VOEvent priorities

[Rob Seaman]

Hi Arnold and everybody else,

I may have misunderstood what you were saying - that is not the same  
thing as misrepresenting it.

Note that my message (below) was not intended to be responsive to one  
specific prior message.  Two-thirds of one paragraph out of nine total  
discusses STC.  As with most of my parenthetical remarks, omitting the  
sentence with WhatWhereWhen would have improved my point and made that  
paragraph shorter.  My pardon.

If minor restructuring and rewording is sufficient to make it pass  
muster on your end - by all means please work with John to make that  
happen.

The working group needs to focus on wrapping this up.  We reached a  
decision to add support for time series at HTU-1.  We reviewed all the  
options at HTU-2 and the various camps were clear.  Perhaps I failed  
in not serving out broadsides indiscriminately since HTU-2 to get the  
different camps to engage with the issues and with each other's points  
of view :-)

Rob
--

On Feb 3, 2010, at 3:43 PM, Arnold Rots wrote:

> This misrepresents what I was saying.
>
> I did not advocate putting everything into a massive WhereWhen (though
> that would be an obvious solution).
> I merely pointed out that SimpleTimeSeries does not follow adopted  
> standards.
> It could, with fairly minor restructuring and rewording.
> Or one could adopt the light-weight table schema that I suggested.
>
> Somehow, it seems to me that that message does not deserve a full
> broadside from the chair that seems to be missing the mark as well.
>
>  - Arnold
>
>
> Rob Seaman wrote:
>> Let me describe how this looks from the viewpoint of the chair.   
>> While
>> nobody values a robust discussion more than I do (anybody want to
>> challenge that assertion?), engineering choices must be timely or  
>> they
>> risk becoming moot.  This is the central message of VOEvent-based
>> science, after all.
>>
>> VOEvent is an IVOA standard, but the VOEvent community extends  
>> outside
>> of the IVOA context.  The people reading this email are the most
>> diverse of any IVOA WG - and yet we have found common ground where
>> other WGs have not, and done so time-and-again.  It concerns me that
>> some of our group have recently expressed private reservations about
>> the - hmm, how shall I say? - lack of timeliness of the IVOA process
>> in certain instances.
>>
>> The goal in systems engineering is not to find the optimum solution -
>> it is to find a satisfactory solution and then to actually implement
>> it.  We should keep this goal of "satisficing" (yes, a real word) in
>> mind throughout our discussions.  I might (and have, on occasion)
>> recommend the same to other WGs.
>>
>> VOEvent needs time series - which is to say that sufficient numbers  
>> of
>> our diverse user base need time series.  (And those who don't,  
>> needn't
>> use this v2.0 feature.)  A time series is a "thing" to be described
>> and so belongs in <What>.  Native STC usage in VOEvent is limited to
>> <WhereWhen> (where, for instance, orbital elements belong as  
>> targeting
>> coordinates for future observations).  So time series *in VOEvent
>> packets* will not use STC.  (And no, I don't see our combining
>> VOEvent's dependent variables with its independent variables into one
>> colossal <WhatWhereWhen> element.)
>>
>> We will not embed the VOTable schema within the VOEvent schema, so
>> time series *in VOEvent packets* will not use VOTable.  VOEvent can
>> already reference external content including VOTables, but external
>> references do not address the need to embed simple time series in
>> transient alert packets.
>>
>> On the other hand, the SimpleTimeSeries specification is satisfactory
>> - and can be made even more so through some small tweaks.  The team
>> that created SimpleTimeSeries has demonstrated that they are willing
>> to make said tweaks.
>>
>> Thus, our best approach to a usable solution is SimpleTimeSeries.  We
>> undoubtedly passed by other potential solutions on the road from  
>> HTU-1
>> to today.  There is no convincing argument to discard  
>> SimpleTimeSeries
>> and turn around to pursue these now.
>>
>> Now then, I thoroughly expect that the IVOA DAL group or some other  
>> WG
>> will pursue a "ComplicatedTimeSeries" specification at some point.
>> And perhaps in 3-5 years such a thing will exist - and perhaps it  
>> will
>> be based on STC or VOTable or both.  This will not be timely for our
>> purposes, and we have no way of knowing now whether the specification
>> resulting from such a process will be useful for our purposes.  If it
>> such a thing does add significant utility, then this can be supported
>> as a feature of a future VOEvent update.
>>
>> By all means, let's challenge SimpleTimeSeries with how it might
>> support various VOEvent use cases.  We should use our efforts to
>> improve the solution on the table, not to saw the legs out from under
>> it.
>>
>> Rob
>>
> --------------------------------------------------------------------------
> Arnold H. Rots                                Chandra X-ray Science  
> Center
> Smithsonian Astrophysical Observatory                tel:  +1 617  
> 496 7701
> 60 Garden Street, MS 67                              fax:  +1 617  
> 495 7356
> Cambridge, MA 02138                             arots at head.cfa.harvard.edu
> USA                                     http://hea-www.harvard.edu/~arots/
> --------------------------------------------------------------------------