Dynamic Targets in YARRRML

Abstract

This extension of [YARRRML] applies the semantics specified by [RML-DYNAMIC-TARGET], an extension of [RML], dynamically defining targets based on source data.

This section is non-normative.

We assume readers have basic familiarity with [RDF], [RML] and [YARRRML] concepts.

In this document, examples assume the following namespace prefix bindings unless otherwise stated:

Prefix	Namespace
`rml:`	http://w3id.org/rml/
`rmle:`	https://w3id.org/imec/rml/ns/extensions#
`htv:`	http://www.w3.org/2011/http#
`ex:`	http://example.org/
`foaf:`	http://xmlns.com/foaf/0.1/

The examples are contained in color-coded boxes. We use the Turtle syntax [Turtle] to write RDF.

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key word MAY in this document is to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

Dynamic targets generate targets based on data of a data source, referred to in this specification as generated targets. Dynamic targets are defined in the targets collections at the root of a [YARRRML] document. To describe a dynamic target, [YARRRML] is extended with following keys for targets:

source: The unique key of a source, defined in the sources collection.
Datatype: string.
id: A template generating identifiers for the generated targets with data of the source of the dynamic target.
Datatype: template.

Every target with the key source is a dynamic target. The value of the other keys of dynamic target are (dynamic) templates instead of (static) strings. These templates MAY contain references to data in the source of the mapping where the dynamic target is used. The mapping exporting its triples to the generated targets, refers to these generated targets by the id of those generated targets. For this purposing, this specification allows templates as values for the targets key within a mapping. The mapping generates the identifiers for those targets using its own data source, which is not necessarily the same data source as source of the dynamic target.

If a mapping and a dynamic target have the same data source, this mapping MAY refer to the generated targets by the unique key of that dynamic target. If a dynamic target is only used in mappings with the same source as this dynamic targets, the key id is optional for this dynamic target.

In the following example the mapping tm_people has the same data source as the dynamic target lt_persons, while the mapping tm_friends has a different data source. The mapping tm_friends can export data to the targets generated by the dynamic target lt_persons, by generating matching identifiers for the generated targets.

sources:
  ls_friends:
    access: friends.csv
    referenceFormulation: csv
  ls_people:
    access: people.csv
    referenceFormulation: csv
targets:
  lt_persons:
    source: ls_people
    id: id_lt_persons_$(regnr)
    type: directhttprequest
    access: "https://pod.playground.solidlab.be/user1/person/$(regnr)"
    referenceFormulation: turtle
mappings:
  tm_people:
    sources: ls_people
    subjects:
      - value: "http://example.org/$(regnr)"
        targets: lt_persons
    predicateobjects:
      - [foaf:name, $(name)]
  tm_friends:
    sources: ls_friends
    subjects:
      - value: "http://example.org/$(registration)"
        targets: id_lt_persons_$(registration)
    predicateobjects:
      - [foaf:nick, $(nickname)]

<#ls_friends> a rml:LogicalSource ; 
  rml:source [
    a rml:RelativePathSource , rml:Source ;
    rml:root rml:MappingDirectory ;
    rml:path "friends.csv" ;
  ] ;
  rml:referenceFormulation rml:CSV ;
.
<#tm_lt_person> a rml:TriplesMap ;
  rml:logicalSource <#ls_friends> ;
  rml:subjectMap [
    a rml:SubjectMap ;
# This is the id template specified as value of the id key in the dynamic target
    rml:template "id_lt_persons_{regnr}" ;
    rml:class rml:LogicalTarget ;
    rml:logicalTarget rmle:ThisMapping ; 
    ] ;
  rml:predicateObjectMap [
    a rml:PredicateObjectMap ;
    rml:predicate rml:target ;
    rml:objectMap [      
      a rml:ObjectMap ;
      rml:template "t_person_{regnr}" ; 
    ] ;
  ] ;
.
<#tm_t_person> a rml:TriplesMap ;
  rml:logicalSource <#ls_friends> ;
  rml:subjectMap [
    rml:template "t_person_{regnr}" ;
    rml:class rml:Target, rmle:DirectHttpRequest ;
    rml:logicalTarget rmle:ThisMapping ; 
  ] ;
  rml:predicateObjectMap [
    a rml:PredicateObjectMap ;
    rml:predicate htv:absoluteURI ;
    rml:objectMap [
      a rml:ObjectMap ;
      rml:template "https://pod.playground.solidlab.be/user1/person/{regnr}" ;
      rml:termType rml:Literal ;
    ] ;
  ] ;
.
<#tm_people> a rml:TriplesMap ;
  rml:logicalSource <#ls_people> ;
  rml:subjectMap [ 
    a rml:SubjectMap ;
    rml:template "http://example.org/{regnr}" ;
    rmle:LogicalTargetMap [
      a rmle:LogicalTargetMap ; 
# The id template specified as value of the id key in the dynamic target, is reused because the target was referenced by its key. 
      rml:template "id_lt_persons_{regnr}" ;
    ] ; 
  ];
  rml:predicateObjectMap [ 
    a rml:PredicateObjectMap ;
    rml:predicate foaf:name ;
    rml:objectMap [ 
      a rml:ObjectMap ;
      rml:reference "name" ;
    ] ;
  ] ;
.
<#tm_friends> a rml:TriplesMap ;
  rml:logicalSource <#ls_friends> ;
  rml:subjectMap [ 
    a rml:SubjectMap ;
    rml:template "http://example.org/{registration}" ;
    rmle:LogicalTargetMap [
      a rmle:LogicalTargetMap ; 
# The id template to refer to the generated targets was specified in the mapping
      rml:template "id_lt_persons_{registration}" ;
    ] ; 
  ];
  rml:predicateObjectMap [ 
    a rml:PredicateObjectMap ;
    rml:predicate foaf:nick ;
    rml:objectMap [ 
      a rml:ObjectMap ;
      rml:reference "nickname" ;
    ] ;
  ] ;
.

