The VOTable, VO Protocols, and UCDsJuan de Dios Santander Vela (IAA-CSIC)

Overview

VOTable, the VO table format

UCDs, UTypes, & column semantics

Simple DAL protocols

Simple ConeSearch

Simple Image Access

Simple Spectral Access

VOTable

VOTable

XML-based metadata (and sometimes, data) format

Allows for things which cannot be done with FITS

Semantic specification

Hierachical resource nesting

Linking (internal and to outside data)

VOTable StructureVOTABLE DESCRIPTION

0..1

DEFINITIONS

0..1

0..

COOSYS

PARAM

INFO

RESOURCE

0..

@ ID

@ version restricts: xs:NMTOKEN

VOTable: COOSYSCOOSYS extends: xs:string @ ID

type: ID from: XMLSchema.xsd

ID restricts: xs:NCName

@ equinox

type: astroYear

astroYear restricts: xs:token

@ epoch

type: astroYear

astroYear restricts: xs:token

@ system restricts: xs:NMTOKEN

base: string from: XMLSchema.xsd

string restricts: xs:anySimpleType whiteSpace : preserve

VOTable: RESOURCERESOURCE DESCRIPTION

0..1

0..

INFO

COOSYS

PARAM

LINK

0..

TABLE

0..

RESOURCE

0..

##other

0..

@ name

@ ID

@ utype

@ type restricts: xs:NMTOKEN

@ ##other

VOTable: TABLETABLE DESCRIPTION

0..1

0..

FIELD

PARAM

GROUP

LINK

0..

DATA

0..1

@ ID

@ name

@ ref

@ ucd

@ utype

@ nrows

VOTable: DATADATA TABLEDATA

BINARY

ref: BINARY

BINARY STREAM

FITS

ref: FITS

FITS STREAM

@ extnum

VOTable: TABLEDATA

TABLEDATA TR

0..

ref: TR

TR TD

1..

VOTable: STREAMSTREAM extends: xs:string @ type restricts: xs:NMTOKEN locator

other

base: NMTOKEN from: XMLSchema.xsd

NMTOKEN restricts: xs:token

@ href

@ actuate restricts: xs:NMTOKEN onLoad

onRequest

other

none

base: NMTOKEN from: XMLSchema.xsd

NMTOKEN restricts: xs:token

@ encoding

type: encodingType

encodingType restricts: xs:NMTOKEN gzip

base64

dynamic

none

base: NMTOKEN from: XMLSchema.xsd

NMTOKEN restricts: xs:token

@ expires

type: dateTime from: XMLSchema.xsd

dateTime

@ rights

type: token from: XMLSchema.xsd

token restricts: xs:normalizedString

base: string from: XMLSchema.xsd

string

Unified Content Descriptor

Unified Content Descriptor (UCD)

Extended unit

Provides broad-range semantics for table columns, and class equivalence

Mandatory attribute (@ucd) for VOTable FIELDs

UCD1+ Tree

arith (arithmetics)em (electromagnetic spectrum)instr (instrument)meta (metadata)obs (observation)phot (photometry)phys (physics)pos (positional data)spect (spectral data) src (source)stat (statistics)time

UTypes

UTypes are tools for direct mapping of columns into datamodels

Allows for VOTable serialisation or complex data models

Additional, optional FIELD attribute (@utype)

We will return to them when we talk about data models

VO Access ProtocolsAccess protocols == DAL protocols

Simple protocolsSimple to queryComplex to build, different protocol per data product type

Simple ConeSearch, Simple Image Access, Simple Spectral AccessCommon data model: CharDM

ConeSearch

endPointURL?RA=rightAscension& DEC=declination& SR=searchRadius& VERB=verbosity

CONESEARCH IS GENERIC:

TABLE FIELDS MUST BE IDENTIFIED

optional

mandatory

Simple Image AccessendPointURL?POS=RA,DEC&SIZE=searchRadius&FORMAT=formatType& INTERSECT=intersectionMechanism&NAXIS=axisSizeVector&CFRAME=coordFrame&EQUINOX=equinoxSpec&CRPIX=refPixCoordVector&CRVAL=refPixValueVector&CDELT=pixScaleVector&ROTANG=rotationAngle&PROJ=projectionKind&VERB=verbosity

optional

mandatory

Simple Spectra AccessendPointURL?POS=ra,dec& SIZE=searchRadius& BAND=freqRange& TIME=timeRange& FORMAT=formatType& SPECRP=specResol& SPATRES=spatialResol& PUBDID=pubID& CREATORDID=creatorID& COLLECTION=collectionID& TOP=topNumResults& MAXREC=maxRecords& MTIME=modificationTime& COMPRESS=compressionFlag& RUNID=jobRunID&

APERTURE=apertAngle& TIMERES=timeResol& SNR=signal2noise& REDSHIFT=redShiftRange& VARAMPL=amplitudeVariability& TARGETNAME=targetName& TARGETCLASS=targetClass& FLUXCALIB=fluxCalibKind& WAVECALIB=waveCalibKind

mandatory

optionalrecommended

VO Access Protocols

SxA Protocols simple to query

But they need a lot of client-side processing for filtering

Table Access Protocol

Direct access to tables

Complex REST interaction

REST:REpresentational State Transfer

References & LinksVOTable format

UCDs

UCD1+ list

UTypes

Simple ConeSearch

Simple Image Access

Simple Spectral Access

Table Access Protocol