Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/alfa/ealfa/meeting2/talks/IVO_kent_talk.pdf Дата изменения: Sat May 13 00:11:12 2006 Дата индексирования: Sun Dec 23 03:35:22 2007 Кодировка: Поисковые слова: astrophysics

Possibilities for Database Archival and Access
Brian Kent Cornell University

bkent@astro.cornell.edu http://w w w .astro.cornell.edu/~bkent/


Data Archive Objectives
· Platform independent node/server, compatible with standard VO Web Service Protocols · Quick and easy access through the web to data using any web browser with standard plugins · Perform simple analysis and calculations on data on the fly ­ filters, change axes, units · Ability to cross-correlate with other databases, retrieve and compare data · Ability to manually query a database with standard SQL commands · Multiple output formats (ASCII, FITS, binary, GIF, JPEG) for further analysis or display

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VO Web Service Protocols
· The Virtual Observatory is a framework which defines a set of protocols and services for astronomical data use and transfer over networks ­ it is NOT a massive central repository for data. Data representation takes form via XML (eXtensible Markup Language) Data exchange makes use of Web Services using SOAP (Simple Object Access Protocol) and WSDL (Web Service Description Language) Web Services include: ­ Metadata ­ data about the data ... ­ Search algorithms ­ Basic analysis functions (simple plotting, filtering, units, recalibrations, etc.) See Szalay, et al. Microsoft Research Technical Report 2002-85

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Synergy with IVOA
· Importance of bringing the radio part of the spectrum into the VO standards · In the future, cross-correlations will performed on many large surveys, with massive amounts of data (ALFA, SDSS, HST, etc.) · Understanding the tools, standards, and protocols of the VO will allow for integration of ALFA data, giving the community easy access to ALFA data products once data is available
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Exploring the Implementation and Design
Windows DataBase Management System Application Programming Pros MS SQL Server 2000 MySQL MS .NET and C# Well suited for large datasets and easy web implementation Can be expensive Linux PostgreSQL MySQL Java Open source and Free! Sun Java SDK Kit available for free Support is not always easy Can experience slowdown with large datasets Java IDE's are not all free

Cons

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Concept Demonstration
· · · Simple AO data cube of spectra. Each position is assigned an unique index identifier record number Each record contains all the information for that point ­ RA, Dec, Integrated Total Power Measurement, Spectrum, mask, etc. Data reduced in IDL (bandpass calibration), export of IDL structure elements and data to CSV ASCII Import to MySQL, Table Schema Creation Javascript map control HTML Form submission tool PHP -> SQL Query

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Web Prototype Demonstration

Simple application of concepts with MySQL, PHP, CSS, and Javascript

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User clicks on map, activates javascript

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Pixel indices are returned to the form

Submit button queries the database

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Same file is called, but the URL is now different, reflecting the criteria and parameters of the query

PHP returns the results, which are displayed in a query table

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Further Information (handout)
http://www.astro.cornell.edu/~bkent/egg/alfa/
http://www.ivoa.net/ http://www.voservices.org/ · Virtual Observatory · VO Alliance · VO Web Services

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· SkyQuery http://www.skyquery.org/ SQL (Structured Query Language) · MySQL http://www.mysql.com/ · MS SQL Server 2000 http://www.microsoft.com/sql/ · PostgreSQL http://www.postgresql.org/ PHP (Hypertext Preprocessor) · PHP Documentation http://www.php.net/ .NET Development and XML (eXtensible Markup Language) · MS .NET http://www.microsoft.com/net/ · Visual C# http://msdn.microsoft.com/vcsharp/ Java Development · Sun Java SDK http://www.java.com/ Web Services Description, Prototype Applications, and Architecture Szalay, A. et al. 2002, Proceedings of the SPIE, Volume 4846, 124.
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