[Architecture] Standards for defining value space in Registry

Christophe Strobbe strobbe at hdm-stuttgart.de
Wed Feb 20 14:14:49 EST 2013

Hi Antranig, All,

Am Mo, 18.02.2013, 21:23 schrieb Antranig Basman:
> (...) Our
> architectural plan has been to
> adopt as many of the provisions of JSON Schema where possible, and where
> not possible, to make modest
> specialised extensions. This standard has recently gone to a new IETF
> draft as of Jan 30th 2013, and the
> section which seems most relevant to your question is this:
> http://json-schema.org/latest/json-schema-validation.html

Thanks for reminding me of JSON Schema.
Is this something you recommend because much of the GPII architecture is
in JavaScript?

> The primitive types these rules are referred to are these:
> http://json-schema.org/latest/json-schema-core.html#anchor8
> Where values are scalars it seems they can be easily accommodated in this
> system. More complex types wuch as
> languages and colours would require appropriate references to other
> relevant specifications - for example
> last year I believe you determined that our choice for language value
> spaces would be covered by IETF BCP 47
> (mailing of Oct 11 2012)

Right. The kinds of data that may be stored as values is essentially
open-ended, and I think this has implications for the level of validation
we can expect to happen. For example, for language tags that should
conform to IETF BCP 47:
* a superficial check may be just checking that the tag is a string,
* a more thorough check may be a regular expression (which dialect??) that
checks against the language tag against the syntax described in IETF BCP
* the "grand cru" check (on top of checking syntax) would involve checking
that the value of each subtag in the language tag is valid, i.e. that it
is registered at the corresponding authority.

The last kind of check would be possible for certain known datatypes, but
most implementations would probably never go that far.

Any other thoughts?

Best regards,


> Thanks,
> Antranig
> On 18/02/2013 09:36, Christophe Strobbe wrote:
>> Hi,
>> In today's joint telecon on Registry terms, we added a new column to the
>> table with Registry fields to define what the format of each field
>> should
>> be. One of these fields is "ValueSpace": each term should have a
>> machine-readable definition of the value space. The next question then
>> is:
>> How do you write machine-readable descriptions of a value space. Values
>> may be colours (e.g. RGBA), integers, floating point numbers, text
>> strings
>> (from enumerated values), URIs, times of day, language identifiers,
>> brightness values, loudness values, etc etc etc.
>> It would be nice if we could reuse an existing standard or convention
>> instead of inventing our own. There are some standards that define ways
>> of
>> describing data types, like XML Schema Part 2
>> <http://www.w3.org/TR/xmlschema-2/> and the OpenAjax Metadata 1.0
>> Specification
>> <http://www.openajax.org/member/wiki/OpenAjax_Metadata_1.0_Specification_Datatypes>.
>> So I would like to ask if you know other standards that could be use for
>> this and request comments on how well they would fit our needs.
>> See the Value Space section in the wiki page about the Registry:
>> <http://wiki.gpii.net/index.php/Common_Terms_Registry#Value_Space>.
>> Best regards,
>> Christophe
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Christophe Strobbe
Akademischer Mitarbeiter
Adaptive User Interfaces Research Group
Hochschule der Medien
Nobelstraße 10
70569 Stuttgart
Tel. +49 711 8923 2749

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