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RE: open annotation / media fragments

From: erik mannens <erik.mannens@ugent.be>
Date: Tue, 13 Oct 2009 09:32:05 +0200
To: "'Jack Jansen'" <Jack.Jansen@cwi.nl>, "'Silvia Pfeiffer'" <silviapfeiffer1@gmail.com>
Cc: <public-media-fragment@w3.org>
Message-ID: <004701ca4bd7$438a2820$ca9e7860$@mannens@ugent.be>
Dear all, 

Here's already some feedback/clarification on our feedback ...


Dear all,

Many thanks for having started a discussion about the mail I sent via Erik
Mannens, last week.  Based on your feedback so far, I would like to make
some clarifications regarding the proposal I formulated:

1. The current approaches specified by your Media Fragment work are crucial
for the Open Annotation project I am involved in. We will extensively apply

2. The currently specified Media Fragment approaches can all be regarded as
"by-value" descriptions of segments of resources, i.e. the fragment on the
URI contains all the information required to specify the segment. An example
from your specs is

3.The "by-value" approach of (2) can cover a lot of cases, but when trying
to specify a complex segment of a resource it will most likely not provide
an adequate level of expressivity. Think, for example, of an arbitrary path
drawn on top of an image resource.  In order to cover these kinds of cases,
we think a generic "by-reference" approach would be a flexible solution
providing extensibility. 

4. We think that a by-reference approach aligned with your existing
approaches would consist of a pointer expressed as a fragment on a URI. The
pointer refers to a resource that contains a description of a complex
segment of the resource. For example:
t.xml, whereby:
- http://www.example.com/example.jpg is the image for which a complex
segment is being specified;
- http://www.example.com/segment.svg is a machine-readable document that
describes the segment.

5. The essence of our approach is the fragment/pointer mechanism.
Communities could leverage this generic mechanism by specifying which types
of machine-readable documents should be used to specify segments for which
types of resources (e.g. by media types). Hence, the generic by-reference
approach would allow covering a wide variety of cases including the ones
mentioned I mentioned in my original post (arbitrary segments of an image;
slices/views of dataset, regions in a 3D resource). Indeed, they would most
likely require a different kind of machine-readable document to describe the
segment,  but the pointer mechanism would be shared by all.

6. We do understand that, unlike in your current approaches, the
by-reference approach would not always yield the possibility of generating a
sub-resource that only contains the specified segment. But, it would always
allow the delineation of the "region of interest" in the original resource.
For example, the SVG-expressed path could be overlaid on the image by a
client or server.

7. We also understand that we could define our own fragment approach to
handle these cases, but given the similarity of the problem spaces, we would
very much prefer this to be covered in a W3C spec that focuses on media
fragments already.

I hope this clarifies our request/proposal.

Kind regards

Herbert Van de Sompel

Herbert Van de Sompel
Digital Library Research & Prototyping
Los Alamos National Laboratory, Research Library
tel. +1 505 667 1267

-----Original Message-----
From: Jack Jansen [mailto:Jack.Jansen@cwi.nl] 
Sent: maandag 12 oktober 2009 9:53
To: Silvia Pfeiffer
Cc: erik mannens; public-media-fragment@w3.org
Subject: Re: open annotation / media fragments

On 11 okt 2009, at 13:36, Silvia Pfeiffer wrote:

>> I wonder whether this class of problems fits in the scope of the  
>> Media
>> Fragment work, and if so, whether it is something that you would be  
>> willing
>> to further discuss and maybe even take on board. It goes without  
>> saying that
>> we would be very happy to provide help if that were deemed  
>> appropriate
>> and/or welcome.
> Honestly: I didn't quite understand what technology he wants to
> integrate. Is it reference files that can point to arbitrary segments?
> Is it non-square regions? Is it slices/views of scientific datasets,
> or regions in a 3D resource? I think all of these require different
> solutions. I cannot really see that they are part of the same "class
> of problems" and solvable with the same approach. Or does anyone see a
> way?

I _think_ what he wants is a unified scheme (from a user point of  
view) to specify fragments.

And, actually, I had already started drafting a reply that I think  
this could be worthwhile with some ideas on how to implement this,  
when I realised that it's indeed completely out of scope for MFWG.

While we could define some sort of an extension scheme to our  
fragments this doesn't really buy anyone anything. There's no use  
sending these to servers, so we could only talk about the URL schemes  
anyway, and in the URL scheme space it's really only the four name/ 
value pairs we've defined that we care about.

I think the OP should go about it the other way around: define his own  
Open Annotation Fragment Identifier, and in there state that any MFWG  
fragment is automatically an OAFI fragment identifier. He would then  
only have to define the meaning of his own name/value pairs and the  
interaction between those and ours.
Jack Jansen, <Jack.Jansen@cwi.nl>, http://www.cwi.nl/~jack
If I can't dance I don't want to be part of your revolution -- Emma  
Received on Tuesday, 13 October 2009 07:32:41 UTC

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