Data discoveryfrom a

digital library perspective

Greg Janée, Darren HardyUC Santa Barbara

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Outline

• Questions– grappling with granularity– struggling with search– dithering over distribution– pondering process

• Integrating search with access

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Granularity

institution (NASA)

data center (GSFC)

program (MODIS)

product (sea surface temperature)

resolution (1km)

space

time

granule

datum

type

organization

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Approaches I

• ADL– uniform object (metadata) representation– flat list of collections (=containers)– possible extensions:

• collections as first-order objects• nested containers

• THREDDS– hierarchical “collection” datasets– “coherent” datasets (=aggregation server?)– “direct” datasets

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Approaches II

• Granularity on the Web...– webpage– multi-page document– website

• ...and sidestepping it– uniform representation (webpage)– page linking– visible, decomposable identifiers (URLs)

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• Use heuristics to return “best” match

dataset

inheritdescriptive metadata

aggregateintrinsic metadata

Flattening granularity

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Search

• Type– text, numeric, space, time, ...

• Source– data itself– intrinsic metadata– added (usually descriptive) metadata– 3rd party

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Distribution

• Centralized system– eg. Google, ECHO– SPOF; requires resources

• Peer-to-peer– eg. BRICKS, built on P-GRID– MPOF; requires commitment

• ADL: incomplete peer-to-peer

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A “textbook” search process

• Classic process (Lancaster 1979)– Information need– Stated request– Selection of database– Search strategy– Search in database– Screening of output

• Web search - about the same 25 years later

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What’s the real process?• Irrational search (Pharo & Järvelin 2006)

– Textbook search processes insufficient– Disjointed incrementalism theory

• Many smaller steps• Learning during a search• Subjective & dynamic information needs over time

• What’s the ideal for earth science data users?– How do you inform choices during search?– How do you formulate a search, and what’s the

context?– When is enough enough?

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Integrating search with access

• File menu– Open...– Search library...– Close– Quit

• Query results returned as a THREDDS catalog?

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We’re funded to do this!