[Accessforall] [SP2] Conditional preferences

Clark, Colin cclark at ocadu.ca
Wed Aug 1 17:48:03 UTC 2012

Hey Andy,

On 2012-07-31, at 3:41 AM, Andy Heath wrote:
> What I do see in looking around cloud4all material is many instances of json structures that are not flat at all - they may follow a style similar to the existing 24751.  I see these being used as an
> argument that gpii has been implemented successfully.  I don't want
> to be controversial or denigrate anyone's work - I'm thrilled
> that something is working, but without agreement on these fundamental data formats  and their use in implementation I'm unsure how what's been implemented is different in kind from Web4all or any other implementation of 24751.
> Hopefully we are moving towards agreement on these "forms of data".

I hope I can provide some background information on our choices so far in terms of JSON structures.

We've been developing the GPII/Cloud4all architecture for a number of months now. When we started, very little consensus had yet been formed regarding a new structure for ISO 24751. This working group was still in the brainstorming phase. Similarly, the IMS 3 version of AccessForAll was still in flux and did not include any of the relevant preferences for assistive technology from the old Display and Control branches, so we couldn't use it, either.

But to get something working, we had to use something stable and documented, even if we knew it was going to change in the future. As a result, many of the example preferences documents in the system currently use the released version of ISO 24751. When the new structure for 24751 stabilizes to the point where it can be implemented (I think we're very close), we'll be updating these preferences profiles accordingly.

But we should also keep in mind our overall architectural approach: ISO 24751 and the flat registry will provide us with a shared, standard document structure for preferences. In addition, the Cloud4all preferences server will also be capable of producing transformations or "views" of a user's preferences in different structures, perhaps taking into account ontologies or different structures. This way, we get the benefits of a standard, interoperable structure while being able to easily produce alternative representations that are optimized for particular implementations or use cases.


Colin Clark
Lead Software Architect,
Inclusive Design Research Centre, OCAD University

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