29-30 April 2004NVO Team Meeting NCSA1 Data Access Layer (DAL) SSA, SIA Enhancement Doug Tody National Radio Astronomy Observatory National Virtual Observatory

29-30 April 2004NVO Team Meeting NCSA2 Service Classes (Spectrophotometric Data) SEDAtlas or virtual SpectrumAtlas or virtual TimeSeriesAtlas or virtual

29-30 April 2004NVO Team Meeting NCSA3 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).

29-30 April 2004NVO Team Meeting NCSA4 Query Interface Required Query Parameters –posra,dec (IRCS) –sizediameter of aperture or search region –Formatany; xml,votable,fits,text; text/html; graphics; metadata

29-30 April 2004NVO Team Meeting NCSA5 Query Interface Optional Query Parameters –bandband1[,band2,...] (RSM) –timelower,upper (units?) –aperturemaximum or actual aperture size (arcsec) (default: size) –iddataset ID (global or service) –collectione.g., survey name –Classobject class –spectralClassspectral class (source attr) –redshiftlower,upper (source attr) –Verbosityquery response verbosity –rankall (default), top, N top items

29-30 April 2004NVO Team Meeting NCSA6 Query Response Rankdefault ordering of items (floating) Titledescriptive dataset title collectioncollection name, e.g., survey or instrument datasetIDglobal datasetID (query independent) logical namelogical dataset name (query relative) ra,decaperture center coordinates, IRCS apertureaperture diameter, arcsec time.refValuemean time of observation (MJD) time.loValstart of observation (MJD) time.hiValstart of observation (MJD) time.resolutionresolution of time signal (sec) spectral.IDfilter or bandpass name spectral.unitspectral unit spectral.refValuecharacteristic spectral value spectral.loVallower limit of bandpass spectral.hiValupper limit of bandpass spectral.resolutionspectral resolution formatspectra format (standard or collection-specific) AcrefURL used to access or retrieve dataset

29-30 April 2004NVO Team Meeting NCSA7 Service Metadata service class (SED, spectrum, timeSeries) service subclass (atlas or virtual data) supported formats supported query parameters max search aperture max object aperture

29-30 April 2004NVO Team Meeting NCSA8 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

29-30 April 2004NVO Team Meeting NCSA9 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.

29-30 April 2004NVO Team Meeting NCSA10 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)

29-30 April 2004NVO Team Meeting NCSA11

29-30 April 2004NVO Team Meeting NCSA12 Data Access Layer SIA V1.1 Priorities –Dataset provenance, Curation (collection, dataset ID) –UCD normalization, UTYPE –Logical name feature –Ranking feature –Error handling

29-30 April 2004NVO Team Meeting NCSA13

29-30 April 2004NVO Team Meeting NCSA14 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 Agree upon scope and plan for DAL catalog access service. 30-May-2004

29-30 April 2004NVO Team Meeting NCSA15 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 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 Draft SIA V1.1 spec available for review. 01-Aug Publish SIA V1.1 to REC status. 30-Nov-2004

29-30 April 2004NVO Team Meeting NCSA16 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 V0.9 working draft specification available for working group discussion and trials. 15-May V1.0 working draft specification available for review. 15-Jul Publish SSA V1.0 to REC status. 15-Nov-2004