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Re: my token about the "3 or more layer" structure for the ontology

From: Felix Sasaki <fsasaki@w3.org>
Date: Mon, 24 Nov 2008 22:44:07 +0900
Message-ID: <492AAFA7.2010007@w3.org>
To: Pierre-Antoine Champin <pchampin@liris.cnrs.fr>
CC: public-media-annotation@w3.org

Pierre-Antoine Champin さんは書きました:
> Hi Felix, thank you for your feedback.
> First, the term "data structure" was a bad choice. I should have written
> "conceptual model", which describes better what I am interested in. I
> think once we agree on a conceptual model, we can chose the best syntax
> to represent it -- if we want to...
> As a matter of fact, I took for granted that we would have to define our
> own format. But once again, the most important thing is the conceptual
> model.

I'm sorry, I have to disagree again. Take again a statement like 
"Mapping for getDate" from
"exif:DateTimeDigitized (based on [MWG Guidelines Image]). This is taken 
only into account if both xmp:createDate and exif:DateTimeOriginal are 
I think this fulfils our task without a conceptual model: to provide 
interoperability between heterogenous metadata formats for video.

> To be clear about my idea of a "conceptual model" or "ontology"... It
> does not necessarily implies that we describe it formally. You advocate
> a "prose" description, and it is indeed a possibility, as long as it is
> precise enough.

Is the approach at
precise enough for you? Please have esp. a look at the terminology section
which interlinks the different bits.

> However, that does not rule out, IMHO, the discussion about structure --
> and I still think structure is important for interoperability problems.
> I take an example:
> ID3 [1] has apparently a flat structure: it is a list of properties with
> text value. However, take the descriptions of the following properties:
>>   TALB
>>    The 'Album/Movie/Show title' frame is intended for the title of the
>>    recording (or source of sound) from which the audio in the file is
>>    taken.
>>   TOAL
>>    The 'Original album/movie/show title' frame is intended for the title
>>    of the original recording (or source of sound), if for example the
>>    music in the file should be a cover of a previously released song.
> There is an awful lot of structure hidden in those flat properties!
> A sound file is *taken from* a *recording*, which has a *title* and can
> be an *album*, a *movie*, a *show* (and the list is probably not
> intended to be exhaustive). But it can have been *previously released*
> in another *recording*.
> So mapping those properties to, say, Dublin Core properties, not only
> requires to find an equivalence between the notion title, but also
> *taken from* (dc:source ?), *previously released* (??), etc...

Good example. My opinion is exaclty that mapping these properties to 
Dublin Core *does not* require finding these equivalences. From our charter:
Success criteria: "Abilitity to convert core metadata information from 
one metadata standard to an other". This does not talk about 
roundtripping, so information loss  is OK.
Out of scope: "Full coverage of all metadata elements in EXIF, IPTC, 
XMP, MPEG-7, and similar broad vocabularies, is out of scope".
I interpret this as "it's OK to loose the structure of ID3 tags is lost 
in the mapping to ID3.".


