Working with Data Providers in a Distributed Data Environment

Raymond J. WalkerTodd A. KingSteven P. Joy

Lee F. BargatzePeter Chi

James WeygandRobert L. McPherron

Presented at Virtual Observatories in GeoscienceDenver, Colorado

June 12, 2007

New Challenges

Background• Most Heliophysics data are available through

independent repositories.– Found around the world– Use different metadata standards – Are organized differently

• The Heliophysics Virtual Observatories have been tasked with connecting these disparate repositories into a logical whole that enables scientists to locate and access the data and services they need.

The VMO Approach: Part I

• Selected the Space Physics Archive Search and Extract (SPASE) metadata standard and its XML representation to describe resources.

• Enables interoperability in a federated environment.

– Acts as an “interlingua” or intermediate language through which the VMO communicates with data repositories.

– Common metadata allows the repositories to be interconnected.

• Current state of SPASE– Version 1.2.0 has been released and VMO has baselined to that

version.– Defined a standard data model for all of Heliophysics.

The Elements

• Resource descriptions are stored in registries.

• The VMO provides services:– Query registries– Aggregate and organize the

responses– Direct users to the resource– Provide data services

(reformat, manipulate, display, and analyze)

Resource

Repository

Registry

Access pointModel and Methods

Organized in a Self-declared Network

VMO

VxOResidentArchive

IndividualResearcher

The Approach: Part II

• Generate resource descriptions in SPASE XML.

• The SPASE data dictionary is scientifically very rich. • SPASE is so rich that the learning curve is steep.

• At best it is a formidable task to populate the registries.

• Most data providers do not have the resources to create the SPASE metadata and populate the registries.

• Develop a system for creating and populating the metadata with minimum effort.

Creating SPASE Metadata

• Built tools to edit and verify the SPASE metadata.

• Built tools to populate the registries.

• Enlisted a group of domain experts (X-men) to work with data providers.

Qualifications of the Magnetospheric X-men

• Research scientists who are actively engaged in the analysis of magnetospheric data.– Must understand space plasma physics.– Must understand space particles and fields instruments or have sufficient

background that they can quickly learn about them.– Must be expert in time series data analysis techniques.

• X-men must augment their scientific background with training in the principles of data management.

• Must understand the details of the SPASE data model.

• Must be expert in tools used for creating the metadata and populating the registries.

What X-men do

• Develop a plan to make all of the data useful for magnetospheric research available to the community.– We are working to make the list exhaustive.– The list includes correlative data which we plan to access

through the other VXOs.

• Prioritized the ingestion tasks and work out an ingestion schedule.

• Contact data providers and jointly work out a plan to include their data in the VMO.

• The SPASE data model is complex.

• The X-men have identified structure in the model that can be used to build tools to aid in writing the high level metadata.

SPASE Editors Developed by VMO(Web Based)

SPASE Editors Developed by VMO(Excel and Matlab)

(Input by VMO members or data providers)

Programmed by VMO

SPASE Model

1) Ontology Tree 2) Enumeration Lists 3) Custom Settings

spase_model

WDC Geomagnetic Master Catalog

1) Acknowledgement File 2) Data Granule Existence Map 3) Granule Path, Name, Specifics

wdc_1_min

XML Files

create_spase_structurepopulate_structurewrite_structure

Version 1.2

SPASE Editors Developed by VMO(IDL)

Why Not Just One Editor?• Each of the three X-men uses a different SPASE editing scheme.

• The SPASE leaning curve is sufficiently steep that they didn’t want to learn a new software system.

• The three tools use approaches with which they are comfortable.

• The existence of these three approaches plus others developed by the SPASE consortium hopefully will allow data providers to select software with which they are comfortable.

• For a first hand discussion see Bargatze et al., (this meeting)

Automating the Generation of Detailed SPASE XML

Validation Tool

SPASE Data Dictionary Tool

Registry Tools

Working with Data Providers to make Data Available Through VMO

The X-men assist the data providers to:• Use a SPASE editor to write high level SPASE XML.

• Verify the XML.

• Create Rule Sets (or other software) to populate the detailed level SPASE XML.

• Establish the registry at the remote site, if desired.

• Load the high level SPASE XML into the registry.

• Run the Rule Sets (or other software) to populate the registry.

Most importantly an expert is available to data providers at each step of the process.