This document discusses generating high quality linked data from heterogeneous data sources. It describes how linked data is derived from different data structures and formats and needs to be consistent. It presents challenges in linked data generation including data and semantic heterogeneity. It proposes using the RML mapping language to reduce heterogeneity and facilitate uniform linked data generation. The RML mapper tool is presented for executing RML rules to generate linked data.

1. High Quality
Linked Data Generation
Dr Anastasia Dimou
Post-Doc researcher
imec.be - IDLab.technology
Anastasia.Dimou@imec.be
@natadimou

2. High Quality
Linked Data Generation
from Heterogeneous Data
best practices for semantically annotating &
connecting structured data on the (Semantic) Web

3. High Quality
Linked Data Generation
from Heterogeneous Data
Linked Data is (still) not intuitively available on the Web

4. High Quality
Linked Data Generation
from Heterogeneous Data
Linked Data is derived from heterogeneous
data sources, structures & formats

5. High Quality
Linked Data Generation
from Heterogeneous Data
Linked Data needs to be consistent

6. Human agents do not want to
put in effort to provide Linked Data
until there are software agents that use it

7. Why is Linked Data Generation
Such a difficult task?

8. data owner
custom implementation
Linked
Data
my
data

9. data owner
custom implementation
Linked
Data
my
data

10. data owner
Linked
Data
Linked
Data
Linked
Data
Linked
Data
XMLCSV JSONDB
format-specific implementation

11. data owner
Linked
Data
Linked
Data
Linked
Data
Linked
Data
XMLCSV JSONDB
Linked
Data

12. facilitate Linked Data generation by
reducing data & semantic heterogeneity
& increasing Linked Data quality

13. data owner
Linked
Data
Linked
Data
Linked
Data
Linked
Data
DB CSV XML JSON
multiple data sources

14. data owner
DB CSV XML JSON
uniform execution
Linked
Data

15. data owner
DB CSV XML JSON
?
uniform declaration
Linked
Data

16. data owner
DB CSV XML JSON
?
uniform declaration
Linked
Data

17. declaration
execution
assessment

18. data owner
DB CSV XML JSON
Linked
Data
?

19. data owner
DB CSV XML JSON
R2RML
Linked
Data
Linked
Data

20. data owner
DB CSV XML JSON
R2RML
Linked
Data
Linked
Data
Extending R2RML to a source-independent mapping language for RDF
A. Dimou et al.

21. data owner
DB CSV XML JSON
R2RML
Linked
Data

22. http://RML.io
RML: A Generic Language for Integrated RDF Mappings
of Heterogeneous Data. A. Dimou et al.

23. bibo:Document
bibo:presentedAt<http://ex.com/paper/{id}>
id title venue
1 Assessing & Refining Mappings to RDF to improve Dataset Quality ISWC 2015
2 RMLEditor : a graph-based editor for Linked Data mappings ESWC 2016
3 An ontology to semantically declare and describe functions ESWC 2016
4 Modeling, Generating, Publishing Knowledge as Linked Data EKAW 2017
5 Semi-automatic example-driven linked data mapping creation ISWC 2017
<http://ex.com/conf/{venue}>
bibo:Event

24. bibo:Document
bibo:presentedAt<http://ex.com/paper/1>
id title venue
1 Assessing & Refining Mappings to RDF to improve Dataset Quality ISWC 2015
2 RMLEditor : a graph-based editor for Linked Data mappings ESWC 2016
3 An ontology to semantically declare and describe functions ESWC 2016
4 Modeling, Generating, Publishing Knowledge as Linked Data EKAW 2017
5 Semi-automatic example-driven linked data mapping creation ISWC 2017
<http://ex.com/conf/ISWC2015>
bibo:Event

25. Who defines those rules?

26. <datafield tag="001#">
<subfield code="0">2,192</subfield>
</datafield>
<datafield tag="001A">
<subfield code="0">1961:22-06-88</subfield>
</datafield>
<datafield tag="001U">
<subfield code="0">utf8</subfield>
</datafield>
<datafield tag="002C">
<subfield code="a">tekst</subfield>
<subfield code="b">txt</subfield>
<subfield code="2">rdacontent/dut</subfield>
</datafield>
<datafield tag="002D">
<subfield code="a">zonder medium</subfield>
<subfield code="b">n</subfield>
<subfield code="2">rdamedia/dut</subfield>
</datafield>
<datafield tag="003#">
<subfield code="0">047268573</subfield>
</datafield>
<datafield tag="003O">
<subfield code="a">OCoLC</subfield>
<subfield code="0">64827916</subfield>
</datafield>
Sem
Web
dev

