Alexandria Digital Earth ProtoType The ADEPT Digital Library Architecture JAMES FREW GREG JAN E Alexandria Digital Library Project University of California Santa Barbara Alexandria Digital Earth ProtoType ADEPT Introduction Alexandria Digital Earth ProtoType ADEPT is Distributed digital library for geo referenced information Services supporting DL federation and interoperation Large geospatial collections Goal an Internet library layer Organization Persistence Accessibility Scalability Lots of collections Big collections small collections Heterogeneous contents Frew Cornell DL seminar 2002 04 23 2 Alexandria Digital Earth ProtoType Outline Core library architecture Metadata interoperability Other features Query translation Collection discovery Frew Cornell DL seminar 2002 04 23 3 Alexandria Digital Earth ProtoType ADEPT Core Library Architecture Alexandria Digital Earth ProtoType Architectural Elements Item structured descriptions reports contents optional Library set of collections client public services Collection set of items library internal services a distributed catalog system Frew Cornell DL seminar 2002 04 23 5 Alexandria Digital Earth ProtoType The Big Picture client library middleware server proxy collection ADEPT collection library middleware server collection item item item Frew Cornell DL seminar 2002 04 23 item 6 Alexandria Digital Earth ProtoType Role of the Middleware logical view client collection discovery service middleware RDBMS Z39 50 collection item collection item item local thesaurus vocabulary Frew Cornell DL seminar 2002 04 23 local access point standard services access control thin client support distributed search brokering of queries results proxying of collections items creation organization of local collections functional view 7 Alexandria Digital Earth ProtoType Middleware Interfaces 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 Frew Cornell DL seminar 2002 04 23 8 Alexandria Digital Earth ProtoType Metadata Reports Collection Metadata that applies to entire collection Bucket Item s bucket metadata Scan Brief 1 line subset of bucket report Full All the item s metadata in whatever format Browse URL s reduced resolution graphics Access URL s content if available Frew Cornell DL seminar 2002 04 23 9 Alexandria Digital Earth ProtoType A Complete System The Boxology C L I E N T M I D D L E W A R E S E R V E R web browser HTTP SDLIP proxy other clients OR HTTP web intermediary XML HTML converter HTTP transport RMI transport XML client side services Java classes access control mechanisms core functionality access control service and collection level query fan out results merging query result ranking result set caching ranking methods configuration file server side interface Java interfaces XML JDBC RDBMS generic DB driver query translator thesauri paradigm library proxy driver Z39 50 driver configuration files Python scripts Frew Cornell DL seminar 2002 04 23 group driver 10 Alexandria Digital Earth ProtoType Metadata Interoperability Alexandria Digital Earth ProtoType ADEPT s Interoperability Problem Distributed heterogeneous collections locally autonomously created and managed Minimize impact on collection providers allow use of native metadata Uniform client services common high level interface across collections discover and exploit collection specific interfaces Assumptions items have metadata items have sufficient good metadata i e this is a metadata interoperability problem Frew Cornell DL seminar 2002 04 23 12 Alexandria Digital Earth ProtoType Bucket Concept Abstract metadata category Strongly typed Well defined search semantics query terms query operators Explicitly mapped from source metadata FGDC 1 3 Time period of content 2001 09 08 Bucket level search uniform across all collections e g search all collections for items whose Originator bucket contains the phrase geological survey Frew Cornell DL seminar 2002 04 23 13 Alexandria Digital Earth ProtoType Bucket Properties name Coverage date semantic definition The time period to which the item is relevant data type strictly observed calendar date or range of calendar dates syntactic representation strictly observed ISO 8601 Frew Cornell DL seminar 2002 04 23 14 Alexandria Digital Earth ProtoType What is a bucket 2 2 Source metadata is mapped to buckets buckets hold not just simple values 2001 09 08 but rather explicit representations of mappings FGDC 1 3 Time period of content 2001 09 08 may have multiple values per bucket Bucket definition includes search semantics query terms ISO 8601 date range query operators contains overlaps is contained in Some semantics are fuzzy to accommodate multiple implementations Frew Cornell DL seminar 2002 04 23 15 Alexandria Digital Earth ProtoType Collection level aggregation Collection level metadata describes buckets supported by the collection item level metadata mappings statistical overviews item counts spatiotemporal coverage histograms Example de XML ized in collection foo the Originator bucket is supported and the following item fields are mapped to it FGDC 1 1 8 1 Citation Originator 973 items USGS DOQ PRODUCER Producer 973 items DC Creator Creator 1249 items unknown 6 items Frew Cornell DL seminar 2002 04 23 16 Alexandria Digital Earth ProtoType Searching collections Bucket level uniform across all collections example search all collections for items whose Originator bucket contains the phrase geological survey Field level collection specific but discovery and invocation mechanisms are uniform functionally equivalent to searching the entire bucket plus additional constraint example search collection foo for items whose FGDC 1 1 8 1 field within the Originator bucket contains the phrase Frew Cornell DL seminar 2002 04 23 17 Alexandria Digital Earth ProtoType Bucket types 1 7 6 bucket types spatial temporal hierarchical textual qualified textual numeric Type captures the portion of the bucket definition that has functional implications data type syntactic representation query terms query operators Complete bucket definition name semantic definition bucket type Frew Cornell DL seminar 2002 04 23 18 Alexandria Digital Earth ProtoType Bucket types 2 7 Spatial data type any of several types of geometric regions defined in WGS84