OSGeodata: Unterschied zwischen den Versionen

Version vom 21. August 2006, 09:46 Uhr

These pages are about our search of "a protocol for the incremental exchange of metadata about geographic resources between systems" which is open, lean and mean. Proposals like OGC's CSW 2.0 do not fulfill these requirements. Profiled specifications like WFS or OAI-PMH (see below) are currently on our short list.

These are experimental pages originated from OSGeodata Mailing List on OSGeo.org.

Let's finally unleash geographic information through open access and dissemination of geographic data and (metadata) search appliances!

Managing metadata well is the key to making a repository of open geographic data really useful and re-usable. Creating metadata can be a dull chore. Part of the problem is over-focus on production, rather than consumption; on standards, rather than on usage. The Geodata Committee at OSGeo has been working on a "simplest useful thing" approach to geographic metadata.... (Citation from Jo Walsh)

Keywords: Open access to and dissemination of geographic data (geodata) and information; Metadata; Finding, harvesting or discovery of geodata and web map services; Interoperability; Integration; Service binding; Spatial data infrastructure; Standards.

Towards a new geographic catalog protocol...

A protocol specification consists of requests (operations) and responses (information model encoded in a streaming format and error messages, as codes).

For protocol requirements read OSGeodataMetadataProtocol.

For proposals around the metadata information model see

• OSGeodataMetadataModel
• and Geodata metadata requirements at OSGeo Wiki
• IESR's Extension to OAI-PMH Dublin Core

Need for a metadata information model

The currently proposed ISO 19115 spec. has mainly two weaknesses: It is too complex (even the core) and it does not cover service description. Extending an already heavyweight spec. probably does'nt make it more lightweight.

We definitively need a metadata information model. a metadata model is nothing else than a usual information model. Information models are the basis for capturing data, database management as well as for data exchange protocols. This metadata information model should be lightweight and should describe geographic resources being primary data but also filter services.

See OSGeodataMetadataModel for further discussion.

Weblinks

Information:

• Wiki at osgeo.org for requirements
• Geodata mailing list at osgeo.org for discussions
• Pleadings... Blog 1 - "Leight Weight Web Resource Catalogue", Blog 2 - More Simple Web Services Catalogues...", and Blog 3.

Geographic information search services:

• Catalogs:
  • mapdex.org
  • ESRI's geography network
  • National Portals: US, CA, EU, UK, FR, DE, AT, CH
• Search engines:
  • General: Google Maps, MSN live, Yahoo!
  • Specialized: geometa.info (still german only for linguistic processing reasons)
• GIS with catalog and search components:
  • uDig, ArcGIS, ...?

Specifiations:

• OGC's CSW 2.0
• OGC's WFS
• OAI-PMH - including home, wikipedia, documents, tutorials, tools and demos