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Re: Review of WebRTC Statistics from Web Performance Working Group

From: Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>
Date: Wed, 21 Dec 2016 13:57:26 +0000
To: Todd Reifsteck <toddreif@microsoft.com>, Ilya Grigorik <igrigorik@google.com>
CC: "public-web-perf@w3.org" <public-web-perf@w3.org>
Message-ID: <VI1PR0701MB27337A37742D1A97BE3154E1C9930@VI1PR0701MB2733.eurprd07.prod.outlook.com>
Hi Todd,

thanks for your input. I filed two issues to help us keep track:
https://github.com/w3c/webrtc-stats/issues/121
https://github.com/w3c/webrtc-stats/issues/120

Br,
Stefan

On 21/12/16 00:11, Todd Reifsteck wrote:
> 2 additional questions:
>
>   * It does not appear that this specification clearly defines when the
>     various Stat objects are created and what is responsible for
>     emitting the various Stat objects. Is another specification
>     responsible for that?
>       o It would be useful to link to that as it seems critical to
>         ensuring cross-browser compat.
>   * Some pieces of the text hint that a Stat object’s members can be
>     changed after it is returned. But an example shows 2 objects being
>     compared to see how a baseline compares to a later “report”. Can
>     stat object’s values be changed after they are returned?
>       o http://www.w3.org/TR/2016/WD-webrtc-stats-20161214/#lifetime-of-stats-objects
>         hints that an object that has been returned to JavaScript may
>         change between accesses, but I could be misreading it.
>
>
>
> -Todd
>
>
>
> *From:* Ilya Grigorik [mailto:igrigorik@google.com]
> *Sent:* Tuesday, December 20, 2016 11:52 AM
> *To:* Stefan Håkansson LK <stefan.lk.hakansson@ericsson.com>
> *Cc:* public-web-perf@w3.org; Todd Reifsteck <toddreif@microsoft.com>
> *Subject:* Re: Review of WebRTC Statistics from Web Performance Working
> Group
>
>
>
> Hi Stefan.
>
>
>
> On Wed, Dec 14, 2016 at 1:29 AM, Stefan Håkansson LK
> <stefan.lk.hakansson@ericsson.com
> <mailto:stefan.lk.hakansson@ericsson.com>> wrote:
>
>     Dear Web Performance Working Group,
>
>     The WebRTC Working Group is working toward publishing its WebRTC
>     Statistics API to Candidate Recommendation and is thus seeking review
>     from a variety of groups on the document:
>
>     https://www.w3.org/TR/2016/WD-webrtc-stats-20161214/
>
>     We are particularly interested on feedback from the Web Performance
>     Working Group on possible alignments needed between the names, value
>     spaces and design of the statistics exposed in our documents with the
>     ones the Web Performance Working Group has brought through its
>     various APIs.
>
>
>
> On a quick scan, I didn't spot any substantive problems. That said, a
> few nitpicks and thoughts:
>
>   * Provide a normative reference [1] for DOMHighResTimeStamp? Want to
>     make sure that time origin definitions are aligned across
>     implementations.
>   * Stats are associated with each stream, which means that application
>     developers have to manually instrument each stream. Is there a use
>     case for analytics / third-party instrumentation to gather similar
>     stats? E.g. it would be nice if existing RUM providers could
>     auto-gather stats without monkey-patching all the WebRTC APIs to
>     figure out when new streams are initiated, etc.
>
>       o Performance Timeline provides PerformanceObserver [2] interface
>         which allows anyone to register and listen for events. It might
>         be worth considering, if it makes sense, emitting some WebRTC
>         related events via this mechanism... which could stream specific
>         or aggregated.
>
> I'd be curious to hear from RUM vendors/folks if and how they currently
> instrument WebRTC.
>
>
>
> Cheers.
>
> ig
>
>
>
> [1] https://www.w3.org/TR/hr-time-2/#dom-domhighrestimestamp
>
> [2] https://www.w3.org/TR/performance-timeline-2/#the-performanceobserver-interface
>
Received on Wednesday, 21 December 2016 13:59:45 UTC

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