VODA - A Sampo Project Johan Lindroos – CSC Scientific Computing Ltd, Finland Pekka Järveläinen – CSC Scientific Computing Ltd, Finland Richard Hook - ESO, Garching, Germany

VODA - IVOA Victoria 17 May 2006 Introduction and Motivation Sampo is a collaborative project between Finland and ESO to investigate future data processing requirements and technologies and perform pilot studies A small part of Sampo has been looking at the VO, and specifically the relationship between remote VO resources and local data analysis applications VODA is an experiment to establish a personal, persistent local virtual directory of VO data resources and link this with visualization tools and the VO itself using the Astro Runtime (AR) and Plastic

VODA - IVOA Victoria 17 May 2006 High-Level Architecture Plastic enabled apps. XML-RPC enabled apps.Local data AR VODA – GUI, DB, Application interfaces.

VODA - IVOA Victoria 17 May 2006 Virtual Directory? A local, persistent, private view of the VO Storing references to remote and local data and metadata User may organize these references Visualize (Aladin/TOPCAT/DS9 etc.) User may add new resources to his library from new queries or from external sources An application interface is on the way

VODA - IVOA Victoria 17 May 2006 Data discovery - in a general way... VODA uses the Astrogrid Astro Runtime (AR) for access to VO resources through standard IVOA protocols (Registry, SIAP, SSAP, Cone etc.) Results can be stored in the Virtual Directory, visualized directly by local tools, downloaded, or passed to Plastic-aware applications The Virtual Directory can be updated with search results from any search tool that is Plastic-aware

VODA - IVOA Victoria 17 May 2006 Downloading data References in the Virtual Directory can be downloaded to a local disk when required In future, a download directly into VOSpace could be possible Download isnt needed for browsing metadata Handles download for tools which demand local data (eg, DS9)

VODA - IVOA Victoria 17 May 2006 Why the Astrogrid AR? The Astrogrid Astro Runtime (AR) allows simple access to the Astrogrid Registry and to application and data- services (SIAP, Cone Search etc) AR also offers the possibility of future access to MySpace/VOSpace Use of AR hides future changes of IVOA standards from VODA itself Using the AR is much easier than re-implementing all its facilities from scratch!

VODA - IVOA Victoria 17 May 2006 Experiences with VO-standards IVOA standards allow the construction of a very general tool which makes few assumptions about the data products - as intended! Some problems were encountered when services do not support the specifications fully (eg, some SIAP services do not supply all the expected metadata) We had some problems with the very large number of optional parameters (eg, coverage) in the registry and were unable to rely on these when querying the registry

VODA - IVOA Victoria 17 May 2006 Why Plastic? Experiences... Plastic is EASY and QUICK - only a few days were needed for a basic implementation of a connection with and between Plastic-enabled tools and VODA Any new tools implementing certain messages in Plastic will automatically function with VODA Plastic allows VODA to pass data references to visualization tools and also ingest VOTables from Plastic-enabled tools such as TOPCAT You get a lot for free! Next step is using Plastic-aware versions of tools like AstroScope/DataScope for the discovery phase

VODA - IVOA Victoria 17 May 2006

Conclusions VODA is a simple experimental implementation of the Virtual Directory concept The use of Astro Runtime greatly eases access to multiple VO services The use of Plastic allows very flexible and convenient two-way communication with other (powerful and mature) VO tools The use of these elements, talking standard protocols, means that new VO tools may be quickly and easily developed in a modular way