Alexandria Digital Earth ProtoType Architectural Directions for Distributed Geolibraries Greg Janée [email protected]

Alexandria Digital Earth ProtoType

Architectural Directionsfor

Distributed Geolibraries

Greg Jané[email protected]


2Greg Janée JISC/CNI Stratford-upon-Avon June 14, 2000

Outline

(Previous) testbed design and experiences Vision & goals Architecture: foundation

CRADDL FEDORA

Architecture: additions Standard thesaurus interface Two standard metadata models Core index/search service Tile-based browse/aggregation service Collection discovery service Gazetteer service

Goals, revisited



Testbed: Concepts

a distributed catalog system

Library– set of collections– client (public) services

Collection– set of holdings– metadata reports– library (internal) services

Holding– unique identifier

Holdings have footprints Earth surface location(s)

– point– bounding box– polygon(s)

Gazetteer convertsnames footprints

Services accessible via HTTP Methods = URLs

Metadata encoded in XML Queries Reports



Testbed: Metadata

“Search Buckets”(generic query metadata)

Geographic locations Dates Types Formats Originators Subject-related text

– Assigned terms Identifiers

Reports(descriptive metadata)

Collection

Scan Full Browse Access



Testbed: Services

Clients

Configuration {collection-id} Collection(collection-id) report Query(query) query-id Results(query-id) {holding-id} Metadata(collection-id, holding-id, view) report

Libraries

Collection report Query(query, accumulator) query-thread Metadata(holding-id, view) report

Collections



Testbed: Implementation

webclient intermediary

ADL middleware server

collection driver

web browser

Java + XML

servlet engine JDBC

collection metadata(complete)

HTTP + HTML

renderer(offline)

coverage/statisticsscripts

collection metadata(static)

XML

XML

XML

HTML + GIF

map/footprint service

HTTP server

HTTP + GIF

map server

vectormap data

local file cacheBerkeley/DBM databases(multiple per series)

collection databaseindexed search buckets +basic holding metadata

HTTP servermetadata accessors

(one per series)data accessors

(one per series)

XML

RDBMS

HTTP +XML

HTTP

SRB

to SDSC

collection

middleware

client

Java + XML

configurationscripts



Testbed: CDL Web Client



Testbed: ContentsSeries # Items Size (GB)

Geodex map index 322,000 -

Landsat 1,514,000 -

DOQQ 10,000 600

DRG 1:24,000 3,000 66

DRG 1:100,000 250 6

NASA air photos 502,000 -

MIL air photos 15,000 450

SPOT 200 6

DEM 3,000 1

ADL Gazetteer 4,000,000 -

UCSB AVHRR 15,000 750

TOTAL 6,385,450 1,879



Vision

Fundamental organization of information Self-contained, georeferenced digital objects... ...aggregated into collections... ...networked into libraries The Library constitutes a “Digital Earth”

Static and dynamic content Personal, customizable collections Collaborative use of distributed resources Component-based approach

Specify interfaces and protocols Build representative services


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Greg Janée JISC/CNI Stratford-upon-Avon June 14, 2000

Goals

Find Find appropriate collections Find items within collections

– Using simplified, uniform methods– Using more refined, perhaps collection-specific methods

Assemble, structure, publish Create and populate new collections Structure collections using domain-specific thesauri Make available to others

Use Invoke operations on items Integrate library into user application environment


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CRADDL

D-Lib Magazine, Nov. 1998

client

index/search

naming

repository

update index

submit query;retrieve results

retrieve,deposit, andoperate ondigital objects

resolvename

collection

get configuration,characteristics

updatesummaryinformation


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3.141592.71828

identifier

FEDORA

crop(x,y,w,h)

subsample(factor)

getThumbnail()

type “image”

implementation“image”

apologies to Christophe Blanchi

Type

signature

implementation

attachments

crop(x,y,w,h)subsample(factor)getThumbnail()