27. rr:subjectMap [
rr:template "http://data.kb.nl/ppn/{repox:metadata/record/datafield[@tag="003@"]/subfield[@code="0"]}";
rr:class ex:Record ];
rr:predicateObjectMap [
rr:predicate rdfs:label;
rr:objectMap [
rml:reference "repox:metadata/record/datafield[@tag="021A"]/subfield[@code="a"]";
rr:language "nl" ] ];
rr:predicateObjectMap [
rr:predicate dcterms:type;
rr:objectMap [ rml:reference "repox:metadata/record/datafield[@tag="002@"]/subfield[@code="0"]" ] ];
rr:predicateObjectMap [
rr:predicate dcterms:publisher;
rr:objectMap [ rml:reference "repox:metadata/record/datafield[@tag="033A"]/subfield[@code="n"]" ] ];
rr:predicateObjectMap [
rr:predicate rdfs:seeAlso;
rr:objectMap [ rr:template "http://www.worldcat.org/oclc/{metadata/record/datafield[@tag="003O"]/subfield[@code="0"]}"] ].
dataowner

28. RMLEditor: A Graph-Based Mapping Editor for Linked Data Mappings
P. Heyvaert, et al.

29. declaration
execution
assessment
declare
mapping rules
RML
Language

30. data owner
DB CSV XML JSON
RML
Linked
Data

31. data owner
DB CSV XML JSON
RML
RML
handler
RML
Processor
Linked
Data

32. Machine-interpretable dataset & service descriptions for
heterogeneous data access and retrieval. A. Dimou et al.
data owner
DB CSV XML JSON
RML
RML
handler
RML
Processor
Linked
Data
data
retrieval
handler

33. Machine-interpretable dataset & service descriptions for
heterogeneous data access and retrieval. A. Dimou et al.
data owner
table CSV XML JSON
RML
RML
handler
RML
Processor
source
desc
Linked
Data
data
retrieval
handler

34. “15th October 2017”
“2017-10-15”^^xsd:date
data owner
table CSV XML JSON
RML
RML
handler
RML
Processor
source
desc
Linked
Data
data
retrieval
handler

35. data owner
table CSV XML JSON
RML
RML
handler
RML
Processor
source
desc
Linked
Data
data
retrieval
handler
function
handler

36. An Ontology to Semantically Declare & Describe Functions
B.De Meester et al.
data owner
table CSV XML JSON
RML
FnO
RML
handler
RML
Processor
source
desc
Linked
Data
data
retrieval
handler
function
handler
GREL
DBpedia
functions

37. Automated Metadata Generation for Linked Data
Generation and Publishing Workflows. A. Dimou et al.
data owner
table CSV XML JSON
RML
FnO
RML
handler
RML
Processor
source
desc
metadata
handler
Linked
Data
meta
data
data
retrieval
handler
function
handler
GREL
DBpedia
functions

38. data owner
table CSV XML JSON
RML
FnO
RML
handler
RML
Processor
source
desc
metadata
handler
Linked
Data
meta
data
RMLMapper
data
retrieval
handler
function
handler
RML Mapper: a tool for uniform Linked Data generation
from heterogeneous data. A. Dimou et al.

39. declaration
execution
assessment
declaration
execution
assessment
RML
Mapper
execute
RML rules
RML rules
Linked
Data
data
declare
RML rules
RML
Language

40. bibo:Document
bibo:presentedAt<http://ex.com/paper/{id}>
id title venue
1 Assessing & Refining Mappings to RDF to improve Dataset Quality ISWC 2015
2 RMLEditor : a graph-based editor for Linked Data mappings ESWC 2016
3 An ontology to semantically declare and describe functions ESWC 2016
4 Modeling, Generating, Publishing Knowledge as Linked Data EKAW 2017
5 Semi-automatic example-driven linked data mapping creation ISWC 2017
<http://ex.com/conf/{venue}>
bibo:Event

41. foaf:Person
bibo:presentedAt<http://ex.com/paper/{id}>
id title venue
1 Assessing & Refining Mappings to RDF to improve Dataset Quality ISWC 2015
2 RMLEditor : a graph-based editor for Linked Data mappings ESWC 2016
3 An ontology to semantically declare and describe functions ESWC 2016
4 Modeling, Generating, Publishing Knowledge as Linked Data EKAW 2017
5 Semi-automatic example-driven linked data mapping creation ISWC 2017
<http://ex.com/conf/{venue}>
bibo:Proceedings

42. foaf:Person
bibo:presentedAt<http://ex.com/paper/1>
id title venue
1 Assessing & Refining Mappings to RDF to improve Dataset Quality ISWC 2015
2 RMLEditor : a graph-based editor for Linked Data mappings ESWC 2016
3 An ontology to semantically declare and describe functions ESWC 2016
4 Modeling, Generating, Publishing Knowledge as Linked Data EKAW 2017
5 Semi-automatic example-driven linked data mapping creation ISWC 2017
<http://ex.com/conf/ISWC2015>
bibo:Proceedings

43. What happens then?

44. foaf:Person
bibo:presentedAt<http://ex.com/paper/{id}>
id title venue
1 Assessing & Refining Mappings to RDF to improve Dataset Quality ISWC 2015
2 RMLEditor : a graph-based editor for Linked Data mappings ESWC 2016
3 An ontology to semantically declare and describe functions ESWC 2016
4 Modeling, Generating, Publishing Knowledge as Linked Data EKAW 2017
5 Semi-automatic example-driven linked data mapping creation ISWC 2017
<http://ex.com/conf/{venue}>
bibo:Proceedings
100 triples
2 violations/triple
200 violations!

