IVOA Standards

1. IVOA Standards • Pedro Osuna • ESA-VO Project • Science Archives and Computer Support Engineering Unit (SRE-OE) • Science Operations Department (SRE-O) • Science and Robotic Exploration Directorate (SRE)

2. The IVOA • In charge of defining Standards for Interoperability • Divided in Working Groups, devoted to different aspects of Scientific and Technical needs for the Virtual Observatory: • Data Access Layer (defines rules on how to access data) • Data Model (defines rules on how to model data) • Registry (defines rules on how to register services) • VOTable (defines rules on how to interchange metadata) • VOQL (defines rules for a common Query Language) • VOEvent (defines rules for transitory event information sharing) • Semantics (defines the meaning of words used within VO) • Grid and Web services (define rules for Grid and Web services use within VO) • Applications (does NOT define rules, but: • [...] “provides a means for VO Applications development and implementation to be closely linked to the standards development in the IVOA” [...] • Applications MAKE USE of the IVOA STANDARDS

3. These were standardized by the International Organization for Standardization (ISO) in 1947 STANDARDS: Are they needed? • An old story: Screw Thread standardisation • [...]”On May 27, 1829,[...]He proceeded to dilate upon the importance of the uniformity of screws. Some may call it an improvement, but it might almost be called a revolution in mechanical engineering[...] Before his time no system had been followed in proportioning the number of threads of screws to their diameter. Every bolt and nut was thus a specialty in itself, and neither possessed nor admitted of any community with its neighbors. To such an extent had this practice been carried that all bolts and their corresponding nuts had to be specially marked, as belonging to each other. Any intermixture that occurred between them lead to endless trouble  and expense, as well as inefficiency and confusion, especially when parts of complex machines had to be taken to pieces for repairs”[...] James Nasmyth.James Nasmyth. Engineer. An Autobiography. Samuel Smiles, editor. New York: Harper and Brothers, 1883 Pages 134-135.

4. Spectra Spectra SSAP Data Models Tables TAP VOEvent Data Access Protocols Lines SLAP Images SIAP Lines Query Language REGISTRY VOTable The IVOA Standards Standards and Processes

5. VOQL, VOTable, VOEvent, Semantics, GWS • [...] The IVOA Query Language group will be in charge of defining a universal Query Language to be used by applications accessing distributed data within the Virtual Observatory framework [...] • [...] VOTable is an XML format defined for the exchange of tabular data in the context of the Virtual Observatory [...] • [...] The objective of the VOEvent effort is to define the content and meaning of a standard information packet for representing, transmitting, archiving, and publishing a discovery of an immediate event in the sky [...] • [...] The Semantics Working Group is concerned with the meaning or the interpretation of words, sentences, or other language forms in the context of astronomy. This includes standard descriptions of astrophysical objects, data types, concepts, events, or of any other phenomena in astronomy [...] • [...] The aim of the GWS WG is to define the use of Grid technologies and web services within the VO context and to investigate, specify, and implement required standards in this area.[...]

6. Registry • [...] The IVOA Registry will allow an astronomer to be able to locate, get details of, and make use of, any resource located anywhere in the IVO space, i.e. in any Virtual Observatory. The IVOA will define the protocols and standards whereby different registry services are able to interoperate and thereby realise this goal [...] Euro VO Registry http://registry.euro-vo.org/search.jsp

7. Data Model • [...] The role of the Data Modeling group is to provide a framework for the description of metadata attached to observed or simulated data. The activity of the Data Model WG activity focuses on logical relationships between these metadata, examines how an astronomer wants to retrieve, process and interpret astronomical data, and provides an architecture to handle them. What is defined in this WG can then be re-used in the protocols defined by the DAL WG or in VO aware applications [...]

8. Data Access Layer • [...] The task of the DAL working group is to define and formulate VO standards for remote data access [...] • Simple Image Access Protocol SIAP • Defines rules to access Astronomical Images • Simple Spectrum Access Protocol SSAP • Defines rules to access Astronomical Spectra • Simple Line Access Protocol SLAP • Defines rules to access Atomic and Molecular Spectral Lines • Table Access Protocol TAP • Defines rules to access Astronomical Catalogues information

9. Standards for this workshop

10. Specifications DATA ACCESS • Simple Image Access Protocol • http://ivoa.net/Documents/latest/SIA.html • Simple Spectrum Access Protocol • http://ivoa.net/Documents/latest/SSA.html • Table Access Protocol (draft) • http://ivoa.net/Documents/latest/TAP.html DATA MODELS • Spectrum Data Model • http://ivoa.net/Documents/latest/SpectrumDM.html

11. IMAGES SIAP LINES SLAP TABLES TAP SPECTRA SSAP Data Access Layer DAL Data Access Protocols and the applications that use them