Re: Conclusions from the constraints spec review

On Fri, Feb 7, 2014 at 10:56 AM, Harald Alvestrand <harald@alvestrand.no>wrote:

> After reading through the messages sent on this topic, and after
> consulting with the editors, the chairs have reached the following
> conclusions and action plans:
>
> - We will keep the Constrainable interface, with the current structure.
> - We will make one registry of constraints, common across all usages.
> - We will change the type of ConstraintSet to be a typedef of Object.
>
> Details on each of these:
>
> The trigger for breaking out the Constrainable interface was a request
> from Jim (editor of MediaStreamRecorder) to have an interface he could
> reuse, rather than having to respecify constraints from scratch if he
> wanted to reuse the pattern.
> We believe the breaking out makes the interface reusable, as requested,
> and also makes the specification clearer and easier to read. Both are wins.
>

You have focused on the benefits to specifiers, who are near the bottom of
the "priority of constituencies":
http://www.w3.org/TR/html-design-principles/#priority-of-constituencies
Using Constrainable for MediaRecorder places burdens on implementors (e.g.
having to implement mandatory constraints and applyConstraints() for
MediaRecorder, when no case has been made for them being valuable in their
own right). It also places burdens on authors for the reasons I raised
previously. And as a reader of the MediaRecorder specification, I do not
find that having to refer to the separate Constrainable spec and IANA
registry --- and wade through the parts irrelevant to MediaRecorder ---
makes it easier to read.

I would like to ask the W3C TAG to consider these issues and offer their
opinion. Do you have any objection to that? We did this for some
contentious issues in Web Audio and it worked well.

Rob
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