Metasearch enhanced OGC crawler

HTML list of OGC Services

This light client application offers end users an easy tabular view on the URLs of OGC services collected by the metasearch enhanced crawler since October, 2013 until today. Information as service type, version, server localization, dates of discovery, last verification and current avaialability as well as number of metadata harvested for both service itself and the content it shares. Each column provides a filtering capability, thus it is possible to narrow the final set of services of e.g. WFS type, running in the UK, avaialble after the last check and having metadata already harvested by the catalogue. Each URL may be open in a new browser tab by the doubleclick.

Geocatalogue of metadata of OGC services and related content

Geocatalogue offers an SDI catalogue of metadata collected from OGC services (WMS, WFS, WCS, WPS and SOS) and  the content they operate on (WMS layers, WFS features, WCS coverages, SOS observations). 

Geosparql interface

Metadata harvested from OGC services discovered on Google SE are exposed to the semantic web via a GeoSparwl enpoint implemented using an opensource CSW to RDF middleware application TripleGeoCSW. It runs as a python WSGI service and on the fly transforms SPARQL queries into standard OGC CSW GetRecords requests, receives metadata from remote catalogues in ISO19139 encoding, which transforms to RDF and returns to client who issues the initial query.  

GeoSparql Endpoint for the geocatalogue: http://bolegweb.geof.unizg.hr/ogcwxs/sparql

Examples of (Geo)Sparql requests:

• Discover metadata about geospatial information resources that may contain term "species distribution" in the title:

  PREFIX dc: <http://purl.org/dc/elements/1.1/>
  SELECT *
  WHERE {
  ?s dc:title ?title . 
  FILTER ( REGEX( ?title , "*species distribution*" ))
  }

  SEARCH



• Discover metadata about geospatial information resources thay contain term "species distribution " and the spatial extend is defined by bounding box (Europe in example).

  PREFIX dc: <http://purl.org/dc/elements/1.1/>
  PREFIX geo: <http://www.opengis.net/ont/geosparql#>
  PREFIX geof: <http://www.opengis.net/def/geosparql/function/>
  SELECT *
  WHERE {
  ?s dc:title ?title .
  ?s geo:hasGeometry ?fWKT .
  FILTER ( REGEX(?title , "*species distribution*") && geof:sfWithin(?fWKT, "BOX2D(-5.01 50.23, 1.69 56.12)"^^geo:wktLiteral)) 
  }
  

  SEARCH

Open Data Portal of OGC resources

The fourth component of the Meta-Search Enhanced OGC Crawler is open data portal based on CKAN open source open data platform in order to provide interface to OGC resources to open data community. OGC resources are harvested from CSW APIs deployed for individual OGC Service types and resources they operate on. Based on the individual CSWs, the interface was customized to provide resources (datasets) for individual categories. Open data community user can facilitate the portal to search for OGC resources discovered in the mainstream Web level in standard full search, by browsing categories, collected tags and geospatial bounding box definition.