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Registries and metadata-driven searches in a solar-terrestrial grid

context

Rob Bentley (UCL/MSSL)and the EGSO Team

27-29 October 2004, Greenbelt MDVOs in Space and Solar Physics Workshop

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Outline

Overview of EGSOOutline of the query requirementsHow metadata is used within the system

The EGSO catalogues and Registries

Example query

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EGSO – European Grid of Solar Observations

EGSO is a Grid test-bed related to a particular applicationDesigned to improve access to solar data for the solar physics and other communitiesAddresses the generic problem of a distributed heterogeneous data set and a scattered user community

Funded under the Information Society Technologies (IST) thematic priority of the EC’s Fifth Framework Program (FP5)

Started March 2002; duration of 36 months (or so)

Involves 12+ groups in Europe and the US, led by UCL-MSSL

4 in UK, 3 in France, 2+ in Italy, 1 in Switzerland, 2 in USSeveral associate partners, mainly in the US

Objectives include:Building enhanced search capability for solar dataSupport of user community scattered around the worldProvide access to data centres & observatories around the worldWhere possible, provide ability to process data at source

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The Solar Virtual Observatory family

Partners and collaborators provide expertise in solar physics and IT

UK UCL-MSSL & UCL-CS, RAL, University of Bradford

France IAS (Orsay), Obs. de Paris-Meudon, International Space Univ. (Strasbourg)

Italy Istituto Nazionale di Astrofisica, Politecnico di Torino

INAf includes Obs. of Turin, Trieste, Florence and NaplesSwitzerland University of Applied Sciences (Aargau)US SDAC at NASA-GSFC, National Solar

ObservatorySDAC and NSO are also part of the US VSO

Belgium Royal Observatory of BelgiumNetherlands ESA-ESTEC – Solar Group

US VSO: Stanford University, Montana State University

CoSEC:Lockheed-MartinVSPO: LEP at NASA-GSFC (Lab. Extraterrestrial

Physics)

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Accessible Providers

Observatories Archive and Location Access type

Space-based:

SOHO SDAC/GSFC, Greenbelt MD, USAMEDOC/IAS, Orsay, France

HTTPSQL

Yohkoh SDAC/GSFC, Greenbelt MD, USA FTPRHESSI HEDC/ETHZ, Zurich, Switzerland FTPGround-based:

BBSO, KANZ, OACT, YNAO, HSOS

BBSO, Big Bear CA, USA FTP

KPNO, KSAC NSO, Tucson AZ, USA WS (VSO)

Extracted TRACE data available to EGSO through CoSEC; need to improve links to VSO “sourced” datasets (e.g for SHA, HAO/MLSO, etc.)Want to add access to space plasma data through VHO, VSPO, etc.Planning addition of BASS2000 (France), SolarNet (Italy), plus other optical & radio ground-based observatories in Europe and US

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Use of solar observations

The appearance of the Sun changes dramatically with wavelength

Emissions originate from different layers in the atmosphere and different physical phenomena

For a complete picture we need to use as wide a range of observations as possible

Mixture of multi-wavelength observations from space- and ground-based platforms

Identifying observations that match some User search criteria and then retrieving them are major problems

Heliosphere

Corona

Chromosphere-TR

Surface Magnetic Field

Photosphere

2x106 K

8x104 K

6x103 K

31JAN0316JAN03

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Linking into the wider context

Increasing desire to use solar data in study problems that span communities

Space weathero heliosphere,

magnetosphere, ionosphere…

Climate physicsPlanetary physicsAstrophysics

Need to find ways of tying these data togetherSingle data model covering all solar system not practicalIntersecting data models in a general pool should be possible

EGSO trying to achieve interoperability (at some level) with the space plasma community

Main purpose of bringing the VOs together…

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Linking into the wider context

Increasing desire to use solar data in study problems that span communities

Space weathero heliosphere,

magnetosphere, ionosphere…

Climate physicsPlanetary physicsAstrophysics

Need to find ways of tying these data togetherSingle data model covering all solar system not practicalIntersecting data models in a general pool should be possible

EGSO trying to achieve interoperability (at some level) with the space plasma community

