1. September 13, 2004NVO Summer School1 VO Protocols Overview Tom McGlynn NASA/GSFC T HE US N ATIONAL V IRTUAL O BSERVATORY

2. September 13, 2004NVO Summer School2 Summary What are the VO agreements that are used within by VO clients and services? Set the context for building blocks that subsequent talks will describe in detail. Show how the protocols work together.

3. September 13, 2004NVO Summer School3 Protocol List VOTable FITS Cone Search Protocol Simple Image Access (SIA) Protocol Simple Spectral Access (SSA) Protocol SkyNode Astronomical Data Query Language (ADQL) Uniform Column Descriptors (UCDs) Space-Time Coordinates (STC) IVOA Identifiers VO Registry Resource Metadata Registry Access Protocols OAI VOEvent Common Execution Architecture Request-Object Management Environment (ROME)

4. September 13, 2004NVO Summer School4 Formats VOTable –XML format for tabular information Catalog query results List of images or spectra Lists of resources Includes UCDs for columns FITS –Standard astronomical binary data format –Images, spectra, …

5. September 13, 2004NVO Summer School5 Data Access Protocols Cone search –Simple query around a given region –Returns VOTables Simple image access –What images overlap a given region? –Create me an image of this region. –First step produces VOTables with links to image –User downloads images as FITS in second stage Simple spectral access –What spectra are available within this region –More sophisticated than SIA but not fully approved SkyNode –SOAP Web-Service based –Sophisticated access to tables –Supports distributed queries –Uses ADQL –Should eventually subsume Cone-search

6. September 13, 2004NVO Summer School6 Query languages Astonomical Data Query Language (ADQL) –Enhanced version of SQL to support astronomical queries Positional cross-correlations (XMATCH) Complex regions on the sky (REGION) –Both SQL-like and XML representations

7. September 13, 2004NVO Summer School7 Semantic content IVOA identifiers –Scheme for providing unique identifiers for any thing that needs to be distinguished. Services, requests, … –ivo://authority/authority_controlled_string#sub-resource –Used in registries and many other protocols Resource metadata –Standardized format for the description of a service, data collection, facility. –XML format based on the Dublin-core metadata descriptions for published resources. –Used inside registries. Uniform Column/Content Descriptors (UCDs) –Standardized names for table columns with relatively high degree of specificity. –pos.eq.ra or phot.flux;em.ir –Used in VOTables. Space/Time Coordinates –Way of specifying points or regions of space-time. –Can be simple or very complex –Not fully approved

8. September 13, 2004NVO Summer School8 Services Registry –Collection of resources that users can find. –User access via registry access protocol –Registry-registry communication via OAI –Some publishing registries are meant to be seen only by other registries

9. September 13, 2004NVO Summer School9 Interfaces Registry access –How users query the registry –In standards process Open Archive Interface (OAI) –Library community standard –Registry-registry communication to ensure that all registries are up to date. VOEvent –Evolving VO protocol for publishing and receiving notice of transient/urgent events

10. September 13, 2004NVO Summer School10 Job Control Common Execution Environment (CEA) –Script/pipeline environment with security and such incorporated (Astrogrid) ROME –Handle and schedule tasks that involve remote resources.

11. September 13, 2004NVO Summer School11 DataScope Example View –http://heasarc.gsfc.nasa.gov/vohttp://heasarc.gsfc.nasa.gov/vo Click on View 3c273

12. September 13, 2004NVO Summer School12 Protocols used in DataScope VOTable FITS Cone Search Protocol Simple Image Access (SIA) Protocol Simple Spectral Access (SSA) Protocol SkyNode Astronomical Data Query Language (ADQL) VO Registry Resource Metadata Registry Access Protocols OAI Uniform Column Descriptors (UCDs) Space-Time Coordinates (STC) IVOA Identifiers VOEvent Common Execution Architecture Request-Object Management Environment (ROME) Used currently Will be used Could be used

13. Registry OAI Updates SkyNode Cone User Cone SIA ADQL SOAP VOTable SSA GET VOTable Archive Images and Image Servers Archive Spectra and Spectra Servers Cone SSA Cone GET VOTable Registry access Resource Metadata FITS data SQL Databases Data Access Services SIA GET VOTable VOEvent providers Transient events notices Script environment (could be CEA) ROME Script requests Elemental requests and responses