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RIF Simple RDF Mapping Internal Working Draft Editor's Draft 12 July 2010 $Id: Overview.xml,v 1.5 2010/07/13 15:40:39 eric Exp $ http://www.w3.org/2001/sw/rdb2rdf/rifSimpleMapping/ http://www.w3.org/2001/sw/rdb2rdf/rifSimpleMapping/ Eric Prud'hommeaux W3C eric@w3.org Editor Sandro Hawk W3C sandro@w3.org Editor

A subset of RIF can be used to define mappings from constrained graphs to popular patterns. Graphs may be constrained by being a direct expression of a relational database, or data whose schema has evolved. The fragment of RIF described in this document meets many such cases.

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

This is a Editors' Working Draft.

The documents produced by this Working Group are:

  • RDB2RDF Mapping Language (R2RML) Specification
  • RDB2RDF Mapping Language (R2RML) Conformance Tests

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

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Last Modified: $Id: Overview.xml,v 1.5 2010/07/13 15:40:39 eric Exp $

Introduction

Custodians of data are often pushed towards materialization or replications when trying to evolve a data and maintain backward compatibility. Likewise, the creation of Semantic Web views of data, be it a filesystem or a relational database, can create a view different from one that would best serve the community. A light-weight system for defining mappings permits the creation of SemWeb-friendly views, either materialized or virtual. This document defines a subset of RIF capable of mapping transforming s to graph forms which use common schemas like FOAF or DCIM.

Social Data Example (Informative)

Given an graph with people's names and addresses, we with to create a graph which uses the popular vocabularies FOAF and DCIM. This done by creating rule patterns in the existing graph and creating patterns in the desired graph.

Constrained graph:

@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<http://foo.example/DB/People/ID.7#_> <http://foo.example/DB/People#fname> "Bob"^^xsd:string .
<http://foo.example/DB/People/ID.7#_> <http://foo.example/DB/People#addr> <http://foo.example/DB/Addresses/ID.18#_> .
<http://foo.example/DB/People/ID.8#_> <http://foo.example/DB/People#fname> "Sue"^^xsd:string .

<http://foo.example/DB/Addresses/ID.18#_> <http://foo.example/DB/Addresses#city> "Cambridge"^^xsd:string .
<http://foo.example/DB/Addresses/ID.18#_> <http://foo.example/DB/Addresses#state> "MA"^^xsd:string .

The following RIF rules (expressed here in RIF presentation syntax) define a view of the in using the vcard vocabulary:

RIF mapping:

Document(
  Prefix(vcard    <http://www.w3.org/2006/vcard/ns#>)
  Prefix(db_pers  <http://foo.example/DB/People#>)
  Prefix(db_addr  <http://foo.example/DB/Addresses#>)

  Group (
    Forall ?Person ?Name (
        ?Person[vcard:fn->?Name] :- ?Person[db_pers:name->?Name]
    )
    Forall ?Person ?Addr (
	?Person[vcard:adr->?Addr] :- ?Person[db_pers:addr->?Addr]
    )
    Forall ?Addr ?City (
	?Addr[vcard:locality->?City] :- ?Addr[db_addr:city->?City]
    )
    Forall ?Addr ?State (
	?Addr[vcard:region->?State] :- ?Addr[db_addr:state->?State]
    )
  )
)

Presented view:

@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<http://foo.example/DB/People/ID.7#_> <http://www.w3.org/2006/vcard/ns#fn> "Bob"^^xsd:string .
<http://foo.example/DB/People/ID.7#_> <http://www.w3.org/2006/vcard/ns#adr> <http://foo.example/DB/Addresses/ID.18#_> .
<http://foo.example/DB/People/ID.8#_> <http://www.w3.org/2006/vcard/ns#fn> "Sue"^^xsd:string .

<http://foo.example/DB/Addresses/ID.18#_> <http://www.w3.org/2006/vcard/ns#locality> "Cambridge"^^xsd:string .
<http://foo.example/DB/Addresses/ID.18#_> <http://www.w3.org/2006/vcard/ns#region> "MA"^^xsd:string .
Node Transformation Example (Informative)

In addition to changing the graph structure, many use cases demand manipulation of nodes in the graph.

