[ResourceTiming] A few small things

Hi folks,

A few thoughts about the current draft @ http://www.w3c-test.org/webperf/specs/ResourceTiming/

1. We've discussed the differences between ResourceTiming's startTime<http://www.w3c-test.org/webperf/specs/ResourceTiming/#performance-resource-timing> and fetchStart<http://www.w3c-test.org/webperf/specs/ResourceTiming/#fetch-start> before, but I think there is still a bit of confusion.  Ignoring redirects for a moment, startTime is currently defined as "The startTime attribute must return the time immediately before the user agent starts to queue the resource for fetching".  In a recent discussion with James [1], we talked about startTime always equaling fetchStart for non-redirection scenarios.  However, we had also previously talked about startTime possibly being earlier than fetchStart, in the case that the browser queued a resource for download but does not immediately attempt to fetch it because of connection limits.  For example, if you included 100 <img>s all on the same domain, the resources may all have a similar startTime (parsing HTML is fast), but their fetchStarts would differ on the later <img>s as connections became available.  I believe the wording of startTime in the spec currently supports this notion, but I wanted to make sure everyone agreed that was the intention?

2. For consistency, can we rename INITIATOR_IMAGE<http://www.w3c-test.org/webperf/specs/ResourceTiming/#sec-window.performance-attribute> to INITIATOR _IMG?  All of the other initiator names use the HTML element name or concept, and IMAGE seems a bit ambiguous when it really only means the <IMG> tag.

3.  The most popular initiator<http://www.w3c-test.org/webperf/specs/ResourceTiming/#sec-window.performance-attribute> that I see on the web that currently falls under INITIATOR_OTHER is input[type='image'].  The second most popular is body[background='...'].  We could add INITIATOR_INPUT and INITIATOR_BODY, though I don't feel strongly that we need them.

- Nic

[1] [Resource Timing] Spec feedback, dated Wed 8/31/2011 12:50 PM