October 12, 2003ADASS NVO Tutorial 1

How-To ImplementCone and SIA Serviceshttp://www.us-vo.org/standards.html

Gretchen GreeneSpace Telescope Science Institute

THE US NATIONAL VIRTUAL OBSERVATORY

October 12, 2003ADASS NVO Tutorial 2

First Standard for VO

• CONE service– Circular area query to a catalog– HTTP GET– Returns VOTable– Requires

• <BaseURL>?RA=....&DEC=....&SR=– Optional verbs allowed (see example below)

• Cone Service metadata retrieval– SR=0

• Example (used in Galaxy Morphology NVO Demo)http://nedwww.ipac.caltech.edu/cgi-bin/nph-nedconez?RA=194.95305&DEC=27.98069&SR=0.8&TYPE=G&ZMIN=0.01&ZMAX=0.03

• Prototype service registries available– http://sdssdbs1.stsci.edu/nvo/registry/index.aspx – http://rai.ncsa.uiuc.edu/nvoregistration.html (OAI)

October 12, 2003ADASS NVO Tutorial 3

Sample Cone Search VOTable

FOR SR=0 you will see FIELD. i.e. metadata info only

October 12, 2003ADASS NVO Tutorial 4

Simple Image Access Protocol (SIAP)

• Specification for 4 types of image services and archives– CUTOUT service– MOSAIC service– ATLAS archive – POINTED archive

• HTTP Get for rectangular Region of Interest (ROI)– MUST specify in decimal degrees

• POS (ROI center)• SIZE (Angular width)

• Like the Cone Service SIAP returns VOTable• Example

http://cadcwww.hia.nrc.ca/cadcbin/cadcImageQuery.pl?CAT=CNOC1&POS=245.9085,26.540&SIZE=0.05,0.05

October 12, 2003ADASS NVO Tutorial 5

SIAP – continued

• For compliance each service– MUST: perform ROI query and return a URL to image– OPTIONAL: image staging, image retrieval (GetImage)

• Other MUSTs include– FORMAT to indicate desired format of referenced image (e.g.

FITS, JPG, GIF)• http://cxc.harvard.edu/cgi-gen/astrobrowse/bin/

cda/SIAP.pl?POS=194.95,27.967&FORMAT=image/fits&GRADE=TOP&SIZE=0.1

• Metadata accessed with FORMAT=METADATA• Specific UCD fields (see standards doc for complete

listing)– POS_EQ_RA_MAIN, POS_EQ_RA_DEC– VOX:Image_Title, VOX:Image_Naxes …. (where VOX = VO-

Experimental and are non-standard)• Optional Image Generation Parameters (IGP) are permitted

– WCS strongly encouraged for overlay rendering of images• CRPIX, CRVAL, etc.

October 12, 2003ADASS NVO Tutorial 6

SIAP VOTable Example

• Shows image URL embedded in VOTable field

• May contain Multiple image URLs

October 12, 2003ADASS NVO Tutorial 7

Basic Development Steps

• After initial assignment of UCDs to returned parameters and table values…– Code back-end to get data– LOAD data and params into VOTable

• Use existing VOTable tools (e.g. JAVOT)• Do-it-yourself

• Create cgi, web app, or web service and register with prototype registries– Caltech– NCSA– STScI/JHU– More to come

October 12, 2003ADASS NVO Tutorial 8

MAST Cone Search (PHP)

• MAST retrieval of HST instrument data– PHP (server-side scripting

language)– Same code that performs

mission searches used for cone search

• Sample Queryhttp://archive.stsci.edu/hst/search.php?sci_data_set_name=J*&RA=148.88&DEC=69.065&SR=0.05

Contact: Randy Thompson rthomp@stsci.edu

October 12, 2003ADASS NVO Tutorial 9

GALEX Cone Search (.NET)

• Implemented as Web Service (using .NET)

• service development compatible with any standard SOAP client– Unrestricted language

access (JAVA, Perl, e.g.)• .NET provides standard

http get (SDSS cone service)http://skyservice.pha.jhu.edu/devel/ConeSearch/sdssConeSearch.asmx/ConeSearch?ra=180.0&dec=1.0&sr=0.05

Contact: Alberto Conti aconti@stsci.edu

October 12, 2003ADASS NVO Tutorial 10

DSS SIAP (Java Server Page)

• Retrieval of DSS Image References

• Calculates WCS Info• Implemented as JSP• Example URL

http://chart.stsci.edu/gscvo/DSS2.jsp?POS=120.0%2C65.8&FORMAT=image%2Ffits&SIZE=0.05

• Uses Resin Java Servlet Engine with Apache

October 12, 2003ADASS NVO Tutorial 11

Scaling DAL for Science Application

• Galaxy Morphology Demo– one of the first prototypes

using DAL standards– Merging science with new

VO computing technology• Portal integrated DAL

services with preset registry of resources– Accessed Grid

computational Web Service– would be simplified by

implementing VO Registry• mine resource metadata• Standard query support