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Subject: RE: [emergency-gis] RE: Question about CAP


Hi

I don't really understand what the issue is.  In my view, the "04:00" offset
in "2008-03-13T10:37:44-04:00" means that the intended time is 14:37:44 UTC.
Standard or daylight saving should be playing no role in this calculation.

I have to say that I don't know why we are allowing the use of nonzero
offsets (that is, timezones other than UTC) in CAP.  I don't see the
benefits of doing so, but I believe that it may cause confusion.  It should
be the message creator's responsibility to convert the local time (taking
account of daylight saving) to UTC when creating a message.

Alessandro


> -----Original Message-----
> From: Rex Brooks [mailto:rexb@starbourne.com] 
> Sent: Friday, March 14, 2008 17:15
> To: Paulsen,Norm [Ontario]; Rex Brooks; 
> emergency-gis@lists.oasis-open.org
> Subject: [emergency-gis] RE: Question about CAP
> 
> My pleasure, Norm,
> 
> These are important issues, so I am passing it along to the 
> appropriate working group, so disregard any bounces from your replies 
> to me.
> 
> Cheers,
> Rex
> 
> At 3:43 PM -0400 3/14/08, Paulsen,Norm [Ontario] wrote:
> >Thanks, they do frustrate....
> >
> >No more questions, just a few comments.
> >
> >The specifications use an example that is during daylight time and is
> >for the Pacific Time Zone (Art's own time zone). This offset 
> is -07:00
> >which would indicate that it does reflect the local time (daylight
> >adjusted) as PDT is 7 hours off in the summer and PST is 8 
> hours off in
> >the winter from UTC. This I read as contrary to your answer 
> below where
> >I could just take the value -4 and lookup the time zone.
> >
> >Unless I know the location and time zone particulars of the CAP
> >originating location though its useless to me as I would have to
> >maintain lookup tables for all originating sources and keep 
> them current
> >over time which is just a lot of unnecessary overhead that I wouldn't
> >want to deal with. With your way (I assume you mean -08 to 
> mean Pacific
> >time zone regardless of time of year) I can just look it up. 
> In truth I
> >prefer your way.
> >
> >The US is working with UTC in the <expires> and <effective> 
> tags by just
> >not using the offset in those fields. I tend to agree that 
> is the only
> >way to be safe and let the end recipient adjust for local time.
> >
> >I appreciate your time and answers. Maybe these questions 
> can be brought
> >up within the CAP working group.
> >
> >Thanks for listening.
> >
> >Norm
> >
> >-----Original Message-----
> >From: Rex Brooks [mailto:rexb@starbourne.com]
> >Sent: March 14, 2008 3:12 PM
> >To: Paulsen,Norm [Ontario]; emergency-gis@lists.oasis-open.org
> >Subject: RE: Question about CAP
> >
> >Hi Norm,
> >
> >I'm sorry if my answer frustrates, but the specification at stage 1.1
> >doesn't say anything directly on these specific issues. I have to use
> >what the specification actually says and apply it as best I can.  I'm
> >sorry I can't give you an authoritative answer.
> >
> >My best advice at this point is to take the <sent> dateTime value for
> >the CAP MessageID and consider it as defining the Time Zone of the
> >issuing agency/office.
> >
> >In regard to case you cite for an <effective> dateTime before a time
> >change and an <expires> afterward, these values are defined 
> only for the
> ><area> associated with the <info> element, so you should  be able to
> >look up the Time Zone based on the <area>. This is not 
> dependent on the
> >location of the CAP issuing office.
> >
> >I'm doing my best to answer your questions. I apologize, if that's
> >insufficient.
> >
> >Cheers,
> >Rex
> >
> >
> >
