OSGeodata

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.

Towards a new geospatial catalog protocol...

For protocol requirements read the OSGeodata Mailing List mentioned above, for requirements of the metadata information model (e.g. for response data) see this OSGeo Wiki page as well as the OSGeodataMetadataModel.

Better name sought:

• Geographic Metadata Harvesting Protocol (sort of OAI-PMH for Geographic Data and Services)
• Geographic Data Discovery Protocol
• Geographic Metadata Dissemination Protocol
• ...?

High level decisions

Search or harvest protocol?

Do we look for a metadata query/search protocol or a metadata harvesting procotol? (metadata harvesting = metadata aggregation and syndication).

Service as own resource or as attribute value to data resource?

There is a dilemma about what constitutes a 'resource' the metadata points to: Is a geographic service, like WMS, a resource on its own? In this case a harvester must subsequently try to request it for more information based on the indicated protocol hopefully indicated by a type value. If the geographic data remains the single source of resource, every file format (like GeoRSS, GML, DXF, Shapefile) as well a service type, like a 'WMS layer' or a 'WFS feature set' needs to be mentioned in the metadata record.

Personal remark: The dilemma get's even stronger if we think of style sheets that render the same geographic data differently. Still, I tend to the latter choice, because all are data streams originating from the single most precious source: geographic data as interpreted, digitized and stored geoinformation) -- Stefan 20:07, 6. Aug 2006 (CEST)

Need for a metadata information model

See OSGeodataInformationModel.

Background

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.

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