>   pa
> [1] http://www.id3.org/id3v2.4.0-frames
> Felix Sasaki a écrit :
>> Hello Pierre-Antoine,
>> Pierre-Antoine Champin さんは書きました:
>>> Felix,
>>> although I participated in putting the debate in terms of "XML vs. RDF",
>>> my concern was not about a precise syntax or foramt, and I agree with
>>> you that it should not be.
>> Just for clarification: "agree that it should not be" means "we do not
>> need to define a syntax" or "we should not discuss XML vs. RDF, but need
>> to decide on a syntax"? If the latter, which syntax do you propose?
>>> However in my view the question is more fundamental. Let me reword it.
>>> Designing an ontology involves, IMHO, a trade-off between faithfully
>>> representing the domain of interest, and projecting it in a practical
>>> data structure.
>> Maybe here we already have different opinions: I think we can design an
>> ontology without a practical data structure. The current API / ontology
>> proposal does just that: defining a list of terms *as prose*. The data
>> structure related parts are only in the API, and in the prose mapping
>> descriptions.
>>> Failthful in our context means:
>>> - able to cover a large part of legacy metadata
>>>   - able to satisfy most of the requirements of our use cases
>>> Practical in our context, means that the ontology should be:
>>> - easy to use by media publisher
>>> - easy to implement in browsers
>>> A very easy to use and implement data structure is a list of
>>> (attribute,value) pairs -- the so-called "flat" structure.
>>> By the way, even easier is a list of simple tags -- which can be tweaked
>>> into (attribute,value) pairs anyway, as pointed out by your previous
>>> mail about flickr.
>>> However, I think that this is too much of a simplification:
>>> - it does not satisfy come requirements (like the multi-level or
>>> collection) -- though we might decide that those ones are too complex
>>> - my intuition is that more structure would make "impedence mismatch"
>>> between legacy vocabularies easier to point out and solve
>> I agree that this simplification does not cover many use cases like
>> "multi-level  or collection". But I also think for this version (1.0 of
>> the ontology / API) we should concentrate on the simple approach which
>> is important for all use cases and application scenarios. If that founds
>> adoption, we can shoot for 2.0 and a more complex approach.
>> Btw., of course we have not described all application scenarios, use
>> cases and requirements yet. Nevertheless I think that the requirement to
>> get information across heterogenous formats is central to our WG.
>> I don't think that more or less structure is related to the quality of
>> mapping between different vocabularies. For this mapping, detailed
>> knowledge brought in by the WG parcitipants about these vocabularies is
>> mostly important. If the mapping then is represented in prose, or as
>> more or less structured XML or RDF, is not important IMO. However, I do
>> think that a detailed prose description is important for the API, and it
>> can also help understanding a structured representation, if we decide to
>> do that.
>> Felix
>>>   pa
>>> Felix Sasaki a écrit :
>>>> Ruben Tous (UPC) さんは書きました:
>>>>> Hi Pierre-Antoine, Silvia, all,
>>>>> I think that normalisation/denormalisation is related to the more
>>>>> general discussion about structured*/flat annotations (handling
>>>>> events, agents, etc. as separated structures) . The multi-level
>>>>> description discussion is probably a sub-topic within that general
>>>>> one, and refers only (as I've understood till now) to splitting
>>>>> (normalising) the main structure (the one describing the digital
>>>>> object) into several entities but only regarding different abstraction
>>>>> levels (e.g. document and instance).
>>>>> So, probably we should decide first about the structured*/flat
>>>>> question. If we choose "flat", then we could maybe discard also the
>>>>> multi-level description.
>>>>> Probably, there's a latent high-level question behind this discussion:
>>>>> will the ontology model the way annotations are interchanged, or will
>>>>> it model their underlying semantic grounding?