> >>THANKS
> >>
> >>FOLLOW UP QUESTIONS WHICH ARE MORE TO MY ISSUE
> >>
> >>1) REGARDLESS OF TIME OF YEAR ... IS <sent> THE CURRENT LOCAL TIME?
> >>...OR IS IT LOCAL STANDARD TIME?
> >>
> >>2) The <effective> and <expires> TAGS ARE FORMATTED THE 
> SAME AS <sent>
> >>SO IF THE <effective> TIME IS BEFORE THE DAYLIGHT TIME 
> CHANGE AND THE
> >><expires> IS AFTER TIME CHANGE IS THE RECIPIENT EXPECTED TO 
> KNOW THIS
> >>AND SEE THIS REFLECTED IN THE TAG VALUE?
> >>
> >>3) WHAT'S THE POINT OF KNOWING THE LOCAL TIME OF THE CAP 
> ISSUING OFFICE
> >
> >>IF THE LOCATION OF THE CAP ISSUING OFFICE IS NOT KNOWN. I 
> DON'T SEE A
> >>TAG THAT GIVES THAT INFO SO WHAT'S THE POINT OF KNOWING THE 
> LOCAL TIME
> >>OF THE CAP ISSUING OFFICE?
> >>
> >>NORM
> >>
> >>
> >>-----Original Message-----
> >>From: Rex Brooks [mailto:rexb@starbourne.com]
> >>Sent: March 14, 2008 12:18 PM
> >>To: Paulsen,Norm [Ontario]; Rex Brooks
> >>Cc: Elysa Jones
> >>Subject: RE: Question about CAP
> >>
> >>Hi Norm, Elysa,
> >>
> >>I was afraid this might be the issue. NOAA-NWS is slightly
> >>non-conformant, so you would have to ask them about the details of
> >>their implementation. The dateTime for <sent> SHOULD be for the
> >>location of the sender at the time the message was issued and
> >>identified by the MessageID. That would, most likely, be for the
> >>CAP-issuing office location as you infer.
> >>
> >>
> >>
> >>
> >>However, when the message is issued by NOAA, I believe, 
> though I could
> >  >be wrong, that the <sent> dateTime is for the NOAA-NWS HQ 
> through which
> >
> >>alert messages are issued. That would account for the same offset in
> >  >California and New York.
> >>
> >>You are correct. The <alert> <sent> dateTime is for the message, not
> >>for the <area> associated with the <info> which contains the Onset
> >>Date/Time
> >>(onset) and Effective Date/Time (effective) directly related to the
> >>incident/event.
> >>
> >>I hope that helps.
> >>
> >>Cheers,
> >>Rex
> >>
> >>
> >>At 11:20 AM -0400 3/14/08, Paulsen,Norm [Ontario] wrote:
> >>>Rex
> >>>
> >>>Thanks for the response and the offer to help....
> >>>
> >>>It is the <sent> tag in the <alert> block..
> >>>
> >>>Couple of U.S. examples below...
> >>>
> >>><alert>
> >>>	<identifier>
> >>>	NOAA-NWS-ALERTS California 2008-03-13T10:37:44-04:00
> >>>	</identifier>
> >>>	<sender>w-nws.webmaster@noaa.gov</sender>
> >>>	<sent>2008-03-13T10:37:44-04:00</sent>
> >>>	<status>Actual</status>
> >>>	<msgType>Alert</msgType>
> >>>	<scope>Public</scope>
> >>>	<note>
> >>>		Current Watches, Warnings and Advisories for California
> >>Issued by the
> >>>National Weather Service
> >>>	</note>
> >>>	<references>
> >>>	http://www.weather.gov/alerts/ca.html
> >>>	</references>
> >>>	<info> .... </info>
> >>>	<info> .... </info>
> >>>	<info> .... </info>
> >>>	<info> .... </info>
> >>></alert>
> >>>
> >>>And the same for New York State:
> >>>
> >>><alert>
> >>>	<identifier>
> >>>	NOAA-NWS-ALERTS New York 2008-03-13T10:42:25-04:00
> >>>	</identifier>
> >>>	<sender>w-nws.webmaster@noaa.gov</sender>
> >>>	<sent>2008-03-13T10:42:25-04:00</sent>
> >>>	<status>Actual</status>
> >>>	<msgType>Alert</msgType>
> >>>	<scope>Public</scope>
> >>>	<note>
> >>>	Current Watches, Warnings and Advisories for New York Issued by
> >>the
> >>>National Weather Service
> >>>	</note>
> >>>	<references>
> >>>	http://www.weather.gov/alerts/ny.html
> >>>	</references>
> >>>	<info> .... </info>
> >>>	<info> .... </info>
> >>>	<info> .... </info>
> >>>	<info> .... </info>
> >>></alert>
> >>>
> >>>Both have -04:00 as the time zone modifier. The 
> <identifier> tag notes
> >>   >California for one alert and New York for the other alert.
> >>>
