Alexandria Digital Library ADL Metadata Architecture Greg Janée

Alexandria Digital Library 2 Greg Janée / CDL Architecture Working Group / 22-Jan-1999 ADL architecture JIGI Z39.50 Catalog Gazetteer Z39.50 GeoRef GeoWorlds uniform client services middleware collection server API

Alexandria Digital Library 3 Greg Janée / CDL Architecture Working Group / 22-Jan-1999 Middleware services (1/2) o Collection  list –limited form of collection discovery  scan –returns collection metadata, for which ADL has defined a content standard –metadata includes overview information such as spatial & temporal coverages o Search  start –queries are expressed in terms of boolean combinations of “search bucket” constraints –results (holding identifiers) are streamed back  stop

Alexandria Digital Library 4 Greg Janée / CDL Architecture Working Group / 22-Jan-1999 Middleware services (2/2) o Metadata  scan, full, access –each returns a view of the metadata for a holding –the views are optimized for specific purposes: quick evaluation; thorough evaluation; and retrieval  browse –returns information about low-resolution visualizations of the holding, if available o Other functions  access control  evaluation logging  query fan-out & results merge  holding identifier disambiguation

Alexandria Digital Library 5 Greg Janée / CDL Architecture Working Group / 22-Jan-1999 Search buckets o Abstract, searchable indexes o Similar to other “umbrella” metadata schemes such as GILS and Dublin Core, except search buckets are:  optimized for retrieval, as opposed to description  optimized for geospatial searching o Designed to be easy for collections to map to & populate o Open issues  collection-specific buckets?  sub-buckets? o Geographic locations o Dates o Types o Formats o Originators o Assigned terms o Topical text o Identifiers

Alexandria Digital Library 6 Greg Janée / CDL Architecture Working Group / 22-Jan-1999 Metadata reports o All reports are defined by XML DTDs  but level of semantic specification/imposition varies o Scan report  semantics are partially specified  title and selected search bucket values o Full report  semantics are wholly unspecified  only a syntactic structure is imposed: a hierarchical organization of attribute name/value pairs o Access report  semantics are partially specified  enough semantics to support programmatic extraction of online URLs & offline call numbers

Alexandria Digital Library 7 Greg Janée / CDL Architecture Working Group / 22-Jan-1999 Collection development process “raw” data packaged data browse images create, archive & deliver “raw” metadata search buckets scan full access report create (archive) & deliver map, populate & index collection metadata create

Alexandria Digital Library 8 Greg Janée / CDL Architecture Working Group / 22-Jan-1999 ADL collections o ADL Catalog  aerial photographs, scanned & paper maps, GIS layers, scientific datasets, textual documents, videos, etc.  FGDC, USMARC & ad hoc metadata o ADL Gazetteer  place & feature names, earthquake epicenters, volcanic eruptions, etc.  gazetteer-specific metadata o GeoRef  bibliographic records  USMARC metadata o Z39.50 gateway  BIB-1 or GEO attribute sets

Alexandria Digital Library 9 Greg Janée / CDL Architecture Working Group / 22-Jan-1999 Comparison to MoA II o ADL  heterogeneous collections of very heterogeneous items  no (or very weak) metadata model  no object model  no services (that operate on holdings)  direction: services supported by the use of distributed & decentralized service registries and holding-to- service compatibility registries o MoA II  homogeneous collections of somewhat heterogeneous items  uniform metadata model  object model  potentially very rich services  direction: ?