Mapping Hierarchical Sources into RDF using the RML Mapping Language
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The document discusses the RML (RDF Mapping Language), a scalable tool for mapping heterogeneous data sources into RDF, especially for data not originally formatted in RDF. It identifies issues with current mapping languages, such as R2RML, and proposes a more flexible and interoperable solution to support various data formats like JSON and XML. The text outlines practical applications and provides examples of how RML can process hierarchical data sources effectively.
![R2RML mapping document
NAME BIRTH_DATE DEATH_DATE
Robert Theodore McCall 1919-12-23 2010-02-26
Ronald Anderson 1929-12-06
Triples Map
Logical Table
Table Name
<#ArtistMapping>
rr:logicalTable
[
rr:tableName “ARTISTS”
].](https://image.slidesharecdn.com/rmlhierarchicalsourcesshort-140618174543-phpapp02/85/Mapping-Hierarchical-Sources-into-RDF-using-the-RML-Mapping-Language-14-320.jpg)
![R2RML mapping document
Triples Map
Subject Map
NAME BIRTH_DATE DEATH_DATE
Robert Theodore McCall 1919-12-23 2010-02-26
Ronald Anderson 1929-12-06
<#ArtistMapping>
rr:subjectMap [
rr:template “http://ex.com/{NAME}” ;
rr:class ex:Person ];
<http://ex.com/Robert+Theodore+McCall> a ex:Person](https://image.slidesharecdn.com/rmlhierarchicalsourcesshort-140618174543-phpapp02/85/Mapping-Hierarchical-Sources-into-RDF-using-the-RML-Mapping-Language-16-320.jpg)
![R2RML mapping document
Predicate Map
NAME BIRTH_DATE DEATH_DATE
Robert Theodore McCall 1919-12-23 2010-02-26
Ronald Anderson 1929-12-06
<#ArtistMapping>
rr:predicateObjectMap [
rr:predicate ex:birth_date;
rr:objectMap [
rr:column "BIRTH_DATE" ] ];
<http://ex.com/Robert+Theodore+McCall> ex:birth_date “1919-12-23”
Predicate Object Map
Objectt Map](https://image.slidesharecdn.com/rmlhierarchicalsourcesshort-140618174543-phpapp02/85/Mapping-Hierarchical-Sources-into-RDF-using-the-RML-Mapping-Language-17-320.jpg)
![[ ... …
{ "Title": "Apollo 11 Crew",
"Artist": "Ronald Anderson",
"Ref": "NPG_70_36",
"Sitter": [
{ "Name": "Neil Armstrong",
"Birth Date": "1930-08-05" },
{ "Name": "Buzz Aldrin",
"Birth Date": "1930-01-20" },
{ "Name": "Michael Collins" } ],
"DateOfWork": "1969" },
{ "Title": "Neil Armstrong",
"Artist": "Robert Theodore McCall",
"Ref": "S_NPG_2010_51",
"Sitter": [
{ "Name": "Neil Armstrong" } ],
"DateOfWork": "2009" },
... … ]
<Artists> ... ...
<Artist>
<Name>Robert Theodore McCall</Name>
<Birth_Date>1919-12-23</Birth_Date>
<Death_Date>2010-02-26</Death_Date>
</Artist>
<Artist>
<Name>Ronald Anderson</Name>
<Birth_Date>1929-12-06</Birth_Date>
<Death_Date/>
</Artist> ... ...
</Artists>
artworks.JSON artists.XML](https://image.slidesharecdn.com/rmlhierarchicalsourcesshort-140618174543-phpapp02/85/Mapping-Hierarchical-Sources-into-RDF-using-the-RML-Mapping-Language-23-320.jpg)
![Triples Map
Logical Source
source
<#ArtworkMapping>
rml:logicalSource
[rml:source “http://ex.com/artworks.json”].
