ProtocolsOverview

Slide1: 

VO Protocols Overview Tom McGlynn NASA/GSFC THE US NATIONAL VIRTUAL OBSERVATORY

Summary: 

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.

Protocol List: 

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)

Formats: 

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, …

Data Access Protocols: 

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

Query languages: 

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

Semantic content: 

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

Services: 

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

Interfaces: 

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

Job Control: 

Job Control Common Execution Environment (CEA) Script/pipeline environment with security and such incorporated (Astrogrid) ROME Handle and schedule tasks that involve remote resources.

DataScope Example: 

DataScope Example View http://heasarc.gsfc.nasa.gov/vo Click on “View 3c273”

Protocols used in DataScope: 

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

Slide13: 

Registry Registry OAI Updates SkyNode SkyNode SkyNode Cone Cone Cone User Cone Cone SIA ADQL SOAP VOTable SSA GET VOTable Archive Images and Image Servers Archive Spectra and Spectra Servers Cone 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