> >>>Since they are both -04:00, I assume the <sent> tag is referring to
> >>>the
> >>
> >>>time it was in the location of the office where the CAP alert was
> >>>generated regardless of where the hazard was for. Looks like an
> >>>Eastern
> >>
> >>>time zone based on -04.
> >>>
> >>>If true, to know if -04:00 is EDT (Eastern Daylight)or AST 
> (Atlantic
> >>>Standard) I would need to know the location of the CAP 
> issuing office.
> >>>The CAP standard document uses a Daylight example so it appears its
> >>>not
> >>
> >>>just a local standard time offset, but assuming I even 
> have a need to
> >>>know the time at the location of the issuing office how 
> would I know
> >>>which one it is?
> >>>
> >>>Is there a place to tag the location and timezone of the issuing
> >>>office
> >>
> >>>without having to resort to a local lookup table? A lookup 
> table would
> >
> >>>require maintenance which could more easily be done with a tag for
> >>>this
> >>
> >>>info.
> >>>
> >>>In the end, daylight or not, UTC can be properly calculated but if
> >>>someone in California were to disseminate it locally, they 
> would have
> >>>to work from <sent> to UTC to Pacific time or use what is 
> later found
> >>>in the <description> tag???
> >>>
> >>>If this is how its meant to be, what's the point? If I need to know
> >>>the
> >>
> >>>local time at the issuing office then I would need to know the time
> >>>zone of the issuing office so as to properly process this 
> information.
> >>>
> >>>However, if I don't need to know (and I haven't a reason 
> figured out
> >>>yet why I would), why not just put UTC time in the <sent> tag.
> >>>
> >>>Thanks
> >>>Norm
> >>>
> >>>-----Original Message-----
> >>>From: Rex Brooks [mailto:rexb@starbourne.com]
> >>>Sent: March 14, 2008 10:54 AM
> >>>To: Elysa Jones; Rex Brooks
> >>>Cc: Paulsen,Norm [Ontario]
> >>>Subject: Re: Question about CAP
> >>>
> >>>Hi Norm,
> >>>
> >>>I would be happy to answer your question. However, I'm not 
> sure what
> >>>is
> >>
> >>>referred to by "offset value" and to which element is 
> applied. I did a
> >
> >>>quick search of the document and neither 'offset' nor 
> 'offset value'
> >>>occurs in the document, so I am assuming that you are 
> referring to a
> >>>specific implementation issue, so if you could clarify 
> that for me, I
> >>>will do my best to answer.
> >>>
> >>>Cheers,
> >  >>Rex
> >>>
> >>>At 8:39 AM -0500 3/14/08, Elysa Jones wrote:
> >>>>Rex,
> >>>>
> >>>>Meet Norm Paulsen of Environment Canada.   We were on a call today
> >  >>>with Norm's organization and OASIS staff.  They are 
> interested in
> >>>>joining us to participate with the CAP usage issues, as 
> well as other
> >
> >>>>EDXL standards.
> >>>>
> >>>>He has an immediate question about the CAP Element Tag 
> wrt the offset
> >
> >>>>value and why it is determined as it is.  He is working an issue
> >>>>right
> >>
> >>>>now and I thought you would be best able to give him an answer.
> >>>>Please
> >>>
> >>>>get in touch with Norm if you can.
> >>>>
> >>>>Thanks,
> >>>>Elysa
> >>>
> >>>
> >>>--
> >>>Rex Brooks
> >>>President, CEO
> >>>Starbourne Communications Design
> >>>GeoAddress: 1361-A Addison
> >>>Berkeley, CA 94702
> >>>Tel: 510-898-0670
> >>
> >>
> >>--
> >>Rex Brooks
> >>President, CEO
> >>Starbourne Communications Design
> >>GeoAddress: 1361-A Addison
> >>Berkeley, CA 94702
> >>Tel: 510-898-0670
> >
> >
> >--
> >Rex Brooks
> >President, CEO
> >Starbourne Communications Design
> >GeoAddress: 1361-A Addison
> >Berkeley, CA 94702
> >Tel: 510-898-0670
> 
> 
> -- 
> Rex Brooks
> President, CEO
> Starbourne Communications Design
> GeoAddress: 1361-A Addison
> Berkeley, CA 94702
> Tel: 510-898-0670
> 
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