ISSUE-55: Nested predicate-object maps

nested-maps

Nested predicate-object maps

State:

POSTPONED

Product:

R2RML

Raised by:

Richard Cyganiak

Opened on:

2011-07-18

Description:

There is no good reason for R2RML not to allow nesting of predicate-object maps. This seems like an arbitrary restriction.

It makes writing of mappings harder if the tables are denormalized with respect to the target vocabulary.

The cost of supporting nested predicate-object maps in the spec would be negligible. The cost in implementations would be small, because an implementation could easily convert the nested predicate-object maps into an additional “fake” triples map.

Example:

We have a table:
EMPLOYEE (ID, FNAME, STAFFNO, EMPLOYER_ID)

And want a graph of this general structure from each row -- note the target ontology has an explicit class for employment relationships:

[ a biz:EmploymentRelationship;
biz:employee [
a biz:Person;
biz:name ?FNAME;
biz:staffNo ?STAFFNO
];
biz:employer ?EMPLOYER_ID;
]

Here's the mapping:

[] rr:logicalTable [ rr:tableName "EMPLOYEE" ];
rr:subjectMap [ rr:class biz:EmploymentRelationship; rr:column "ID"; ]
rr:predicateObjectMap [
rr:predicateMap [ rr:predicate biz:employee ];
rr:objectMap [ rr:class biz:Person; rr:template "employee/{ID}"; rr:termType "IRI" ];
rr:predicateObjectMap [
rr:predicateMap [[ rr:predicate biz:name ];
rr:objectMap [[ rr:column "FNAME" ];
];
rr:predicateObjectMap [
rr:predicateMap [[ rr:predicate biz:staffNo ];
rr:objectMap [[ rr:column "STAFFNO" ];
];
];
rr:predicateObjectMap [
rr:predicateMap [ rr:predicate biz:employer ];
rr:objectMap [ rr:template "organization/{EMPLOYER_ID}"; rr:termType "IRI" ];
].

Related Actions Items:

No related actions

Related emails:

1. Minutes of 2011-09-06 telecon (from michael.hausenblas@deri.org on 2011-09-06)
2. Re: RDB2RDF WG agenda for 2011-09-06 meeting 1600 UTC (from marcelo.arenas1@gmail.com on 2011-09-06)
3. Re: RDB2RDF WG agenda for 2011-09-06 meeting 1600 UTC (from bvillazon@fi.upm.es on 2011-09-06)
4. Re: RDB2RDF WG agenda for 2011-09-06 meeting 1600 UTC (from juanfederico@gmail.com on 2011-09-06)
5. Re: RDB2RDF WG agenda for 2011-09-06 meeting 1600 UTC (from auer@informatik.uni-leipzig.de on 2011-09-06)
6. RDB2RDF WG agenda for 2011-09-06 meeting 1600 UTC (from michael.hausenblas@deri.org on 2011-09-06)
7. Re: RDB2RDF WG agenda for 2011-08-30 meeting 1600 UTC (from nuno.lopes@deri.org on 2011-08-30)
8. Re: RDB2RDF WG agenda for 2011-08-30 meeting 1600 UTC (from privera.salas@gmail.com on 2011-08-30)
9. Re: RDB2RDF WG agenda for 2011-08-30 meeting 1600 UTC (from marcelo.arenas1@gmail.com on 2011-08-30)
10. Re: RDB2RDF WG agenda for 2011-08-30 meeting 1600 UTC (from juanfederico@gmail.com on 2011-08-29)
11. RDB2RDF WG agenda for 2011-08-30 meeting 1600 UTC (from michael.hausenblas@deri.org on 2011-08-29)
12. Re: Remaining R2RML issues for Last Call (ISSUE-55, ISSUE-57, ISSUE-58) (from michael.hausenblas@deri.org on 2011-08-27)
13. Re: Remaining R2RML issues for Last Call (ISSUE-55, ISSUE-57, ISSUE-58) (from ashok.malhotra@oracle.com on 2011-08-27)
14. Remaining R2RML issues for Last Call (ISSUE-55, ISSUE-57, ISSUE-58) (from richard@cyganiak.de on 2011-08-27)
15. Re: Status of the R2RML document and going last call (from michael.hausenblas@deri.org on 2011-08-02)
16. Status of the R2RML document and going last call (from richard@cyganiak.de on 2011-08-02)
17. Re: RDB2RDF WG agenda for 2011-07-19 meeting 1600 UTC (from juanfederico@gmail.com on 2011-07-19)
18. Re: RDB2RDF WG agenda for 2011-07-19 meeting 1600 UTC (from seema.sundara@oracle.com on 2011-07-19)
19. Re: RDB2RDF WG agenda for 2011-07-19 meeting 1600 UTC (from marcelo.arenas1@gmail.com on 2011-07-19)
20. RDB2RDF WG agenda for 2011-07-19 meeting 1600 UTC (from michael.hausenblas@deri.org on 2011-07-19)
21. ISSUE-55 (nested-maps): Nested predicate-object maps [R2RML] (from sysbot+tracker@w3.org on 2011-07-18)

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