Triples Map
Logical Source
source
<#ArtistMapping>
rml:logicalSource
[ rml:source “artists.xml” ].](https://image.slidesharecdn.com/rmlhierarchicalsourcesshort-140618174543-phpapp02/85/Mapping-Hierarchical-Sources-into-RDF-using-the-RML-Mapping-Language-25-320.jpg)
![<#ArtworkMapping>
rml:logicalSource
[ rml:source “http://ex.com/artworks.json” ;
rml:rererenceFormulation ql:JSONPath ].
Triples Map
Logical Source
source
<#ArtistMapping>
rml:logicalSource
[ rml:source “artists.xml”;
rml:referenceFormulation ql:XPath ].Reference Formulation
Triples Map
Logical Source
source
Reference Formulation](https://image.slidesharecdn.com/rmlhierarchicalsourcesshort-140618174543-phpapp02/85/Mapping-Hierarchical-Sources-into-RDF-using-the-RML-Mapping-Language-27-320.jpg)
![<#ArtistMapping>
rml:logicalSource
[ rml:source “artists.xml”;
rml:referenceFormulation ql:Xpath ;
rml:iterator “/Artists/Artist” ].
<Artists> ... ...
<Artist>
<Name>Robert Theodore McCall</Name>
<Birth_Date>1919-12-23</Birth_Date>
<Death_Date>2010-02-26</Death_Date>
</Artist>
<Artist>
<Name>Ronald Anderson</Name>
<Birth_Date>1929-12-06</Birth_Date>
<Death_Date/>
</Artist> ... ...
</Artists>](https://image.slidesharecdn.com/rmlhierarchicalsourcesshort-140618174543-phpapp02/85/Mapping-Hierarchical-Sources-into-RDF-using-the-RML-Mapping-Language-29-320.jpg)
![[ ... …
{ "Title": "Apollo 11 Crew",
"Artist": "Ronald Anderson",
"Ref": "NPG_70_36",
"Sitter": [
{ "Name": "Neil Armstrong",
"Birth Date": "1930-08-05" },
{ "Name": "Buzz Aldrin",
"Birth Date": "1930-01-20" },
{ "Name": "Michael Collins" } ],
"DateOfWork": "1969" },
{ "Title": "Neil Armstrong",
"Artist": "Robert Theodore McCall",
"Ref": "S_NPG_2010_51",
"Sitter": [
{ "Name": "Neil Armstrong" } ],
"DateOfWork": "2009" },
... … ]
<#ArtworkMapping>
rml:logicalSource
[ rml:source “http://ex.com/artworks.json” ;
rml:rererenceFormulation ql:JSONPath ;
rml:iterator “$.[*]” ].
<#SitterMapping>
rml:logicalSource
[ rml:source “http://ex.com/artworks.json”;
rml:rererenceFormulation ql:JSONPath ;
rml:iterator “$.[*].Sitter” ].](https://image.slidesharecdn.com/rmlhierarchicalsourcesshort-140618174543-phpapp02/85/Mapping-Hierarchical-Sources-into-RDF-using-the-RML-Mapping-Language-30-320.jpg)
![<#ArtistMapping>
rml:logicalSource
[ rml:source “http://ex.com/artists.xml”;
rml:rererenceFormulation ql:XPath ;
rml:iterator “/Artists/Artist” ] ;
rr:subjectMap [
rr:template
“http://ex.com/{Name}”
];
rr:predicateObjectMap [
rr:predicate ex:death_date ;
rr:objectMap [
rml:reference
“/Artists/Artist/Death_Date”] ].
<Artists> ... ...
<Artist>
<Name>Robert Theodore McCall</Name>
<Birth_Date>1919-12-23</Birth_Date>
<Death_Date>2010-02-26</Death_Date>
</Artist>
<Artist>
<Name>Ronald Anderson</Name>
<Birth_Date>1929-12-06</Birth_Date>
<Death_Date/>
</Artist> ... ...
