Re: Why ignoring unknown mandatory constraints is not stupid

On 18/11/13 21:57, Harald Alvestrand wrote:
> On 11/18/2013 09:36 PM, Jan-Ivar Bruaroey wrote:
>> On 11/17/13 11:40 PM, Harald Alvestrand wrote:
>>> Done: If I'm doing an application whose only purpose is analyzing houses
>>> for isolation hotspots, getting a non-thermal camera will just mean that
>>> I have to make code paths to deal with "this is a camera, but the data
>>> I'm getting from it is completely nonsensical". I don't want to spend
>>> time doing that.
>>
>> I'm not saying you have to. One line is all it takes:
>>
>>    if (!browser.getSupportedConstraints().hasOwnProperty("thermal"))
>> return false;
>>
>> This is an app decision.
>
> By the same token, why should this developer (who write apps for thermal
> cameras only) be the one to do that, and not the one who can live with a
> visible-light camera when his application is written for a thermal?
>
> The getSupportedConstraints() actually makes things a lot easier when
> dealing with constraints that the browser may or may not know, no matter
> whether the WG eventually agrees with me or with Jan-Ivar.
>
> But I think I'll stop posting on this subject. Let's hear from others.

Well, as you asked for it:

On the topic of gUM failing or not on unknown mandatory constraints
===================================================================
I come to the same conclusion as Harald. If we take the example of 
"zoom" (which seems the one just outside mandatory-to-support according 
to slide 24 in 
http://www.w3.org/wiki/images/f/fd/Constraints20130406.pdf): Assume my 
app for some reason must be able to control zoom (so it puts it as a 
mandatory constraint for gUM). If the browser doesn't understand "zoom", 
I am not helped by a success CB because the browser can't control the 
zoom - and that was a mandatory requirement for me.

On getSupportedConstraints
==========================
This is a really good proposal I think, we should introduce (something 
like) this.

On Mandatory constraints in general
===================================
I like the expressiveness of them, but I have two issues:
1. We do introduce some fingerprinting possibilities (20 questions)
2. I keep hearing that some OS's (that has a non negligible market 
share) just answer "yes, I can do that".
Would it make sense to go with only optional constraints for the first 
version?



>
>

Received on Tuesday, 19 November 2013 09:31:07 UTC