[Requests] Comments to candidate OGC GeoSPARQL Standard

Gobe Hobona gobe.hobona at envitia.com
Fri Aug 5 15:08:41 EDT 2011


PART A


1. Evaluator:
      Gobe Hobona
	Envitia Ltd.

2. Submission: 
11-052r3 OGC GeoSPARQL - A Geographic Query Language for RDF Data



PART B


1. Requirement: None.


2. Implementation Specification Section number: Major. Annex C. Section C1

The example implementation of Requirements 18 and 19 shows the encapsulation of GML and WKT literals in CDATA markup.
CDATA markup is ignored by XML parsers. This means that an RDF/XML parser will also ignore the GML and WKT literal in CDATA. Although we, as the geospatial community can implement software to extract the geometries, others in the semantic web community may not be willing to modify their parsers in order to extract this information. Therefore GeoSPARQL should use the standard mechanism built into RDF for handling XML values in properties.

http://www.w3schools.com/xml/xml_cdata.asp

Since the RDF properties geo:asWKT and geo:asGML already specify the geometry encoding, GeoSPARQL could simply use the standard xsd:string datatype for WKT and XMLLiteral for GML. Even if XMLLiteral is difficult for users to read because of the use of UTF8 safe-encoding (< and >), the principle that RDF should be machine-readable across all applications should still be applicable to GeoSPARQL. 

3. Criticality: Editorial

Page 20 has a GML fragment for a Point but with coordinates listed in a posList. 
The GML standard specifies a Point type that uses a pos element and not a posList. 


4. Comments/justifications for changes: None.


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