</Artists>
<http://ex.com/Robert+Theodore+McCall>
ex:death_date “1929-12-06”.](https://image.slidesharecdn.com/rmlhierarchicalsourcesshort-140618174543-phpapp02/85/Mapping-Hierarchical-Sources-into-RDF-using-the-RML-Mapping-Language-32-320.jpg)
![[ ... …
{ "Title": "Apollo 11 Crew",
"Artist": "Ronald Anderson",
"Ref": "NPG_70_36",
"Sitter": [
{ "Name": "Neil Armstrong",
"Birth Date": "1930-08-05" },
{ "Name": "Buzz Aldrin",
"Birth Date": "1930-01-20" },
{ "Name": "Michael Collins" } ],
"DateOfWork": "1969" },
{ "Title": "Neil Armstrong",
"Artist": "Robert Theodore McCall",
"Ref": "S_NPG_2010_51",
"Sitter": [
{ "Name": "Neil Armstrong" } ],
"DateOfWork": "2009" },
... … ]
<#ArtworkMapping>
rml:logicalSource
[ rml:source “http://ex.com/artworks.json”;
rml:rererenceFormulation ql:JSONPath ;
rml:iterator “$.[*]” ] ;
rr:subjectMap [
rr:template
“http://ex.com/{Ref}”];
rr:predicateObjectMap [
rr:predicate rdfs:label ;
rr:objectMap [
rml:reference “$.[*].Title” ]
].
<http://ex.com/NPG_70_36>
rdfs:label “Apollo 11 Crew”.](https://image.slidesharecdn.com/rmlhierarchicalsourcesshort-140618174543-phpapp02/85/Mapping-Hierarchical-Sources-into-RDF-using-the-RML-Mapping-Language-33-320.jpg)
![[ ... …
{ "Title": "Apollo 11 Crew",
"Artist": "Ronald Anderson",
"Ref": "NPG_70_36",
"Sitter": [
{ "Name": "Neil Armstrong",
"Birth Date": "1930-08-05" },
{ "Name": "Buzz Aldrin",
"Birth Date": "1930-01-20" },
{ "Name": "Michael Collins" } ],
"DateOfWork": "1969" },
{ "Title": "Neil Armstrong",
"Artist": "Robert Theodore McCall",
"Ref": "S_NPG_2010_51",
"Sitter": [
{ "Name": "Neil Armstrong" } ],
"DateOfWork": "2009" },
... … ]
<#SitterMapping>
rml:logicalSource
[ rml:source “http://ex.com/artworks.json”;
rml:rererenceFormulation ql:JSONPath ;
rml:iterator “$.[*].Sitter” ] ;
rr:subjectMap [
rr:template
“http://ex.com/{Name}”];
rr:predicateObjectMap [
rr:predicate ex:birth_date ;
rr:objectMap [
rml:reference “$.[*].Sitter.Birth Date” ]].
<http://ex.com/Neil+Armstrong>
ex:birth_date “1930-08-05”.](https://image.slidesharecdn.com/rmlhierarchicalsourcesshort-140618174543-phpapp02/85/Mapping-Hierarchical-Sources-into-RDF-using-the-RML-Mapping-Language-34-320.jpg)
Mapping Hierarchical Sources into RDF using the RML Mapping Language
- 1. Mapping Hierarchical Sources into RDF using the RML Mapping Language Anastasia Dimou1, Miel Vander Sande1, Jason Slepicka2, Pedro Szekely2, Erik Mannens1, Craig Knoblock2, Rik Van de Walle1 1Ghent University – iMinds – Multimedia Lab 2University of Southern California – Information Science Institute – Department of Computer Science http://rml.io IEEE-ICSC14 Newport beach, California, 18th June 2014
- 2. Most of the data that we would like to be able to query as Linked Open Data exists in formats other than RDF
- 3. There are… over 11,000 APIs according to ProgrammableWeb.org only 74 of which return results in RDF But more than 5000 return results in JSON or XML
- 4. Many languages, tools and approaches were proposed to convert data from relational databases to RDF
- 5. Relational Database to RDF (R2RML W3C) R2RML mappings R2RML processor Data OWNER / PUBLISHER defines RDF DB
- 7. R2RML mappings R2RML processor Data OWNER / PUBLISHER defines RDF DB CSV JSONXML RDF RDF RDF
- 8. lack of uniform definitions to describe mapping rules for heterogeneous sources lack of interoperable definitions that would allow the re-use of mapping rules across different implementations lack of reusable definitions that would allow the re-use of mapping rules for representing data in the same or different formats
