DCLite4G

DCLite4G is an effort to

• establish a common information model with mappings to well known formats for geospatial metadata
• provide a vocabulary/recommendations for spatial extensions to Dublin Core
• support simple interfaces for collecting and querying geospatial metadata

Getting involved

Mailing List

Feel welcome to join the discussion and development mailing list:

• http://lists.eogeo.org/mailman/listinfo/dclite4g

TODO

• extract more of the specifics from Geodata Metadata Requirements. (This has changed a lot from the original version in the history & current version which has data sets differentiated from data sources, which may be files or databases or services)
• update docs on Geodata Metadata Model
• draw some UML to appease people?

Information Model

References

• Dublin Core lite for Geo
• OGC Catalog Services 2 Specification 6.3.3, Core returnable properties
• OGC ebRIM profile of CSW specification, Appendix B.5, Table B.3 - Slots defined in the Basic package
• iGeoResourceInfo class in uDig
• GeodataCommons Metadata Whitepaper

Query Interface

OAI-PMH

The Harvesting Protocol (version 2.0) specification together with Implementation Guidelines

Following are specific guidelines for a minimal OAI-PMH implementation of a so called 'data provider' using only the mandatory 'unqualified' Dublin Core (DC):

• Only three operations (verbs) are needed: Identify, ListMetadataFormats and ListRecords.
• Following operations are not required (initially): ListIdentifiers, ListSets, GetRecord.
• No incremental harvesting (resumption process for ListXxx operations with more than 1000 records)
• No compression as defined in the OAI-PMH spec. (compression at lower http level still possible)
• Date granularity may be 'day' not seconds (YYYY-MM-DD)
• Keeping track of deleted record may not be supported (deletedRecord=no)
• Mandatory DC supported as data model is sufficient for a start but with specific semantics (e.g. coverage, relation) (see also example below):
  • dc:description contains dct:abstract
  • dc:coverage contains bounding box encoding as defined in http://georss.org/simple.html#Box
  • dc:date means in fact dct:modified
  • dc:relation is filled in with dclite4g:onLineSrc. If dc:type='service' dct:hasPart can be derived from GetCapabilities.

Additional bounding box query property for ListRecords.

References

• OWSCat
• Simple Catalog Interface - links to articles, etc

See Also

• http://www.geometa.info/ - German geospatial data search service using dclite4g + OAI-PMH.