16:58:12 <RRSAgent> RRSAgent has joined #webperf
16:58:12 <RRSAgent> logging to http://www.w3.org/2012/03/28-webperf-irc
16:58:14 <trackbot> RRSAgent, make logs world
16:58:14 <Zakim> Zakim has joined #webperf
16:58:16 <trackbot> Zakim, this will be WPWG
16:58:16 <Zakim> I do not see a conference matching that name scheduled within the next hour, trackbot
16:58:17 <trackbot> Meeting: Web Performance Working Group Teleconference
16:58:17 <trackbot> Date: 28 March 2012
17:00:54 <Alois> Alois has joined #webperf
17:01:48 <plh> plh has joined #webperf
17:02:04 <plh> zakim, this is per
17:02:04 <Zakim> ok, plh; that matches RWC_web-per()1:00PM
17:02:07 <Zakim> -[Microsoft]
17:02:07 <Zakim> +[Microsoft]
17:02:07 <Zakim> +Plh
17:02:44 <Zakim> + +43.664.853.aaaa
17:03:38 <Alois> Hi everyone
17:04:37 <JatinderMann> * Jatinder waves too
17:04:55 <simonjam> simonjam has joined #webperf
17:05:40 <Zakim> + +1.650.214.aabb
17:07:03 <JatinderMann> Topic: User Timing
17:07:48 <JatinderMann> Jatinder: "Throws a SYNTAX_ERR exception if either startMark or endMark argument, or both, have the same name as a PerformanceTiming attribute with a DOMHighResTimeStamp time value of 0."n
17:08:45 <plh> http://www.w3.org/TR/domcore/#exception-domexception
17:08:51 <JatinderMann> Jatinder: This exception protects from comparing against a Navigation Timing attribute that has been zero'd out due to cross-origin restrictions. If we allow this operation to occur, folks may get misleading data. I am in favor of raising an exception here, however, this isn't exactly a syntax error; this may better be a INVALID_STATE_ERR.n
17:10:05 <JatinderMann> plh: Would we consider this a security_err?
17:10:18 <JatinderMann> Jatinder: "The operation is insecure" doesn't sound accurate.
17:10:28 <plh> INVALID_ACCESS_ERR
17:10:41 <plh> "The object does not support the operation or argument. "
17:11:41 <JatinderMann> Alois: I think invalid_access_err should be the one. Because it is something that isn't supported.
17:12:05 <JatinderMann> James: We can just throw this one out there and see how folks react.
17:12:13 <JatinderMann> Jatinder: "Throws a SYNTAX_ERR exception if the duration (the end mark DOMHighResTimeStamp time value minus the start mark DOMHighResTimeStamp time value) is negative."n
17:12:43 <JatinderMann> The reason behind including this exception may have been to protect from comparing against a Navigation Timing attribute that has not yet loaded. E.g., performance.measure('measure1', 'navigationStart', 'loadEventEnd'), where the load event has not yet fired. 
17:12:54 <JatinderMann> Jatinder: However, the zero case above should cover the scenario where you are measuring against loadEventEnd but the load hasn't yet fired.
17:13:07 <JatinderMann> ...I think there is some value in being able to return negative measures. If I can do performance.measure('myMeasure', 'mark1', 'mark2') and getting all measures returns [5.0], then performance.measure('mymarkInverse', 'mark2', 'mark1') should return [-5.0].n
17:15:10 <JatinderMann> James: I think the negative case should be fine.
17:16:57 <JatinderMann> Jatinder: Sigjborn had feedback on whether we should even use exceptions.
17:17:20 <JatinderMann> James: plh, do we know if exceptions are still commonly used?
17:17:27 <JatinderMann> plh: Yes, they appear to be.
17:19:19 <JatinderMann> James: Between exceptions and negative numbers, I think we should just use exceptions.
17:24:07 <JatinderMann> Topic: High Resolution Time
17:25:27 <JatinderMann> Jatinder: There was feedback on whether we should change the resolution. We can either create an attribute that describes the User Agent's minimum resolution or change the recommended resolution.nnnWe change the spec text to say "MUST" return microsecond resolution. If hardware doesn't support millisecond resolution, or if high precision clocks are not available, then MUST return millisecond resolution. Most developers will just assume microseconds. 
17:28:29 <JatinderMann> We can either create an attribute that describes the User Agent's minimum resolution or change the recommended resolution.nnnWe change the spec text to say "MUST" return microsecond resolution. If hardware doesn't support millisecond resolution, or if high precision clocks are not available, then MUST return millisecond resolution. Most developers will just assume microseconds. Those that want to check can always 
17:30:00 <JatinderMann> ...or we can add an attribute that describes the resolution.
17:36:59 <Zakim> -[Microsoft]
17:37:00 <Zakim> - +1.650.214.aabb
17:37:00 <Zakim> -Plh
17:37:01 <Zakim> - +43.664.853.aaaa
17:37:01 <Zakim> RWC_web-per()1:00PM has ended
17:37:01 <Zakim> Attendees were [Microsoft], Plh, +43.664.853.aaaa, +1.650.214.aabb
17:38:02 <JatinderMann> Alois: I have had to do similar research on resolution of different systems, and I recommend that we shouldn't surface those complexities to the web platform. I recommend we don't add the attribute.
17:38:56 <JatinderMann> plh: We should add a "SHOULD" requirement in the spec and add a note that describes the scenario where sub-millisecond clock may not be available and what developers should do to determine that.
17:39:18 <JatinderMann> Jatinder: Okay, I will make those changes. Also, I think we should change the minimum resolution to microseconds.
17:39:23 <JatinderMann> James: Agreed.
17:40:19 <JatinderMann> Jatinder: Another piece of feedback was that performance.now() definition should make it clear that it does not remove the time of suspension when not fully active. Seems redudant to include that considering now defines the "current" time.
17:40:39 <JatinderMann> James: We may want to add a note in the spec to clarify the behavior. It doesn't have to be normative.
17:40:53 <JatinderMann> plh: You can also add an optional test case and it doesn't have to be required.
17:41:57 <JatinderMann> Jatinder: I will follow up on the mailing list.
17:42:28 <JatinderMann> Topic: Spec Status
17:42:52 <JatinderMann> plh: Considering WebIDL has moved to the next stage, we expect to bring Navigation Timing to PR in April.
17:43:26 <JatinderMann> Jatinder: With the latest Resource Timing change, we have no remaining open items on the spec. 
17:43:49 <JatinderMann> ... With the User Timing changes, we should be able to take this spec to LC. I will email you when I have made the final changes.
17:43:59 <JatinderMann> rrsagent, generate minutes
17:43:59 <RRSAgent> I have made the request to generate http://www.w3.org/2012/03/28-webperf-minutes.html JatinderMann
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