- 9. mapping data on a per-source and per-format basis or on case-specific basis Uniform way of defining mappings for heterogeneous sources that can be re-used across data in the same or different formats and be interoperable across different implementations
- 10. R2RML mappings R2RML processor Data OWNER / PUBLISHER defines RDF DB CSV JSONXML RDF RDF RDF
- 11. Mappings definitions processor Data OWNER / PUBLISHER defines RDF DB CSV JSONXML any format to RDF
- 12. RDF Mapping Language (RML) generic scalable mapping language for mapping heterogeneous resources into RDF in an integrable and interoperable fashion superset of the W3C standardized R2RML mapping language http://semweb.mmlab.be/ns/rml
- 13. Relational Database to RDF Mapping Language (R2RML)
- 14. R2RML mapping document NAME BIRTH_DATE DEATH_DATE Robert Theodore McCall 1919-12-23 2010-02-26 Ronald Anderson 1929-12-06 Triples Map Logical Table Table Name <#ArtistMapping> rr:logicalTable [ rr:tableName “ARTISTS” ].
- 15. R2RML mapping definition Table Name Triples Map Logical Table Subject Map Predicate-Object Map Predicate-Object Map Predicate-Object Map Predicate Map Object Map
- 16. R2RML mapping document Triples Map Subject Map NAME BIRTH_DATE DEATH_DATE Robert Theodore McCall 1919-12-23 2010-02-26 Ronald Anderson 1929-12-06 <#ArtistMapping> rr:subjectMap [ rr:template “http://ex.com/{NAME}” ; rr:class ex:Person ]; <http://ex.com/Robert+Theodore+McCall> a ex:Person
- 17. R2RML mapping document Predicate Map NAME BIRTH_DATE DEATH_DATE Robert Theodore McCall 1919-12-23 2010-02-26 Ronald Anderson 1929-12-06 <#ArtistMapping> rr:predicateObjectMap [ rr:predicate ex:birth_date; rr:objectMap [ rr:column "BIRTH_DATE" ] ]; <http://ex.com/Robert+Theodore+McCall> ex:birth_date “1919-12-23” Predicate Object Map Objectt Map
- 19. RDF Mapping Language (RML) mapping hierarchical sources to RDF deal with hierarchy and heterogeneity
- 20. R2RML: each row is a self-contained that can be processed independently R2RML: the columns in each row can be referred to unambiguously R2RML: for each reference to a column in a single row a unique value is returned
- 21. explicit reference to the iteration pattern R2RML: each row is a self-contained that can be processed independently abstract reference to the input data R2RML: the columns in each row can be referred to unambiguously more than one triples per Predicate-Object Map R2RML: for each reference to a column in a single row a unique value is returned
- 22. RDF Mapping Language (RML) For hierarchical sources
- 23. [ ... … { "Title": "Apollo 11 Crew", "Artist": "Ronald Anderson", "Ref": "NPG_70_36", "Sitter": [ { "Name": "Neil Armstrong", "Birth Date": "1930-08-05" }, { "Name": "Buzz Aldrin", "Birth Date": "1930-01-20" }, { "Name": "Michael Collins" } ], "DateOfWork": "1969" }, { "Title": "Neil Armstrong", "Artist": "Robert Theodore McCall", "Ref": "S_NPG_2010_51", "Sitter": [ { "Name": "Neil Armstrong" } ], "DateOfWork": "2009" }, ... … ] <Artists> ... ... <Artist> <Name>Robert Theodore McCall</Name> <Birth_Date>1919-12-23</Birth_Date> <Death_Date>2010-02-26</Death_Date> </Artist> <Artist> <Name>Ronald Anderson</Name> <Birth_Date>1929-12-06</Birth_Date> <Death_Date/> </Artist> ... ... </Artists> artworks.JSON artists.XML
- 24. Specifying the input data R2RML: database RML: file, API, … R2RML: Logical Table (rr:logicalTable) RML: Logical Source (rml:logicalSource) R2RML: logical Name (rr:logicalName) RML: source (rml:source)
- 25. Triples Map Logical Source source <#ArtworkMapping> rml:logicalSource [rml:source “http://ex.com/artworks.json”]. Triples Map Logical Source source <#ArtistMapping> rml:logicalSource [ rml:source “artists.xml” ].
