Updates to NFC spec ...

Hi Luc,

It was a pity that you weren't able to make the face to face. Here is my 
summary of the changes that were discussed.

We feel that the use cases at the start of the document need a little 
expansion. This should be clear from the minutes. The bigger changes are 
in the API itself, where discussions with David Ezell suggested that we 
could simplify the API to avoid the possibility of race conditions and 
to simplify code that developers have to write.

In particular, he suggests dropping the powered and polling properties, 
and clarifying the error conditions. He asked what is the use case for 
powerOn without polling? If there isn't one you could make power on 
implicit with start polling.

We also discussed the scenario where the browser has several apps 
running concurrently on different Tabs and independently calling start 
and stop polling. In principle, apps could use the onstartpolling and 
onstoppolling methods to recover when another app stopped polling and 
the first app wants polling to be active.

However, a simpler alternative is for the underlying NFC manager to use 
a counter that is incremented on calls to start polling, and decremented 
on calls to stop polling unless the count is already zero. The NFC 
hardware only stops polling when the counter is decremented to zero. 
This way an app doesn't have to worry about whether other apps are 
starting and stopping polling.

This doesn't fully solve race problems when two apps respond to tag 
present events and independently write to the tag. In principle, we 
could introduce a resource lock, but we would then need to deal with 
recovering when an app crashes or closes without having released the 
lock or when it simply hangs on to the lock for an excessive time.

Any thoughts?

-------- Original Message --------
Subject: 	draft minutes of Shenzhen face to face
Date: 	Thu, 14 Nov 2013 08:07:01 +0000
From: 	Dave Raggett <dsr@w3.org>
To: 	public-nfc@w3.org


See: http://www.w3.org/2013/11/14-nfc-minutes.html

-- 
Dave Raggett<dsr@w3.org>  http://www.w3.org/People/Raggett

Received on Tuesday, 19 November 2013 12:55:41 UTC