In the following example the dynamic target lt_persons doesn't need an explicit id key, because it is only used in mappings with the same data source as the dynamic target.

sources:
  ls_people:
    access: people.csv
    referenceFormulation: csv
targets:
  lt_persons:
    source: ls_people
    type: directhttprequest
    access: "https://pod.playground.solidlab.be/user1/person/$(regnr)"
    referenceFormulation: turtle
mappings:
  tm_people:
    sources: ls_people
    subjects:
      - value: "http://example.org/$(regnr)"
        targets: lt_persons
    predicateobjects:
      - [foaf:name, $(name)]

<#tm_lt_person> a rml:TriplesMap ;
  rml:logicalSource <#ls_friends> ;
  rml:subjectMap [
    a rml:SubjectMap ;
# This identifier is generated by the YARRRML processor (as there is no id specified in the dynamic target)
    rml:template "lt_persons_{regnr}" ; 
    rml:class rml:LogicalTarget ;
    rml:logicalTarget rmle:ThisMapping ; 
    ] ;
  rml:predicateObjectMap [
    a rml:PredicateObjectMap ;
    rml:predicate rml:target ;
    rml:objectMap [      
      a rml:ObjectMap ;
      rml:template "t_person_{regnr}" ; 
    ] ;
  ] ;
.
<#tm_t_person> a rml:TriplesMap ;
  rml:logicalSource <#ls_friends> ;
  rml:subjectMap [
    rml:template "t_person_{regnr}" ;
    rml:class rml:Target, rmle:DirectHttpRequest ;
    rml:logicalTarget rmle:ThisMapping ; 
  ] ;
  rml:predicateObjectMap [
    a rml:PredicateObjectMap ;
    rml:predicate htv:absoluteURI ;
    rml:objectMap [
      a rml:ObjectMap ;
      rml:template "https://pod.playground.solidlab.be/user1/person/{regnr}" ;
      rml:termType rml:Literal ;
    ] ;
  ] ;
.
<#tm_people> a rml:TriplesMap ;
  rml:logicalSource <#ls_people> ;
  rml:subjectMap [ 
    a rml:SubjectMap ;
    rml:template "http://example.org/{regnr}" ;
    rmle:LogicalTargetMap [
      a rmle:LogicalTargetMap ; 
# This identifier template, generated by the YARRRML processor, is reused to refer to the generated targets
      rml:template "lt_persons_{regnr}" ; 
    ] ; 
  ];
  rml:predicateObjectMap [ 
    a rml:PredicateObjectMap ;
    rml:predicate foaf:name ;
    rml:objectMap [ 
      a rml:ObjectMap ;
      rml:reference "name" ;
    ] ;
  ] ;
.

Dynamic Targets in YARRRML

Abstract

1. Overview

1.1 Document conventions

1.2 Conformance

2. Dynamic targets

3. Examples

3.1 Dynamic target with `id` key

3.2 Dynamic target without `id` key

A. References

A.1 Normative references

A.2 Informative references

Dynamic Targets in YARRRML

Abstract

1. Overview

1.1 Document conventions

1.2 Conformance

2. Dynamic targets

3. Examples

3.1 Dynamic target with id key

3.2 Dynamic target without id key

A. References

A.1 Normative references

A.2 Informative references

3.1 Dynamic target with `id` key

3.2 Dynamic target without `id` key