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Data Access Layer (DAL) SSA, SIA Enhancement

National Virtual Observatory. Data Access Layer (DAL) SSA, SIA Enhancement. Doug Tody National Radio Astronomy Observatory. Service Classes (Spectrophotometric Data). Query Interface. Query Types FindSED FindSpectrum FindTimeSeries

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Data Access Layer (DAL) SSA, SIA Enhancement

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  1. National Virtual Observatory Data Access Layer (DAL)SSA, SIA Enhancement Doug Tody National Radio Astronomy Observatory NVO Team Meeting NCSA

  2. Service Classes (Spectrophotometric Data) NVO Team Meeting NCSA

  3. Query Interface • Query Types • FindSED • FindSpectrum • FindTimeSeries Any of SOAP, GET, POST depending upon service capabilities. Support for GET is required; SOAP and POST are optional. Query is the same regardless of the transmission protocol. Query response (a VOTable) may differ for each class of object. Each type of service is registered separately. All queries have the same basic arguments (so far). NVO Team Meeting NCSA

  4. Query Interface • Required Query Parameters • pos ra,dec (IRCS) • size diameter of aperture or search region • Format any; xml,votable,fits,text; text/html; graphics; metadata NVO Team Meeting NCSA

  5. Query Interface • Optional Query Parameters • band band1[,band2,...] (RSM) • time lower,upper (units?) • aperture maximum or actual aperture size (arcsec) (default: size) • id dataset ID (global or service) • collection e.g., survey name • Class object class • spectralClass spectral class (source attr) • redshift lower,upper (source attr) • Verbosity query response verbosity • rank all (default), top, N top items NVO Team Meeting NCSA

  6. Query Response • Rank default ordering of items (floating) • Title descriptive dataset title • collection collection name, e.g., survey or instrument • datasetID global datasetID (query independent) • logical name logical dataset name (query relative) • ra,dec aperture center coordinates, IRCS • aperture aperture diameter, arcsec • time.refValue mean time of observation (MJD) • time.loVal start of observation (MJD) • time.hiVal start of observation (MJD) • time.resolution resolution of time signal (sec) • spectral.ID filter or bandpass name • spectral.unit spectral unit • spectral.refValue characteristic spectral value • spectral.loVal lower limit of bandpass • spectral.hiVal upper limit of bandpass • spectral.resolution spectral resolution • format spectra format (standard or collection-specific) • Acref URL used to access or retrieve dataset NVO Team Meeting NCSA

  7. Service Metadata • service class (SED, spectrum, timeSeries) • service subclass (atlas or virtual data) • supported formats • supported query parameters • max search aperture • max object aperture NVO Team Meeting NCSA

  8. Error Status • SIA returns a VOTable containing an error code, if an error occurs. • Should we return a HTTP error status instead of a VOTable? • Error return for query is different than that for the dataset access NVO Team Meeting NCSA

  9. SSA (Spectrophotometry?) Data Model • At core is a Spectrophotometry object • Spectrum subclass has constant time and position • TimeSeries subclass has constant spectral coordinate • SED is a set of Spectrum objects • Curation, Coverage, Accuracy, Frame • SpectralCoordinate object • type: wavelength, frequency, energy, etc. • Flux object • type: flux density, intensity, counts, etc. NVO Team Meeting NCSA

  10. SSA Data Formats • VOTable • standard table format, extensible • one table per spectrum • FITS • standard table format, extensible • bintable with row-per-spectrum for SED • XML • native XML, for web services and XML tools • text • simple text (no markup) NVO Team Meeting NCSA

  11. NVO Team Meeting NCSA

  12. Data Access Layer • SIA V1.1 Priorities • Dataset provenance, Curation (collection, dataset ID) • UCD normalization, UTYPE • Logical name feature • Ranking feature • Error handling NVO Team Meeting NCSA

  13. NVO Team Meeting NCSA

  14. DAL Roadmap • Simple Catalog Access • Scope: Simple queries to individual catalogs (e.g., CS, SkyQuery) • More complex catalog operations, e.g., query portals, distributed • cross-matching, etc., are handled elsewhere within VO. • Status: Current interface is Cone Search with no QL. • Relevant work is currently going on within the ADQL WG; we need • to determine how to recast portions of this as a DAL service. • 1. Discuss plan for DAL integration of ADQL/SkyNode technology • at NVO team meeting Apr 30 for review by DAL WG at the May 24 • Interop meeting. • 30-Apr-2004 • 2. Agree upon scope and plan for DAL catalog access service. • 30-May-2004 NVO Team Meeting NCSA

  15. DAL Roadmap • Simple Image Access (SIA) • Scope: Access to 1-2D images and spectral image cubes. • Status: Defacto V1.0 of the SIA interface is in use but has • not yet been published as an IVOA standard. • 1. Publish SIA V1.0 in its current form as a grand-fathered • (frozen) interface. • 31-Mar-2004 • 2. Agree on feature set for SIA V1.1 (limited to relatively minor • enhancement of V1.0). Begin discussion of requirements for general • image access beyond SIA. • 30-May-2004 • 3. Draft SIA V1.1 spec available for review. • 01-Aug-2004 • 4. Publish SIA V1.1 to REC status. • 30-Nov-2004 NVO Team Meeting NCSA

  16. DAL Roadmap • Simple Spectral Access (SSA) • Scope: 1D spectra, SEDs, time series. • Status: Have internal V0.1 versions of query interface and • spectral data model. Working drafts still in preparation within • subgroups. • 1. V0.5 working draft specification available for working group • discussion and trials. • 15-Apr-2004 • 2. V0.9 working draft specification available for working group • discussion and trials. • 15-May-2004 • 3. V1.0 working draft specification available for review. • 15-Jul-2004 • 4. Publish SSA V1.0 to REC status. • 15-Nov-2004 NVO Team Meeting NCSA

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