RIF mapping:

Document(
  Prefix(pred <http://www.w3.org/2007/rif-builtin-predicate#>)

  (* this:g1
     this:g1[rdfs:comment->" 

       This ruleset is meant to illustrate the use of RIF for
       rdb2rdf.  In this example, the direct mapping produces
       identifiers like:
            http://foo.example/DB/People/ID.7
	    http://foo.example/DB/Addresses/ID.18
       but we want to convert to identifiers like
            http://bar.example/v01/instances/P6
	    http://bar.example/v01/instances/A17

     " ]
  *)
  Group (
 
    Forall ?Res1 ?Res2 ?Pre1 ?Pre2 ?S1 (
       rename_any(?Res1 ?Res2 ?Pre1 ?Pre2) :- And(
          External(pred:iri-string(?Res1 ?S1))
          External(pred:startswith(?S1 ?Pre1))
          External(pred:iri-string(?Res2 External(func:concat(?Pre2 func:substring(?S1 func:numeric-add(1 func:string-length(func:numeric-add(?Pre1))))))))
       )
    )

    Forall ?Res1 ?Res2 (
       rename(?Res1 ?Res2) :- 
          rename_any(?Pre1 ?Res2 
	             "http://foo.example/DB/People/ID."
	             "http://bar.example/v01/instances/P")
       rename(?Res1 ?Res2) :- 
          rename_any(?Pre1 ?Res2 
	             "http://foo.example/DB/Addresses/ID."
	             "http://bar.example/v01/instances/A")
    )

    (* :main_rule
       :main_rule[rdfs:comment->
         "Every triple using the old URI (in the subject or
          object position) implies a corresponding triple using
          the new URI."]
    *)
    Forall ?X1 ?X2 ?P ?B (
        ?X1[?P->?B] :- And( ?X0[?P->?B] rename(?X0 ?X1) )
        ?B[?P->?X1] :- And( ?B[?P->?X0] rename(?X0 ?X1) )



    )
  )
)

Presented view:

@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<http://bar.example/v01/instances/P.7#_> <http://www.w3.org/2006/vcard/ns#fn> "Bob"^^xsd:string .
<http://bar.example/v01/instances/P.7#_> <http://www.w3.org/2006/vcard/ns#adr> <http://bar.example/v01/instances/A.18#_> .
<http://bar.example/v01/instances/P.8#_> <http://www.w3.org/2006/vcard/ns#fn> "Sue"^^xsd:string .

<http://bar.example/v01/instances/A.18#_> <http://www.w3.org/2006/vcard/ns#locality> "Cambridge"^^xsd:string .
<http://bar.example/v01/instances/A.18#_> <http://www.w3.org/2006/vcard/ns#region> "MA"^^xsd:string .
References SPARQL Query Language for RDF, Eric Prud'hommeaux and Andy Seaborne 2008. SQL.need a better reference here Resource Description Framework (RDF): Concepts and Abstract Syntax, G. Klyne, J. J. Carroll, Editors, W3C Recommendation, 10 February 2004 Reusable Identifiers in the RDB2RDF mapping language, Michael Hausenblas and Themis Palpanas, 2009. RFC3986 - Uniform Resource Identifier (URI): Generic Syntax CVS History 
$Log: Overview.xml,v $
Revision 1.5  2010/07/13 15:40:39  eric
+ social-node-xform

Revision 1.4  2010/07/13 15:35:04  eric
+ presented view

Revision 1.3  2010/07/13 15:26:35  eric
+ example

Revision 1.2  2010/07/13 00:10:45  eric
+ abstract and introduction

Revision 1.1  2010/07/12 23:35:20  eric
CREATED

Revision 1.10  2010/07/12 23:15:42  eric
~ typos revealed when geeking with Sandro

Revision 1.9  2010/06/15 15:23:43  eric
~ validating

Revision 1.8  2010/06/15 14:33:59  eric
~ s/Heading/Header/ per google fight

Revision 1.7  2010/06/15 14:27:08  eric
~ s/∀/∣/g per cygri's comment

Revision 1.6  2010/06/07 15:49:34  eric
+ Extending the Direct Mapping section

Revision 1.5  2010/06/07 14:35:18  eric
+ finished mappings

Revision 1.4  2010/06/03 23:02:58  eric
~ SNAPSHOT

Revision 1.3  2010/06/03 13:06:00  eric
+ start on literal map

Revision 1.2  2010/06/03 12:43:30  eric
~ made algebra all symboly

Revision 1.1  2010/06/02 15:03:34  eric
CREATED