Device Description definition

[Moving this to the public list because it is a technical issue.]

I have a preference for the second alternative definition of "Device Description" proposed by Kevin (see below), because it implies a plurality of information. However, there are still a few technical concerns (and I apologise for seeming overly pedantic but when it comes to formality, attention to detail is important).

- The "description" is not the enumeration itself, it is what is being enumerated. The description may comprise many parts. Collectively they may have some structure, and while it is likely possible to enumerate these parts, it is not a certainty that the enumeration will be unique.

- The preposition "of" appears three times. This could cause confusion.

- A capability is a property insofar as being an ability to perform, consume, use or otherwise take an action. So do we need to say "properties and capabilities" when "properties" will suffice?

- The phrase "parameters that define the properties" raises some questions. A "definition of a property" is something that captures the semantics associated with a property. For example, a property called "Physical Width" can have a definition that says "the maximum distance in meters between the horizontal extremities of the visible region of the display when viewed in its default orientation". I doubt we would think of this as a "parameter". I suspect we would probably think of "0.0025m" as a parameter. In other words, the value associated with the property.

- Regarding "generic instance of a specific device", I understand the intent, but the word "specific" is not sufficiently defined, and "generic" opens too many doors. Instead, I'm thinking more in the line of sets and set membership based on common properties. The descriptions would then capture the values of those common properties. This is a concept that would be less ambiguous than the use of specific/generic. Since we don't know how restrictive we may (or should) make the idea of a "specific" device, we might find it sufficient to refer to a set of devices. That leaves open the idea of defining the set, which is an issue that Jose is likely to encounter as he considers our Structures deliverable.

OK, enough. You can see why I apologised in advance for my pedantry.

So, do I have an alternative that fits with the spirit of the original text? Let's try this:

=== Device description - a collection of attribute-value pairs that apply to each member of a set of devices. ===

Now, we still have the issue of the definition of Device. As we all know, the issue of the physical/software duality of the client were raised during the workshop. We have no clear idea at this point in time how we should uniquely identify the client. Many physical units can support the same browser software, and many browsers can work on multiple hardware platforms. When a server receives a request, should we consider this a request from the physical device, the software device, or some hybrid? And is this hybrid identified in the request? Can we disambiguate? Can we avoid the combinatorial explosion that will result from the problem of identifying hybrids uniquely?

And finally, note that in the DI Glossary definition we find the word "apparatus", which some might assume means a physical entity, but of course an apparatus could equally be purely software or a combination. I believe this is why that particular word was used.

---Rotan.



From: member-ddwg On Behalf Of Smith, Kevin, VF-Group
Sent: 27 February 2007 17:41
To: member-ddwg
Subject: Device Description definition

Hi all,
 
As mentioned, here's my first attempt at a definition of 'Device description' for the DI glossary. Once it is agreed I can submit it to Rhys and we can refer to it from our documents.
 
Device description - a parameter that describes a single property and/or single capability of a generic instance of a specific device [1].
 
or 
 
Device description - an enumeration of the parameters that define the properties and capabilities of a generic instance of a specific device .
 
...the difference being that for the former, we imply a single descriptive item; for the latter, the collective description of a device's capabilities.
 
Notes:
- as the architecture evolves it may be that the definition changes to mention syntax or datatype (e.g. 'parameter' may change to 'attribute-value pair' or 'RDF-triple', etc.)
- the definition does not constrain the description to static properties only, should it?
 
Cheers,
Kevin
 

[1] Device is defined in the glossary as "An apparatus through which a user can perceive and interact with the Web" (http://www.w3.org/TR/di-gloss/#def-device) 
 
Kevin Smith
Technology Strategist
Vodafone Research & Development

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Received on Tuesday, 27 February 2007 21:36:10 UTC