Data and services

[Wil O'Mullane]

but as we also discussed this is almost the same as learning to type the XML :(
wil
On Thu, Sep 18, 2003 at 05:32:32PM -0400, Arnold Rots wrote:
> Bob,
> 
> A while ago you asked about how to describe regions in a non-XLM
> format.  It occurred to me that Wil and I had a discussion that might
> be helpful for your purposes.  See the attached memo.
> It was written for the query element, but I have attached a version
> for the resource profile.
> 
> Another issue you raised was about how to handle limit transitions in
> cyclical coordinates in the specification of polygons (like: which way
> around when you go from RA=300 to RA=100).
> I can see two solutions to this:
> 1. Allow values less than 0 as well as greater than 360:
> - the example above would mean going "to the right"
> - had you wanted to go the other way, you should have specified RA=300
> to RA=460
> 2. Do not allow circle segments that are 180 degrees or more:
> - the example would mean going "to the left"
> - the other way would have required an intermediate point at, say, RA=200
> I like (1) better and it is also easier to specify, but I suspect that
> (2) is easier to parse.
> 
>   - Arnold
> 
> 
> Robert Hanisch wrote:
> > 
> > ----- Original Message ----- 
> > From: "Tony Linde" <ael at star.le.ac.uk>
> > To: "'Ray Plante'" <rplante at poplar.ncsa.uiuc.edu>; "'Robert Hanisch'"
> > <hanisch at stsci.edu>
> > Cc: <registry at ivoa.net>
> > Sent: Friday, September 12, 2003 3:18 PM
> > Subject: RE: Data and services
> > 
> > 
> > > I'd forgotten about Coverage. Maybe SkyService should stay so that when
> > > solar and stp people create their schemas they can have a SolarService and
> > > STPService.
> > >
> > > Maybe we need a DataService which includes a pointer to the root data
> > > collection plus any other data-ish metadata and then SkyService,
> > > SolarService and STPService can inherit from that?
> > That might be ok.  Though perhaps we don't have to build this structure just
> > yet.
> > 
> > > And should Coverage be renamed to SkyCoverage? Or is there enough
> > > commonality between 'coverage' in the disciplines to deal with the
> > > differences with one or two optional elements?
> > Solar, Planetary, and STP will have different concepts for coverage.
> > 
> > Bob
> > 
> --------------------------------------------------------------------------
> 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/
> --------------------------------------------------------------------------
> 
> Incorporating STC Structures in VO Queries
> ==========================================
> 
> 
> Define the following parameters (purely for convenience):
> 
> define CSys =  (TimeFrame = (TimeScale='TT') and (TimeRefPosition='TELESCOPE'))
>            and (SpaceFrame = (CoordFrame='ICRS') and (CoordRefPosition='TELESCOPE'))
>            and (SpectralFrame = 'OBSERVATORY')
>            and (CoordFlavor = 'SPHERICAL')
> 
> define CArea = (TimeInterval = (StartTime=(ISOTime='2000-01-01'))
>                            and (StopTime=(ISOTime='2002-12-31')))
>            and (Region = (Circle = (Center='60.0d,30.0d') and (Radius='10arcmin'))
>                       or (Polygon = ((Vertex='23.0d,46.0d'),(Vertex='20.0d,46.0d')
>                                      (Vertex='20.0d,48.0d'),(Vertex='23.0d,48.0d'))))
>            and (SpectraLinterval = (LoLimit='1GHz') and (HiLimit='2GHz'))
> 
> define CSpec = (Time = (CoordResolution<='10s'))
>            and (Pos2Vector = (CoordResolution<='10arcsec,10arcsec'))
>            and (Spectrum = (CoordResolution<='50MHz'))
> 
> 
> Specify the query:
> 
> select <SelectList> from <ResourceList> where <WhereClauses> and
>   SearchLocation = (CoordSystem = $CSys and CoordArea = $CArea
>     [ and CoordSpec = $CSpec ])
> 
> 
> One could, of course, imagine pre-defining some defaults.
> 
> 
> If one were to encapsulate the STC part in an XML document, the query
> would reduce to:
> 
> select <SelectList> from <ResourceList> where <WhereClauses> and
>   SearchLocation = (http://MyPlace/MySearchLocation.xml)
> 
> 
> 
> Or one could make a hybrid:
> 
> select <SelectList> from <ResourceList> where <WhereClauses> and
>   SearchLocation = ((CoordSystem = http://nvo.org/standardCoordSys.xml)
>     and CoordArea = $CArea [ and CoordSpec = $CSpec ])
> 
> 
> 
> Resource Profile
> ================
> 
> Specify the coverage:
> 
>   ResourceProfile = (CoordSystem = $CSys and CoordArea = $CArea and CoordSpec = $CSpec)
> 
> where:
> 
> define CSys =  (TimeFrame = (TimeScale='TT') and (TimeRefPosition='TELESCOPE'))
>            and (SpaceFrame = (CoordFrame='ICRS') and (CoordRefPosition='TELESCOPE'))
>            and (SpectralFrame = 'OBSERVATORY')
>            and (CoordFlavor = 'SPHERICAL')
> 
> define CArea = (TimeInterval = (StartTime=(ISOTime='1999-07-23')))
>            and (Region = (Circle = (Center='60.0d,90.0d') and (Radius='180d')))
>            and (SpectraLinterval = (LoLimit='0.1keV') and (HiLimit='12keV'))
> 
> define CSpec = (Time = (CoordResolution>='0.000016s'))
>            and (Pos2Vector = (CoordResolution>='0.5arcsec,0.5arcsec'))
>            and (Spectrum = (CoordResolution>='2eV'))
> 
> 
> Or do it in one expression::
> 
>   ResourceProfile = (CoordSystem =
>                (TimeFrame = (TimeScale='TT') and (TimeRefPosition='TELESCOPE'))
>            and (SpaceFrame = (CoordFrame='ICRS') and (CoordRefPosition='TELESCOPE'))
>            and (SpectralFrame = 'OBSERVATORY')
>            and (CoordFlavor = 'SPHERICAL')
>                      and CoordArea =
>                (TimeInterval = (StartTime=(ISOTime='1999-07-23')))
>            and (Region = (Circle = (Center='60.0d,90.0d') and (Radius='180d')))
>            and (SpectraLinterval = (LoLimit='0.1keV') and (HiLimit='12keV'))
>                      and CoordSpec =
>                (Time = (CoordResolution>='0.000016s'))
>            and (Pos2Vector = (CoordResolution>='0.5arcsec,0.5arcsec'))
>            and (Spectrum = (CoordResolution>='2eV')))
> 
> It's not as bad as it looks at first, and it translates easily into
> STC XML elements.