45. foaf:Person
bibo:presentedAt<http://ex.com/paper/{id}>
id title venue
1 Assessing & Refining Mappings to RDF to improve Dataset Quality ISWC 2015
2 RMLEditor : a graph-based editor for Linked Data mappings ESWC 2016
3 An ontology to semantically declare and describe functions ESWC 2016
4 Modeling, Generating, Publishing Knowledge as Linked Data EKAW 2017
5 Semi-automatic example-driven linked data mapping creation ISWC 2017
<http://ex.com/conf/{venue}>
bibo:Proceedings
1,000,000 triples
2 violations/triple
2,000,000 violations!

46. foaf:Person
bibo:presentedAt<http://ex.com/paper/{id}>
id title venue
1 Assessing & Refining Mappings to RDF to improve Dataset Quality ISWC 2015
2 RMLEditor : a graph-based editor for Linked Data mappings ESWC 2016
3 An ontology to semantically declare and describe functions ESWC 2016
4 Modeling, Generating, Publishing Knowledge as Linked Data EKAW 2017
5 Semi-automatic example-driven linked data mapping creation ISWC 2017
<http://ex.com/conf/{venue}>
bibo:Proceedings
1,000,000 triples
2 violations/triple
2,000,000 violations!

47. You think this doesn’t happen?!

48. Conference
Year 2014 2015
Solution 1.1 swc:OrganizedEvent swc:OrganizedEvent
Solution 1.2 swc:Event bibo:Conference
Solution 1.3 swrc:Event swrc:Event
Solution 1.4 swrc:Event
Challenges as enablers for high quality Linked Data:
insights from the Semantic Publishing Challenge A. Dimou, et al.
Semantic Publishing
Challenge 2014 - 2016
statistics

49. Workshop
Year 2014 2015
Solution 1.1 bibo:Workshop bibo:Workshop
Solution 1.2 swc:Event bibo:Workshop
Solution 1.3 swrc:Event swrc:Workshop
Solution 1.4 swrc:Section
Challenges as enablers for high quality Linked Data:
insights from the Semantic Publishing Challenge A. Dimou, et al.
Semantic Publishing
Challenge 2014 - 2016
statistics

50. Paper
Year 2014 2015
Solution 1.1 swrc:InProceedings foaf:Document
Solution 1.2 bibo:Article swrc:InProceedings
Solution 1.3 swrc:Publication swrc:Publication
Solution 1.4 swc:Paper
Challenges as enablers for high quality Linked Data:
insights from the Semantic Publishing Challenge A. Dimou, et al.
Semantic Publishing
Challenge 2014 - 2016
statistics

51. Can we prevent violations?

52. RML
Mapper
DQA
Linked
Data
data
RML
violations

53. RML
Mapper
violations
MDQA
Linked
Data
data
RML
Assessing and Refining Mappings to RDF to
Improve Dataset Quality. A. Dimou et al.

54. new
RML
RML
Mapper
Mapping
Refinementsviolations
MDQA
(optional)
Linked
Data
data
RML

55. DBpedia
Use Case

56. Sustainable Linked Data Generation:
The case of DBpedia: W. Maroy et al.

57. Certain test cases require
a complete Linked Data set
DBpedia Quality Assessment
Linked Data: 16h
RML rules: 32s

58. new
RML
RML
Mapper
Mapping
Refinementsviolations
MDQA
(optional)
Linked
Data
data
RML

59. declaration
execution
assessment
RML
Mapper
execute
RML rules
RML
Validator
validate
RML rules
RML rules
validated
RML rules
Linked
Data
data
declare
RML rules
RML
Language

60. declaration
execution
assessment
RML
Mapper
execute
RML rules
administrate Linked Data generation workflow
RML
Workbench
RML
Validator
validate
RML rules
RML rules
validated
RML rules
Linked
Data
data
declare
RML rules
RML
Language

64. RML
Mapper
execute
RML rules
administrate Linked Data generation workflow
RML
Workbench
RML
Validator
validate
RML rules
RML rules
validated
RML rules
Linked
Data
data
declare
RML rules
RML
Language

65. Human agents do not need to
put in much effort to provide Linked Data

66. Human agents do not need to
put in much effort to provide Linked Data
Intelligent software agents
which function with Semantic Web technologies
will have enough Linked Data to work with

67. High Quality
Linked Data Generation
Dr Anastasia Dimou
Post-Doc researcher
imec.be - IDLab.technology
Anastasia.Dimou@imec.be
@natadimou