so ...), that is, to take care of the Test Cases:
> [Being not Yves]
> What is exactly your question? What would be the implementations of the
> spec and the test cases that come with for the CR exit?
> What we have discussed so far:
>    - implementation of a smart UA, that can transform the fragment
> requested into some new http headers and do either the 2-ways or the
> 4-ways handshake ... ideally in collaboration with the browser vendors.
>    - implementation of a server, that can handle media fragment request,
> slide the media file on demand, and serve it to the client
> Yves has his own server (jigsaw)
> Jack though he could do something with Ambulant, the SMIL player.
> Test cases will ensure that communication between UA and server will
> follow what is specified in the spec (re: 2-ways / 4-ways handshake in
> case of http implementation, etc.)
> Does that answer to your question?
> Best regards.
>    RaphaŽl
> -- 
> RaphaŽl Troncy
> CWI (Centre for Mathematics and Computer Science),
> Science Park 123, 1098 XG Amsterdam, The Netherlands
> e-mail: raphael.troncy@cwi.nl & raphael.troncy@gmail.com
> Tel: +31 (0)20 - 592 4093
> Fax: +31 (0)20 - 592 4312
> Web: http://www.cwi.nl/~troncy/
Received on Wednesday, 28 January 2009 00:13:16 UTC

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