Re: add "networkDuration" to Resource Timing

On Fri, Feb 27, 2015 at 10:38 AM, Todd Reifsteck <toddreif@microsoft.com>
wrote:

> Thanks, Ilya. The web interface is a bit tricky to navigate and I missed
> that response.
>
>
>
> To summarize and ensure I’m understanding the argument:
>
> If 3rd parties implemented
> http://www.w3.org/TR/resource-timing/#timing-allow-origin,
> networkDuration is not necessary because sufficient information would
> already be included.
>
>
>
> Is that accurate?
>

- For same origin resources you already have all the detailed metrics to
compute networkDuration.
- For first party origins you should enable TAO to get detailed metrics and
compute networkDuration from them.
- For third party origins that you don't control (correctly) exposing
networkDuration circumvents TAO [1].
- networkDuration is a noop for HTTP/2.

More generally, I think we should stay away from defining computed metrics
on the perf interface. Our job is to provide the raw timestamps, and we
should leave the rest to the application... networkDuration is just one of
many possible computed metrics [2] that we *could* expose, so it quickly
becomes a slippery slope of "why not also add X, Y, Z".

[1] https://lists.w3.org/Archives/Public/public-web-perf/2015Jan/0002.html
[2] https://lists.w3.org/Archives/Public/public-web-perf/2015Jan/0031.html