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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.
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== Overview ==
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Proposals like OGC's CSW 2.0 do not fulfill these requirements.
 
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Profiled specifications like WFS or [[OAI-PMH]] (see below) are currently on our short list.
 
  
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These are experimental pages originated from OSGeodata Mailing List on [https://geodata.osgeo.org/servlets/BrowseList?listName=geodata&by=date&paged=false OSGeo.org].
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These are experimental pages ([[OSGeodata Discovery|1]],[[OSGeodata metadata exchange model|2]],[[OSGeodata metadata exchange protocol|3]],[[OAI-PMH|4]]) originated from OSGeodata Mailing List on [https://geodata.osgeo.org/servlets/BrowseList?listName=geodata&by=date&paged=false OSGeo.org].
  
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Let's finally unleash geographic information through open access and dissemination of geographic data and (metadata) search appliances!
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Let's unleash geographic information through open access and dissemination of geographic data and (metadata) search appliances!
  
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:''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)
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Allow to '''[[OSGeodata Discovery| discover geodata]]'''! Let's make metadata 'sexy' again.
  
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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''.
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For the '''[[OSGeodata Discovery| discovery of geodata]]''' we need a
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* '''[[OSGeodataMetadataModel| Geographic metadata exchange model]]''' as well as a
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* '''[[OSGeodataMetadataProtocol| Geographic metadata exchange protocol]]''' (catalog service).  
  
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For '''documentation''' an internal geodata management model is needed. For the '''metadata metadata exchange model''' a proposal was made called  '''[http://wiki.osgeo.org/index.php/Geodata_Metadata_Requirements#Information_model_for_metadata_exchange Dublin Core lite for Geo (DClite4G)]'''.
  
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== Towards a new geospatial catalog protocol... ==
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Remarks: '''Metadata''' is just data about data. There is nothing special regarding its modeling and encoding. Metadata according to metadata exchange model should be strictly free (LGPL?).
  
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For protocol requirements read the OSGeodata Mailing List mentioned above, for requirements of the metadata information model (e.g. for response data) see this [http://wiki.osgeo.org/index.php/Geodata_Metadata_Requirements#Discovery OSGeo Wiki page] as well as the [[OSGeodataMetadataModel]].
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== Pleadings for metadata (models) and adequate protocols ==
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* ''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)
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;Search or harvest protocol?: Do we look for a metadata query/search protocol or a metadata harvesting procotol? See [[OAI-PMH]] for a possible solution.  
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* [http://www.digitalearth.com.au/2006/06/23/lightweight-web-resource-catalogue/ Blog 1] - "Leight Weight Web Resource Catalogue"
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* [http://geotips.blogspot.com/2006/02/more-simple-web-services-catalogues.html Blog 2] - More Simple Web Services Catalogues...", and
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Better name sought:
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* [http://www.kralidis.ca/blog/2006/08/04/geospatial-catalog-development-brewing/ Blog 3] - geospatial-catalog-development-brewing.
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* Geographic Metadata Harvesting Protocol
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* [http://home.badc.rl.ac.uk/lawrence/blog/all Bryan's Blog]: "To extend or not to extend ..." ("In practice, we can exchange any derivative of the ISO19139 profiles using OAI and store them in xml databases.").
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* Geographic Data Discovery Protocol
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* Paper "Are Geospatial Catalogues Reaching their Goals?" from [http://www.agile2006.hu/papers/Larson_Siliceo_etal.pdf Larson et al.].
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* Geographic Metadata Dissemination Protocol
 
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* ...?
 
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== Need for a metadata information model ==
 
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We definitively need a leightweight metadata information model which describes geographic resources being primary data but also filter services.
 
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;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. See [[OSGeodataInformationModel]] for further discussion.
 
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See [[OSGeodataInformationModel]] for more information.
 
