OLACA: the OLAC Aggregator

OLACA is an aggregator that harvests the complete set of metadata records from all participating archives of the Open Language Archives Community and serves them back through a single data provider that is compatible with the metadata harvesting protocols of both the Open Archives Initiative and OLAC. In addition to the basic aggregation service, OLACA also provicdes:

• Selective querying through the use of the Query verb (see A query facility for selective harvesting of OLAC metadata).
• Formatting of OLAC coded values to display labels through use of the olac_display metadata format and conversion of OLAC records to equivalent Simple Dublin Core records through use of the oai_dc metadata format (see Specifications for an OLAC metadata display format and an OLAC-to-OAI_DC crosswalk).

OAI interface documentation

Repository identifier: OLACA.language-archives.com
OAI protocol version: 2.0
OLAC protocol version: 1.0
BASE-URL: http://www.language-archives.org/cgi-bin/olaca3.pl

Verbs

For arguments (O) indicates optional, (M) indicates mandatory, and (E) indicates exclusive (ie. that parameter and no others may be specified, otherwise that parameter may not be specified).

• verb=Document
  test: verb=Document

• verb=GetRecord
  arguments=identifier(M), metadataPrefix(M)
  test: verb=GetRecord&identifier=oai:ethnologue.com:aaa&metadataPrefix=oai_dc
  test: verb=GetRecord&identifier=oai:ethnologue.com:aaa&metadataPrefix=olac
  test: verb=GetRecord&identifier=oai:ethnologue.com:aaa&metadataPrefix=olac_display

• verb=Identify
  test: verb=Identify

• verb=ListIdentifiers
  arguments=metadataPrefix(M), until(O), from(O), set(O), resumptionToken(E)
  test: verb=ListIdentifiers&metadataPrefix=oai_dc
  test: verb=ListIdentifiers&metadataPrefix=olac
  test: verb=ListIdentifiers&metadataPrefix=olac_display
  test: verb=ListIdentifiers&metadataPrefix=olac&from=2005-01-01
  test: verb=ListIdentifiers&metadataPrefix=olac&until=2006-01-01
  test: verb=ListIdentifiers&metadataPrefix=olac&from=2005-01-01&until=2006-01-01

• verb=ListMetadataFormats
  arguments=identifier(O)
  test: verb=ListMetadataFormats
  test: verb=ListMetadataFormats&identifier=oai:ethnologue.com:aaa

• verb=ListRecords
  arguments=metadataPrefix(M), until(O), from(O), set(O), resumptionToken(E)
  test: verb=ListRecords&metadataPrefix=oai_dc
  test: verb=ListRecords&metadataPrefix=olac
  test: verb=ListRecords&metadataPrefix=olac_display

• verb=ListSets
  test: verb=ListSets

• verb=Query
  test: verb=Query&elements=0&sql=OaiIdentifier+like+'oai:www.ldc.upenn.edu:%25' (all records from LDC)
  test: verb=Query&elements=2&sql=e1.Content%3D'text/xml'+and+e2.tagName%3D'language'+and+e2.Code%3D'fra' (all French language resources in XML)

Metadata formats

In this implementation the following three formats are available for all records.

• prefix=olac
  schema=http://www.language-archives.org/OLAC/1.1/olac.xsd
• prefix=olac_display
  schema=http://www.language-archives.org/OLAC/1.1/olac.xsd
• prefix=oai_dc
  schema=http://www.openarchives.org/OAI/2.0/oai_dc.xsd

See output from verb=ListMetadataFormats.
 

Error conditions

The following links test the error conditions reported by this repository:

• error=badArgument
  test: verb=GetRecord&identifier=oai:ethnologue.com:aaa
  test: verb=GetRecord&metadataPrefix=oai_dc
  test: verb=ListIdentifiers
  test: verb=ListIdentifiers&resumptionToken=part2&metadataPrefix=oai_dc
  test: verb=ListRecords
  test: verb=ListIdentifiers&metadataPrefix=olac&from=2003/01/01
  test: verb=ListIdentifiers&metadataPrefix=olac&from=2002-12-1
  test: verb=ListIdentifiers&metadataPrefix=olac&until=2004-jan-01
  test: verb=Query

• error=badResumptionToken
  test: verb=ListIdentifiers&resumptionToken=X32
  test: verb=ListRecords&resumptionToken=X32
  test: verb=ListRecords&resumptionToken=Xolac

• error=badVerb
  test: verb=Sort

• error=cannotDisseminateFormat
  test: verb=GetRecord&identifier=oai:ethnologue.com:aaa&metadataPrefix=marc
  test: verb=ListIdentifiers&metadataPrefix=marc
  test: verb=ListRecords&metadataPrefix=marc

• error=idDoesNotExist
  test: verb=GetRecord&identifier=oai:ethnologue:AAA&metadataPrefix=oai_dc
  test: verb=GetRecord&identifier=oai:ethnologue.com:ABCD&metadataPrefix=oai_dc
  test: verb=ListMetadataFormats&identifier=oai:ethnologue.com:ab
  test: verb=ListMetadataFormats&identifier=oai:ethnologue.com:abcd

• error=noRecordsMatch
  test: verb=Query&elements=2&sql=e1.Content%3D'text/xml'+and+e2.tagName%3D'language'+and+e2.Code%3D'aaa'
  test: verb=ListIdentifiers&metadataPrefix=olac&from=2003-01-01&until=2002-01-01

• error=noMetadataFormats
  Not applicable, since every valid identifier may return any of the three metadata formats.

• error=noSetHierarchy
  test: verb=ListSets
  test: verb=ListIdentifiers&set=Languages