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

VODA - A Sampo Project

Johan Lindroos – CSC Scientific Computing Ltd, Finland

Pekka Järveläinen – CSC Scientific Computing Ltd, Finland

Richard Hook - ESO, Garching, Germanyhttp://www.eso.org/sampo [email protected]

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


High-Level Architecture

Plastic enabled apps.

XML-RPC enabled apps.Local data

AR

VODA – GUI, DB, Application interfaces.


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


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


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 isn’t needed for browsing metadata Handles download for tools which demand local data

(eg, DS9)


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!


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


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







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

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

Documents

voda ivoa victoria

local data ar voda gui

plastic slide

data references

local tools

registry slide

astrogrid ar

vostandards ivoa standards