Transcript Harvesting
Digital Libraries: Harvesting: OpenArchivesInitiative (OAI) I. OAI • aims and concepts • history • organisation II. Harvesting • definitions • data provider and service provider • OAI-PMH OAI: Aims and concepts • increasing the availability of scholarly communication by increasing easier access to digital material • easier access is provided by developing technological frameworks and standards (for example OAI-PMH) • access should be independent of the type of content offered and the economic mechanisems surrounding the content. • OIA is committed to exploring and enabling a new and broader range of application • world-wide consolidation of scholarly archives • free access to the archives (at least: metadata) • consistent interfaces for archives and service provider • low barrier protocol / effortless implementation (e.g., because based on HTTP, XML, DC) History • independent development of different solutions • Santa Fe Meeting 1999 • OAI-PMH= mechanism for harvesting metadata records from one system to another system from a Data Provider to a Service Provider; it‘s not a search protocol, but a base layer on which to build other services Organisation OAI is supported by Digital Library Federation, the Coalition for Network Information and from the National Science Foundation • Steering Committee • Executive Committee • Set of Technical Committees Harvesting: definition Harvesting is the gathering of metadata from a number of distributed repositories into a combined data store Data Provider: deposit and publishing of resources in a repository and expose for harvesting the metadata of resources Service Provider: harvest metadata from Data Provider use metadata for purpose of providing one or more services across all data Multiple service provider can harvest for multiple Data Providers Aggregator is a Data Provider and a Service Provider Harvesting and Searching Harvesting is defined by the OAI-Protocol for Metadata Harvesting (OAI-PMH) • OAI-PMH is based on HTTP • 6 request types =verbs • responses are encoded in XML Flow control Request Types: • Identify •ListMetadataFormats •ListSets •ListIdentifiers •ListRecords •GetRecords example archive.org/oai-script?verb=Identify Response to ListIdentifiers request Response to GetRecord request Example: Data Provider Resumption token • http://www.openarchives.org/ • http://www.oaforum.org/tutorial/