W3C home > Mailing lists > Public > public-media-capture@w3.org > November 2011

Callback style for GetUserMedia (Re: First draft available)

From: Harald Alvestrand <harald@alvestrand.no>
Date: Wed, 30 Nov 2011 22:42:31 +0100
Message-ID: <4ED6A347.8080003@alvestrand.no>
To: Anant Narayanan <anant@mozilla.com>
CC: Robin Berjon <robin@berjon.com>, Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>, public-media-capture@w3.org
On 11/30/2011 07:17 PM, Anant Narayanan wrote:
> On Nov 30, 2011, at 8:31 AM, Harald Alvestrand wrote:
>> On 11/30/2011 12:38 PM, Robin Berjon wrote:
>>> Why is the title "getusermedia" when the method is getUserMedia? Perhaps a simpler, shorter title would work better. I don't want to bikeshed and think the editors should make the call, but maybe Media Capture API, or Local Media Capture API?
>>> getUserMedia() uses the success/error callback approach, which is increasingly disliked.
>> By whom?
>> This is the first time I've heard this comment, and the function has already been implemented in Chrome/Webkit, Firefox, Opera and Ericsson's Webkit-based experiment; I would have expected someone to comment on the style before now if the sentiment is widespread.
> This particular comment has been brought up before in the WebRTC mailing list (ref: http://lists.w3.org/Archives/Public/public-webrtc/2011Oct/0002.html second point). I agree that the current callback mechanism is not very elegant. Both the event handler and node.js style callback are suitable replacements.
Thanks for the pointer - I didn't associate that comment with this issue 
because that comment suggested returning the stream directly from 
GetUserMedia, and this was rejected by the WG discussion (according to 
my reading).

>>> Or the Node-style compound callback:
>>> navigator.getUserMedia(options, function (err, stream) {...});
>> As far as I can tell, this is completely equivalent to the success/error callback, except that you have written the callback as an anonymous function and put the job of distinguishing between success and callback within the function. What is the advantage of this approach?
> The function doesn't have to be anonymous. The main advantage of this approach is that there is only one callback that handles both success and failure, instead of two.

I'm a bit dense, but please bear with me .... what is the reason why 
this is an advantage?
Received on Wednesday, 30 November 2011 21:43:05 UTC

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