>>>>> Best regards,
>>>>> Ruben
>>>>> *When talking about structured annotations I'm not just referring to
>>>>> hierarchycal ones (XML), I refer to annotations with ObjectProperties
>>>>> (inlined or linked within the same annotation) (e.g. RDF).
>>>> Reading this discussion and the "features" wiki page, the "data model
>>>> rows", I have the impression that there is some tension between using
>>>> XML and RDF. I can understand that tension, but I think we should not
>>>> spend time on discussing it in this group. Nevertheless, it lets me more
>>>> and more think that we should not be format specific in our ontology,
>>>> but use just a prose description as the normative outcome, that is in
>>>> the "Ontology 1.0" Recommendation. If people want to write non-normative
>>>> RDF- and XML-formats, they are free to do so. I think we should focus on
>>>> formulating the terminology in the prose in a way that that makes a
>>>> formalization in whatever format straightforward.
>>>> Felix
>>>>> ----- Original Message ----- From: "Silvia Pfeiffer"
>>>>> <silviapfeiffer1@gmail.com>
>>>>> To: "Ruben Tous (UPC)" <rtous@ac.upc.edu>
>>>>> Cc: <public-media-annotation@w3.org>
>>>>> Sent: Wednesday, November 19, 2008 10:10 PM
>>>>> Subject: Re: my token about the "3 or more layer" structure for the
>>>>> ontology
>>>>> Hi Ruben,
>>>>> It is always a matter of use cases.
>>>>> When we talk about management of collections, there will be overlap
>>>>> between the annotations of different files, which can be handled more
>>>>> efficiently (in a database sense: normalise your schema).
>>>>> However, if you receive an individual media resource, you want all of
>>>>> its annotations to be available with the media resource, i.e. you want
>>>>> an "intelligent" media object that can tell you things about itself.
>>>>> I don't see these things as separate. Let's take a real-world example.
>>>>> Let's assume I have a Web server with thousands of videos. They fall
>>>>> into categories and within categories into event, where each video
>>>>> within an event has the same metadata about the event. On the server,
>>>>> I would store the metadata in a database. I would do normalisation of
>>>>> the data and just store the data for each event once, but have a
>>>>> relationship table for video-event-relationships. Now, a Web Browser
>>>>> requests one of the videos for playback (or a search engine comes
>>>>> along and asks about the metadata for a video). Of course, I go ahead
>>>>> and extract all related metadata about that video from the database
>>>>> and send it with the video (or in the case of the search engine:
>>>>> without the video). I further have two ways of sending the metadata: I
>>>>> can send it in a text file (which is probably all the search engine
>>>>> needs), or I can send it multiplexed into the video file, e.g. as a
>>>>> metadata header (e.g. MP3 has ID3 for this, Ogg has vorbiscomment,
>>>>> other file formats have different metadata headers).
>>>>> I don't think we need to overly concern ourselves with whether we
>>>>> normalise our data structure. This is an "implementation" issue. We
>>>>> should understand the general way in which metadata is being handled
>>>>> as in the example above and not create schemas that won't work in this
>>>>> and other scenarios. But we should focus on identifying which
>>>>> information is important to keep about a video or audio file.
>>>>> Cheers,
>>>>> Silvia.
>>>>> On Thu, Nov 20, 2008 at 12:01 AM, Ruben Tous (UPC) <rtous@ac.upc.edu>
>>>>> wrote:
>>>>>> Dear Véronique, Silvia, all,
>>>>>> I agree with both of you in that the need of multiple description
>>>>>> levels is
>>>>>> only related to a small subset of use cases, basically to those
>>>>>> related to
>>>>>> the management of groups of resources (e.g. digital asset management
>>>>>> systems, user media collections, etc.). Instead, we are (I guess)
>>>>>> focused in
>>>>>> embedded annotations in individual resources.
>>>>>> However, I think that there are solutions which cover both cases, the
>>>>>> simple
>>>>>> and the complex one. For instance, we could embed the following
>>>>>> annotation
>>>>>> within an MPEG video:
>>>>>> <mawg:Video rdf:ID=http://example.org/video/01">
>>>>>> <mawg:title>astronaut loses tool bag during spacewalk </mawg:title>
>>>>>> <mawg:creator>John Smith</mawg:creator>
>>>>>> </mawg:Video>
>>>>>> <mawg:Resource rdf:ID="http://example.org/resource/01">
>>>>>> <mawg:format>FLV</mawg:format>
>>>>>> <mawg:filesize>21342342</mawg:filesize>
>>>>>> <mawg:duration>PT1004199059S</mawg:duration>
>>>>>> </ mawg:videoID rdf:resource="http://example.org/video/01">
>>>>>> </mawg:Resource>
>>>>>> It is structured and it offers 2 abstraction levels, but it can be
>>>>>> serialized like a plain record. When appearing in isolated resources,
>>>>>> the
>>>>>> high-level annotation ("Video" in this case) would be repeated. When
>>>>>> appearing within a collection's annotation the "Video" annotation
>>>>>> would
>>>>>> appear just once.
>>>>>> It is not so different than in XMP. Take to the following XMP
>>>>>> example...
>>>>>> http://www.w3.org/2008/WebVideo/Annotations/wiki/images/8/8a/Xmp_example.xml
>>>>>> Best regards,
>>>>>> Ruben
>>>>>> ----- Original Message ----- From: <vmalaise@few.vu.nl>
>>>>>> To: <public-media-annotation@w3.org>
>>>>>> Sent: Wednesday, November 19, 2008 11:27 AM
>>>>>> Subject: my token about the "3 or more layer" structure for the
>>>>>> ontology
>>>>>>> Hi everyone,
>>>>>>> I was at first very much in favor of an ontology that would
>>>>>>> distinguish
>>>>>>> different levels of media documents, like
>>>>>>> "work-manifestation-instance-item",
>>>>>>> but after reading this email from the list:
>>>>>>> http://lists.w3.org/Archives/Public/public-media-annotation/2008Nov/0076.html
>>>>>>> I agreed with the fact that we would probably only need a simple
>>>>>>> structure
>>>>>>> in
>>>>>>> our case, that multi-level structures were meant for linking
>>>>>>> different
>>>>>>> entities
>>>>>>> that have different status together: if we aim for linking the
>>>>>>> descriptions of a
>>>>>>> single item between different vocabularies, we need to specify if the
>>>>>>> single
>>>>>>> item is a work_in_XX_vocabulary, more likely a
>>>>>>> manifestation_in_XX_vocabulary
>>>>>>> (see note 1 below), to give its "type", and if people/use cases
>>>>>>> want to
>>>>>>> link
>>>>>>> this single item to other related works, manifestations, instances or
>>>>>>> items,
>>>>>>> they can use the framework defined in the schemas reviewed in
>>>>>>> http://www.w3.org/2008/WebVideo/Annotations/wiki/MultilevelDescriptionReview
>>>>>>> and use these properties for completing their description.
>>>>>>> So we would need a property like "has_type" to link a single
>>>>>>> description's
>>>>>>> identifier to the correct level of multilevel description schemes.
>>>>>>> I changed my mind think that only one "family" of use cases would
>>>>>>> need
>>>>>>> more
>>>>>>> levels, that they are somehow context dependent (and could thus be
>>>>>>> considered as
>>>>>>> requirements for a family of use cases), but of course if it turns
>>>>>>> out
>>>>>>> that more
>>>>>>> that one family of use cases needs this distinction, then we should
>>>>>>> consider
>>>>>>> going for a multilevel structure. Anyway, we would need to map
>>>>>>> informally
>>>>>>> the
>>>>>>> way these levels are expressed, in order to provide possible relevant
>>>>>>> "types"
>>>>>>> for the description of each single element.
>>>>>>> note 1: by specifying the different names of the relevant
>>>>>>> Concepts/terms
>>>>>>> in
>>>>>>> schemes like VRA, XMP etc., we would informally define a semantic
>>>>>>> equivalence
>>>>>>> between the ways these schema express these levels of description. It
>>>>>>> would look
>>>>>>> like:
>>>>>>> <metadataFile>
>>>>>>> <id="identifier">
>>>>>>> <hasType xmpMM:InstanceID, vra:image, frbr:item>
>>>>>>> </metadataFile>
>>>>>>> I think that the table
>>>>>>> http://www.w3.org/2008/WebVideo/Annotations/wiki/FeaturesTable
>>>>>>> is a very valuable tool for people to express their ideas about it,
>>>>>>> thank
>>>>>>> you
>>>>>>> very much Ruben for designing it!
>>>>>>> Best regards,
>>>>>>> Véronique
Received on Monday, 24 November 2008 13:45:10 UTC

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