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[presentation-api] Drop step 6 of getAvailability for consistency with start?

From: François Daoust via GitHub <sysbot+gh@w3.org>
Date: Thu, 01 Dec 2016 16:27:45 +0000
To: public-secondscreen@w3.org
Message-ID: <issues.opened-192894550-1480609663-sysbot+gh@w3.org>
tidoust has just created a new issue for 
https://github.com/w3c/presentation-api:

== Drop step 6 of getAvailability for consistency with start? ==
That did not strike me as odd before, but why we do we need to call 
out the unability to "monitor the list of available presentation 
displays for the entire duration of the controlling browsing context" 
in step 6. of the [`getAvailability` 
algorithm](http://w3c.github.io/presentation-api/#getting-the-presentation-displays-availability-information)?

This concept does not exist in the `start` algorithm. In `start`, I 
think this is captured by the fact that the algorithm to [monitor the 
list of available presentation 
displays](http://w3c.github.io/presentation-api/#dfn-monitor-the-list-of-available-presentation-displays)
 will simply create an empty list of available presentation displays.

Following the same logic in `getAvailability`, given an empty list of 
available presentation displays, step 9. correctly returns a 
`PresentationAvailability` object whose `value` is set to `false` if 
the list of available presentation displays. In other words, step 6. 
seems useless to me.

A user agent may let users disable the ability to monitor the list of 
available presentation displays at any time. If that happens and 
there's already a list of available presentation displays, I would 
expect the user agent to run the monitoring algorithm once again (with
 an empty list of presentation displays) in the background. I'm not 
sure this needs to be made explicit in the spec given that we leave it
 up to implementers to run the monitoring algorithm again whenever 
they want, including "never" if they so choose.

Please view or discuss this issue at 
https://github.com/w3c/presentation-api/issues/383 using your GitHub 
account
Received on Thursday, 1 December 2016 16:27:56 UTC

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