- From: RDB2RDF Working Group Issue Tracker <sysbot+tracker@w3.org>
- Date: Fri, 29 Jul 2011 18:23:50 +0000
- To: public-rdb2rdf-wg@w3.org
ISSUE-59 (simple-triples-maps): Syntactic sugar for triples maps that only have a single predicate-object map [R2RML] http://www.w3.org/2001/sw/rdb2rdf/track/issues/59 Raised by: Richard Cyganiak On product: R2RML Currently, a triples map has exactly one subject map, and then a number of predicate-object maps. However, there is a case that we can expect to see reasonably often where a triples map has exactly one predicate-object map. This is when an n:m link table is mapped to a single set of triples. In the interest of making simple things simple and hard things possible, this case could be simplified by removing the intermediate predicate-object map node and just sticking its predicate map(s) and object map directly onto the triples map. This yields a much more readable form. Example: Student(s_id, name) Course(c_id, title) Enrolled(s_id, c_id) Where Enrolled is the many-to-many relationship. The current R2RML mapping would be: <#LinkMap_1_2> rr:logicalTable [ rr:tableName "enrolled" ]; rr:subjectMap [ rr:template "http://data.example.com/student/{s_id}" ]; rr:predicateObjectMap [ rr:predicateMap [ rr:predicate ex:isEnrolled ]; rr:objectMap [ rr:template "http://data.example.com/course/{c_id}" ]; ]. With syntactic sugar, it would become: <#LinkMap_1_2> rr:logicalTable [ rr:tableName "enrolled" ]; rr:subjectMap [ rr:template "http://data.example.com/student/{s_id}" ]; rr:predicateMap [ rr:predicate ex:isEnrolled ]; rr:objectMap [ rr:template "http://data.example.com/course/{c_id}" ]. The spec would say: A triples map MAY have exactly one object map and one or more predicate maps. If these are present, then they form an implicit predicate-object map. This would be a simple change. This has been proposed by Richard here [1] and seconded by Juan here [2]. [1]: http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2011Jul/0169.html [2]: http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2011Jul/0170.html
Received on Friday, 29 July 2011 18:23:51 UTC