  
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== Building blocks for metadata management ==
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Building blocks are:
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# A geometadata '''management model''' (e.g. internal to each organisation)
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# '''Tools''' to manage the geometadata
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# A geometadata '''[[OSGeodata metadata exchange model| exchange model]]'''
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# An '''encoding''' of the geometadata exchange model (probably XML)
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# Geometadata '''[[OSGeodata metadata exchange protocol| exchange protocols]]''' (like [[OAI-PMH]], see [[OSGeodata_Discovery]])
  
 
== Weblinks ==
 
== Weblinks ==
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* [http://wiki.osgeo.org/index.php/Geodata_Metadata_Requirements#Discovery Wiki at osgeo.org] for requirements
 
* [http://wiki.osgeo.org/index.php/Geodata_Metadata_Requirements#Discovery Wiki at osgeo.org] for requirements
 
* [https://geodata.osgeo.org/servlets/BrowseList?listName=geodata Geodata mailing list at osgeo.org] for discussions
 
* [https://geodata.osgeo.org/servlets/BrowseList?listName=geodata Geodata mailing list at osgeo.org] for discussions
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* Pleadings... [http://www.digitalearth.com.au/2006/06/23/lightweight-web-resource-catalogue/ Blog 1] - "Leight Weight Web Resource Catalogue",  [http://geotips.blogspot.com/2006/02/more-simple-web-services-catalogues.html Blog 2] - More Simple Web Services Catalogues...", and [http://www.kralidis.ca/blog/2006/08/04/geospatial-catalog-development-brewing/ Blog 3].
 
  
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Geographic information search services:
 
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* Catalogs:
 
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** [http://www.mapdex.org mapdex.org]
 
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** [http://www.geographynetwork.com ESRI's geography network]
 
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** National Portals: [http://www.geodata.gov US], [http://geodiscover.cgdi.ca CA], [http://eu-geoportal.jrc.it EU], [http://www.gogeo.ac.uk UK], [http://www.geocatalogue.fr FR], [http://www.geoportal.bund.de DE], [http://www.geoland.at AT], [http://www.geocat.ch CH]
 
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* Search engines:
 
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** General: [http://maps.google.com/ Google Maps], MSN live, Yahoo!
 
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** Specialized: [http://www.geometa.info geometa.info] (still german only for linguistic processing reasons)
 
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* GIS with catalog and search components:
 
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** [http://udig.refractions.net uDig], ArcGIS, ...?
 
  
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Specifiations:
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<!-- Kategorien und ev. Koordinaten -->
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* OGC's CSW 2.0
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[[Kategorie: Geodaten]] [[Kategorie: Metadaten]] [[Kategorie: English]]
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* OGC's WFS
 
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* [[OAI-PMH]] - including home, wikipedia, documents, tutorials, tools and demos
 

Aktuelle Version vom 29. Oktober 2006, 12:15 Uhr

Overview

These are experimental pages (1,2,3,4) originated from OSGeodata Mailing List on OSGeo.org.

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

Allow to discover geodata! Let's make metadata 'sexy' again.

For the discovery of geodata we need a

For documentation an internal geodata management model is needed. For the metadata metadata exchange model a proposal was made called Dublin Core lite for Geo (DClite4G).

Remarks: Metadata is just data about data. There is nothing special regarding its modeling and encoding. Metadata according to metadata exchange model should be strictly free (LGPL?).

Pleadings for metadata (models) and adequate protocols

  • 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)
  • Blog 1 - "Leight Weight Web Resource Catalogue"
  • Blog 2 - More Simple Web Services Catalogues...", and
  • Blog 3 - geospatial-catalog-development-brewing.
  • Bryan's Blog: "To extend or not to extend ..." ("In practice, we can exchange any derivative of the ISO19139 profiles using OAI and store them in xml databases.").
  • Paper "Are Geospatial Catalogues Reaching their Goals?" from Larson et al..

Building blocks for metadata management

Building blocks are:

  1. A geometadata management model (e.g. internal to each organisation)
  2. Tools to manage the geometadata
  3. A geometadata exchange model
  4. An encoding of the geometadata exchange model (probably XML)
  5. Geometadata exchange protocols (like OAI-PMH, see OSGeodata_Discovery)

Weblinks

Information:

Von «https://giswiki.hsr.ch/index.php?title=OSGeodata&oldid=3964»