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:
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
Core Model
Dublin Core
ISO19115
FGDC
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.
Others
References
- OWSCat
- Simple Catalog Interface - links to articles, etc
See Also
- http://www.geometa.info/ - German geospatial data search service using dclite4g + OAI-PMH.