Download
1 / 17
170 likes | 173 Vues
Learn about the benefits of creating shareable metadata for your repositories, including increased discoverability, more access points for resources, and the ability to combine metadata from different sources. Explore the OAI-PMH protocol for metadata harvesting and how it enables the gathering of metadata from distributed repositories into a combined data store. Discover examples of metadata repositories and the advantages of the OAI approach.
E N D
Various levels of metadata projects Schema A Records Schema B Records Schema C Application Profile Repository
Benefits of creating shareable metadata • It will be interoperable, or meaningful when combined with metadata from other sources. • Your resources are more likely to be found when pooled together with resources from other providers, rather than not being retrieved by searchers due to inconsistencies or gaps in description. • It will increase the number of access points for your resources available to end-users. Source: OAI Best Practices. http://oai-best.comm.nsdl.org/cgi-bin/wiki.pl?PublicTOC
Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) • Protocol A protocol is a set of rules defining communication between systems. • E,g., HTTP, FTP • HarvestingIn the OAI context, harvesting refers specifically to the gathering together of metadata from a number of distributed repositories into a combined data store. http://www.openarchives.org/
Illustration of the repository with OAI-PMH structure Source: Figure 6-4 in Zeng & Qin (2008) Metadata
Two classes of participants: • Data Providers administer systems that support the OAI-PMH as a means of exposing metadata; and • Service Providers use metadata harvested via the OAI-PMH as a basis for building value-added services. • The protocol mandate a common metadata format: unqualified Dublin Core. • http://www.openarchives.org/OAI/2.0/openarchivesprotocol.htm
Before harvesting: each has a different metadata structure e-print FTXT OPAC A&I image
metadata OPAC image FTXT A&I e-print
OPAC image FTXT A&I e-print Author Title Abstract Identifier metadata Metadata from many sources can be gathered together in one database, and services can be provided based on this centrally harvested, or "aggregated" data.
200+ projects: .collections .services.targeted research.pathways.core integration An example: NSDL Metadata Repository Source: NSDL: Core Integration,Technical Overview, 2001
ADLstandard report ADLXMLreport
ADL record merged into NSDL Metadata Repository More Information Title [DOQQ, Digital orthophoto quarter quadrangle], Soda Lake South SW , California. Creator United States Geological Survey Creator Analytical Surveys, Inc. Subject Aerial photographs digital raster; California Subject DOQQ; quad; Band interleaved by line; BIL Description Digital Orthophoto Quarter Quadrangles (black & white) cover the state of California, each quarter quadrangle covering an area 3.75 degrees by 3.75 degrees. Some quadrangles are still in process as of March 2002 Publisher U.S. Geological Survey Western Mapping Center Contributor Alexandria Digital Li brary Date 19970204 Date 19940528 Date 19971030 Type Image Type remote - sensing images Type aerial photographs Format 49189680 bytes Format BIL Format DOQQ Format Digital Orthophotographic Quarter Quadrangle
Benefits of the OAI approach 1. Material can be accessed more widely; 2. Material can be exploited for purposes different from those that originally motivated the creation of the repositories; 3. New and improved services can be constructed because of the possibility of accessing multiple repositories; and 4. There is potential for cost-saving inherent in new models of the scholarly communication process that could be realized through an open archives approach. Summarized by Carpenter (2003)