Main purpose of bringing the VOs together…

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Generic Query

Identify suitable observations (many serendipitous)Want to access as many different types of data as are available

o Identification should be possible without accessing the datao Existing cataloguing differs in quality, contents, and

dependencieso Data volumes are increasing rapidly - SDO will produce 2 TB/day

User only wants to know if data addressing a problem exists

Locate the dataData scattered, with differing means of access (some proprietary)

o Large and small data providers, with varying resources

Process the dataInvolves extraction and calibration of a subset of raw data

o Often only need a subset of each data seto Uses code defined by instrument teams (SolarSoft, C…)

Return results to the User

Compare results from different instrumentsSolarSoft (IDL) provides a standard platform for analysis

Note exchange in order of 3rd and 4th bullets in the Grid expression of the problem

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The EGSO Search Engine

Enhanced cataloguing describes the data more fullyStandardized versions of observing catalogues (UOC) tie together the heterogeneous data setsSearch Registry is an abstraction of entries in the UOC and allows narrowing of the search in initial stages

New types of catalogue allow searches on events, features and phenomena, not just date & time, pointing, etc…

Solar Event Catalogue (SEC) - derived from published listsSolar Feature Catalogue (SFC) - generated by feature recognition

Ancillary data used to provide additional search criteriaQLK Server provides Phone book access to images, time-series, derived products, etc.; can also do limited processingDSO Server gives Yellow Page information on instruments, etc.Similar hierarchical cataloguing required in other data Grid projects

EGSO is improving the quality and availability of metadata

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Catalogue relationships

Built from

Database of solar observations- instrument - observatory- EGSO available?- observing location- observing interval- description ….

Time coverages- instrument - observing date start- observing date end- observing parameter name- observing parameter value- data source

Solar Observations - date start- date end- wavelengths- coordinates- ….many more relevant characteristics needed for searches

UOC

SR

Event/Feature Catalogs- catalog name- event name- observing date- description ….

SEC/SFC

DSO Built from

Data Archives

Manually Built

QKL

Objective of the improved

metadata, etc. is to be able to

pose questions like:

Identify events when a filament

eruption occurred within 30° of

the north-west limb and there

were good observations in H,

EUV and soft X-rays

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Simplified Architecture

After R. Linsolas, IAS

Architecture defined in terms of three roles:

Consumer, Broker and Provider

ARCHIVES

Consumer Broker

Broker

Provider

Provider

Provider

Cat.

Consumer

GUI

GUI

GUI

EGSO GRID

API

Special Providers

Results

SEC, SFC, UOC,

DSO, QLK, CoSEC

Archive access can be

by FTP, HTTP,

Web Services, cgi-bin…through adaptor modulesBrokers manage

the metadata and decides and

allocates resources

Consumer supports GUI

and API access

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The UOC and Search Registry

Unified Observing Catalogues (UOC)Unified (metadata) form of observing catalogues used to tie together the heterogeneous data, leaving the data unchanged

o Increase interoperability by expressing coordinates in “standard” formats

Self describing, quantized by time and instrument, with no dependencies on ancillary data or proprietary software (and with any errors corrected)Standards defined for future data sets (e.g. STEREO, ILWS, Solar-B)

Search Registry is an abstraction of entries in the UOCRegistry allows the Broker to identify instruments that:

o have data properties matching the search - Static SRo probably have observations during search time interval - Dynamic SR

Reduces need to interact with Data Providers that are unlikely to have data matching the searchStatic Search Registry (sSR) is able to support access to different types of data from solar and heliospheric observations

o Tries to describe instrument capabilities & observing objectives in common way

o Location of observation platform more important as include space plasma data, and for some future solar missions

o First step in search - later steps can be dealt with by other VOso EGSO sSR includes instruments on Ulysses, ACE, Cassini, SDO, STEREO…

The reasoning behind the UOC is universal, allows observations to be described in more interoperable way

Significant similarities in the way we use data means that the static Search Registry can be used to tie solar and heliospheric data together

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Part of the EGSO Data Model

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Contents of the Static Search Registry

Instrument and ObservatoryIncludes space and ground based, solar and heliospheric

Observing DomainWhat trying to observe

o Solar disk, interior, corona, heliosphere, magnetosphere

Observable entityPhotons, particles, fields with sub-divisions

Common termsImager, spectrometer, polarimeter, coronagraphOscillations, waves, H-alpha, composition, irradiance…

