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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 geographic 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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A protocol specification consists of requests (operations) and responses (information model encoded in a streaming format and error messages, as codes).
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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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* [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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* [http://www.kralidis.ca/blog/2006/08/04/geospatial-catalog-development-brewing/ Blog 3] - geospatial-catalog-development-brewing.
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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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* Paper "Are Geospatial Catalogues Reaching their Goals?" from [http://www.agile2006.hu/papers/Larson_Siliceo_etal.pdf Larson et al.].
  
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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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== Building blocks for metadata management ==
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Building blocks are:
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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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# A geometadata '''management model''' (e.g. internal to each organisation)
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# '''Tools''' to manage the geometadata
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Better name sought (catalogue is probably not the most appropriate noun):
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# A geometadata '''[[OSGeodata metadata exchange model| exchange model]]'''
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# Geographic Metadata Syndication Protocol
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# An '''encoding''' of the geometadata exchange model (probably XML)
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# Geographic Metadata Harvesting Protocol
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# Geometadata '''[[OSGeodata metadata exchange protocol| exchange protocols]]''' (like [[OAI-PMH]], see [[OSGeodata_Discovery]])
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* Other proposals?
 
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** Geographic Data Discovery Protocol
 
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** Geographic Metadata Dissemination Protocol
 
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== Need for a metadata information model ==
 
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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.
 
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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.
 
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See [[OSGeodataMetadataModel]] for further discussion.
 
  
 
== 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»