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OAI-PMH. The Open Archives Initiative Protocol for Metadata Harvesting. Presenter: Knud Möller Friday, 30.07.2004. Content. Basic idea behind OAI-PMH Architectural Overview Repositories and Harvesters Resources, Items and Records Internal Record Format Sets Selective Harvesting
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OAI-PMH The Open Archives Initiative Protocol for Metadata Harvesting Presenter: Knud Möller Friday, 30.07.2004
Content • Basic idea behind OAI-PMH • Architectural Overview • Repositories and Harvesters • Resources, Items and Records • Internal Record Format • Sets • Selective Harvesting • Response Format • Command Overview OAI-PMH - Knud Möller, DERI Galway
Basic idea behind OAI-PMH • provide a standard protocol for the harvesting/ querying of metadata about any kind of resource - “What kind of resources can you provide and what are their properties?“ • OAI-PMH is only the protocol, needs to be implemented • some implementations exist: • Emblem Project Utrecht http://emblems.let.uu.nl/emblems/html/techoai.html • Virginia Tech (VTOAI) http://www.dlib.vt.edu/projects/OAI/software/vtoai/vtoai.html OAI-PMH - Knud Möller, DERI Galway
Architectural Overview Repositories and Harvesters Harvester Harvester Repository Harvester Harvester OAI-PMH - Knud Möller, DERI Galway
Request Request Request Request Architectural Overview Repositories and Harvesters Harvester Harvester Repository Harvester Harvester Harvesters issue OAI-PMH requests for metadata via HTTP. OAI-PMH - Knud Möller, DERI Galway
Response Response Request Request Request Request Response Response Architectural Overview Repositories and Harvesters Harvester Harvester Repository Harvester Harvester Harvesters issue OAI-PMH requests for metadata via HTTP. A Repository processes the OAI-PMH requests and has to implement the protocol. OAI-PMH - Knud Möller, DERI Galway
Resource Architectural OverviewResources, Items and Records Anything - physical artifact, a digital resource, a concept, etc. Whatever the metadata is about. OAI-PMH - Knud Möller, DERI Galway
Resource Architectural OverviewResources, Items and Records Representation of resource in repository. Can disseminate metadata in various formats. Must always provide Dublin Core. Has unique identifier. Item oai:arXiv.org:cs/0112017 Anything - physical artifact, a digital resource, a concept, etc. Whatever the metadata is about. OAI-PMH - Knud Möller, DERI Galway
Record (lom) Record (oai_dc) Record (id3) Resource Architectural OverviewResources, Items and Records XML-encoded byte stream of actual metadata. Representation of resource in repository. Can disseminate metadata in various formats. Must always provide Dublin Core. Has unique identifier. Item oai:arXiv.org:cs/0112017 Anything - physical artifact, a digital resource, a concept, etc. Whatever the metadata is about. OAI-PMH - Knud Möller, DERI Galway
Internal Record Format I <record> <header> <!-- blabla --> </header> <metadata> <!-- blabla --> </metadata> <about> <!-- blabla --> </about> </record> OAI-PMH - Knud Möller, DERI Galway
Internal Record Format I <record> <header> <!-- blabla --> </header> <metadata> <!-- blabla --> </metadata> <about> <!-- blabla --> </about> </record> <header> <identifier>oai:arXiv.org:cs/0112017</identifier> <datestamp>2002-02-28</datestamp> <setSpec>cs</setSpec> <setSpec>math</setSpec> </header> OAI-PMH - Knud Möller, DERI Galway
Internal Record Format II <metadata> <oai_dc:dc xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance“ xsi:schemaLocation= "http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd"> <dc:title>Using Structural Metadata to Localize Experience of Digital Content</dc:title> <dc:creator>Dushay, Naomi</dc:creator> <dc:subject>Digital Libraries</dc:subject> <dc:description>With the increasing [..bla..] to particular communities of users. </dc:description> <dc:date>2001-12-14</dc:date> <dc:type>e-print</dc:type> <dc:identifier> http://arXiv.org/abs/cs/0112017 </dc:identifier> </oai_dc:dc> </metadata> OAI-PMH - Knud Möller, DERI Galway
Internal Record Format III <about> <provenance xmlns="http://www.openarchives.org/OAI/2.0/provenance" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation= "http://www.openarchives.org/OAI/2.0/provenance http://www.openarchives.org/OAI/2.0/provenance.xsd"> <originDescription harvestDate="2002-02-02T14:10:02Z" altered="true"> <baseURL>http://the.oa.org</baseURL> <identifier>oai:r2.org:klik001</identifier> <datestamp>2002-01-01</datestamp> <metadataNamespace> http://www.openarchives.org/OAI/2.0/oai_dc/ </metadataNamespace> </originDescription> </provenance> </about> OAI-PMH - Knud Möller, DERI Galway
Sets • Items can be organized into sets. • Sets can either be organized flat or hierarchically. OAI-PMH - Knud Möller, DERI Galway
Selective Harvesting • Harvesters can specify some constraints on which items they are interested in • Regarding datestamps: • only items that where created, modified or deleted (optional) in a certain time period • Regarding sets: • only items that belong to a specific set (or any of its subsets) OAI-PMH - Knud Möller, DERI Galway
Response Format <?xml version="1.0" encoding="UTF-8" ?> <OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/“ xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance“ xsi:schemaLocation= "http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"> <responseDate>2002-05-01T19:20:30Z</responseDate> <request verb="GetRecord" identifier="oai:arXiv.org:hep-th/9901001“ metadataPrefix="oai_dc"> http://an.oa.org/OAI-script </request> <GetRecord> <record>...</record> </GetRecord> </OAI-PMH> OAI-PMH - Knud Möller, DERI Galway
Command Overview I • GetRecord: get a specific record, must specify item‘s URI and metadata prefix • Identify: retrieve information about a repository (name, protocol version, supports deletion, ...) • ListRecords: get either all records or a subset, must specify metadata prefix • ListIdentifiers: like ListRecords, but retrieves only headers OAI-PMH - Knud Möller, DERI Galway
Command Overview II • ListMetadataFormats: lists the available metadata formats of a repository • ListSets: returns the set structure of a repository OAI-PMH - Knud Möller, DERI Galway
References • OAI-PMH specification: http://www.openarchives.org/OAI/2.0/openarchivesprotocol.htm OAI-PMH - Knud Möller, DERI Galway
Thanks and goodbye! OAI-PMH - Knud Möller, DERI Galway