Information related to location of observatories and operating interval of the observatories & instruments in separate table

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Finding the data

Data could be located anywhere in the worldUser only needs to know observations exist, not where locatedSystem should isolate the user from the intricacies of access

System should be able to optimize use of sourcesHandling of replicated data and aggregated sources Choice of source - most capable, closest, least used, etc.Must respect any data use policies (proprietary data) and ensure integrity of data providersBurden on data providers minimized to encourage participation

In EGSO, data sources are interfaced by the Provider Role

Information about the data sources is held in the Data Registry - this is managed by the Broker role

o Which instrument data sets are hosted by each data archiveo Which data archives interfaced to each Provider Role

Provider Role uses adaptor modules used to handle different access protocols

o Standardizes way data source interface appears to the system and simplifies addition of new data sources

o Also allows access to data “hosted” by other VOs

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EGSO GUI

GUI supports Event Drive and Date Driven queries

Others being added

Series of portlets allow user to tailor their search depending on the thrust of their query

Wavelengths, Instruments…

Advanced static Search Registry currently being deployed

API will access similar capabilities

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EGSO GUI

GUI supports Event Drive and Date Driven queries

Others being added

Event Drive search returns list of events the used can examine and then selectA list of instruments that made observations is returnedAfter instruments are selected, list of files returned

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EGSO GUI

GUI supports Event Drive and Date Driven queries

Others being added

Event Drive search returns list of events the used can examine and then selectA list of instruments that made observations is returnedAfter instruments are selected, list of files returned

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EGSO GUI

GUI supports Event Drive and Date Driven queries

Others being added

Event Drive search returns list of events the used can examine and then selectA list of instruments that made observations is returnedAfter instruments are selected, list of files returned

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Query Work Flow

User specifies query through the GUI or APIStatic Search Registry narrows the search, based on the criteria specified in the query

Identifies instruments that make the desired type of observationsSearch can includes solar, heliospheric, etc… instruments

Dynamic Search Registry determines (at some granularity) which were actually observing

Includes pointing, observatory location…

User returned list of identified instruments to refine selectionData Registry used to locate archive holding the instrument data and make data requestList of files returned that can be retrieved, used to generate data products, etc.

Convert to processed products if required

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Summary

Although mainly presented EGSO approach, structure allows cross-coupling with other VOsLayered metadata provides several entry points

Commonality with other VOs differ in detail and need

Already exchange of information and resources between the solar VO projects

Approaches of the solar VOs very complementaryNeed to better link into the space plasma, etc. VOs

Main objective of this meeting is to find common ground in the way we describe and handle data to facilitate interoperability

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Useful URLs

General information about EGSO can be found under URL: http://www.egso.orgThe different components of the EGSO system, including the main entry portal, can be accessed from URL:

http://www.egso.org/demo

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So, where are we?

Release 4a of EGSO recently become availablePeople welcome to try this…

Flexible GUI using selectable portlets has been deployed

User able to conduct date driven and event driven searches

o Event driven search accesses EGSO Solar Event CatalogueSystem searches for datasets that match search criteriaUser able to make selections at each stage of the search with aid of supporting data

Search Registry (SR) is still being developedSimplified version currently installed in GUI

o More complex version in preparation (Release 4b)Fully functional Search Registry will allow comprehensive selection of the types of instrument, data, region observed, etc

o Interoperable with the STP & heliospheric observations

Support for refining selection of data for time and spatial coordinates using cursors will be added shortly

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So, where are we? (cont…)

Special Servers are becoming operationalSEC Server is fully integrated into EGSO

o Web Service accessible relational database - SQL in, VOTable outo Several lists are already included: Flares, particle events, CMEs…o Hope to add many more in the future

DSO and SFC Servers functional, but integration not yet complete

o Both available as Web interfaces; Web Service interfaces planned o Over 3 years of data processed for Solar Feature Catalogue

QLK Server is still under development

Processing using CoSEC partially integratedGOES X-ray & energetic particle lightcurves generated for GUIIn process of adding ability to:

o generate quicklook images & movieso extract and process certain datasetso create composite plots for use in searches and publications

Several popular data sources have already been integratedSpace-based: Yohkoh, SOHO & RHESSIGround-based: NSO & Global H-alpha Network (GHAN)Planning to add TRACE & numerous GBO sources in near future