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Architecture: additions

Standard thesaurus interface Two standard metadata models

ADL-Basic: supports uniform description & search ADL-Full: supports XML-based querying on entire metadata

Standard index/search services Core index/search service Tile-based browse/aggregation service

Collection metadata Characterizes collection Supports collection discovery

Gazetteer service


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getTopTerms()

getDefinition(term)

getBroaderTerm(term)

etc.

getNarrowerTerms(term)

Standard thesaurus interface

ridgeA long and narrow upland

with steep sides.

physiographic feature

mountain

drumlin

cliff

summit

arête

hogback

broader narrower

related preferred

broader narrower

broader narrower


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ADL-Basic fields & subfields

Originator Subject-related text

Title Assigned terms

Type Format Spatial domain Date

Time period of content Identifier


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FGDC 2.5.1.4DOQ 3.11FGDC 1.1/8.2

Semantics

Source image dateSource DEM dateProduction date

Name

RepeatableOptionalAlways present

CharacteristicsDATEcollectionmetadata

ADL-Basic general structure

FGDC 2.5.1.4DOQ 3.11FGDC 1.1/8.2

Semantics

Source image dateSource DEM dateProduction date

Name

1972-03-051966-01-011982-12-19

ValueDATE

digitalobject

client index/search service


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ADL-Basic field definition

Semantics identifies the nature, genre, meaning, or intellectual content of the item

Content zero or more terms drawn from identified thesauri XML representation <!ELEMENT ...> Collection metadata implications collection metadata

lists all referenced thesauri Query value single term from an identified thesaurus Query operator “is a”

{(“Object Types”, “aerial photograph”), (“Geology Concepts”, “erosion”)}

Type is a (“Object Types”, “image”)

Type


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ADL-Full

Encodes the full, native metadata in a standard syntactic representation RDF ADL’s generic encoding

<source prefix=“MARC”>http://lcweb.loc.gov/marc</source>...<group name="Data quality"> <field name="Accuracy" source="MARC:514g"> <value type="number" unit="meters">25</value> </field> <field name="Contour interval" source="MIL-B:06200a"> <value type="number" unit="meters">10</value> </field></group>


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Index/search services

Core index/search service Based on ADL-Basic Boolean combinations of constraints on ADL-Basic fields and

subfields (only) Support for other, more refined search services

Utilizing ADL-Basic metadata mappings Based on ADL-Full


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Browse/aggregation service

Aggregate statistics Digital objects (scale-dependent) By type, format, and date


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Collection metadata

Static Scope and purpose, maintaining agency, etc.

Derived Referenced thesauri Referenced metadata standards Native ADL-Basic metadata mappings

Statistical summarization via browse/aggregation service


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Stratford-upon-Avon Variant names Stratford upon Avon; Stratford Location N 52° 11’, W 1° 42’ Feature type populated place (NIMA); town (local) Time period 1196–present

805 Feature type U.S. telephone area code

37T Feature type UTM zone

Mississippi Feature type drainage basin

Gazetteer service (1/3)


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postal codes

2nd orderadministrative areas

1st orderadministrative areas


Geographic namespace: spatial partition of a region into uniquely named subregions

countries

time zones

U.S.A.

U.K.

states

counties

ZIP codes

postal codes

national parks

continental plates

California

Louisiana parishes

counties


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map service

client


browse/aggregationservice

gazetteer

placenames

Yogi

Cabbage Patch

Pancake

Bamm-Bamm

Barnacle Bill

Wedge


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Goals, revisited

Find Discovery service based on rich collection metadata Uniform searching based on ADL-Basic More refined searching based on ADL-Basic and ADL-Full Browse/aggregation service

Assemble, structure, publish Uniform use of collections Thesauri and inheritance of collections and digital objects

support customization & structure Collections designed to span gamut big small

Use FEDORA-like extensible digital object model

Documents

Alexandria Digital Earth ProtoType Architectural Directions for Distributed Geolibraries Greg Janée [email protected]