- 26. Referring to the input data R2RML: databases RML: XML or JSON or CSV or …. R2RML: (SQL) RML: Xpath/Xquery or JSONPath or RFC 4180 or … R2RML: (rr:sqlQuery) RML: rml:referenceFormulation
- 27. <#ArtworkMapping> rml:logicalSource [ rml:source “http://ex.com/artworks.json” ; rml:rererenceFormulation ql:JSONPath ]. Triples Map Logical Source source <#ArtistMapping> rml:logicalSource [ rml:source “artists.xml”; rml:referenceFormulation ql:XPath ].Reference Formulation Triples Map Logical Source source Reference Formulation
- 28. Iterating over the input data R2RML: per row RML: ? R2RML: RML: rml:iterator
- 29. <#ArtistMapping> rml:logicalSource [ rml:source “artists.xml”; rml:referenceFormulation ql:Xpath ; rml:iterator “/Artists/Artist” ]. <Artists> ... ... <Artist> <Name>Robert Theodore McCall</Name> <Birth_Date>1919-12-23</Birth_Date> <Death_Date>2010-02-26</Death_Date> </Artist> <Artist> <Name>Ronald Anderson</Name> <Birth_Date>1929-12-06</Birth_Date> <Death_Date/> </Artist> ... ... </Artists>
- 30. [ ... … { "Title": "Apollo 11 Crew", "Artist": "Ronald Anderson", "Ref": "NPG_70_36", "Sitter": [ { "Name": "Neil Armstrong", "Birth Date": "1930-08-05" }, { "Name": "Buzz Aldrin", "Birth Date": "1930-01-20" }, { "Name": "Michael Collins" } ], "DateOfWork": "1969" }, { "Title": "Neil Armstrong", "Artist": "Robert Theodore McCall", "Ref": "S_NPG_2010_51", "Sitter": [ { "Name": "Neil Armstrong" } ], "DateOfWork": "2009" }, ... … ] <#ArtworkMapping> rml:logicalSource [ rml:source “http://ex.com/artworks.json” ; rml:rererenceFormulation ql:JSONPath ; rml:iterator “$.[*]” ]. <#SitterMapping> rml:logicalSource [ rml:source “http://ex.com/artworks.json”; rml:rererenceFormulation ql:JSONPath ; rml:iterator “$.[*].Sitter” ].
- 31. Referring to the extracts of the input data explicitly and implicitly R2RML: column name RML: XML element or JSON object or … R2RML: rr:column RML: rml:reference
- 32. <#ArtistMapping> rml:logicalSource [ rml:source “http://ex.com/artists.xml”; rml:rererenceFormulation ql:XPath ; rml:iterator “/Artists/Artist” ] ; rr:subjectMap [ rr:template “http://ex.com/{Name}” ]; rr:predicateObjectMap [ rr:predicate ex:death_date ; rr:objectMap [ rml:reference “/Artists/Artist/Death_Date”] ]. <Artists> ... ... <Artist> <Name>Robert Theodore McCall</Name> <Birth_Date>1919-12-23</Birth_Date> <Death_Date>2010-02-26</Death_Date> </Artist> <Artist> <Name>Ronald Anderson</Name> <Birth_Date>1929-12-06</Birth_Date> <Death_Date/> </Artist> ... ... </Artists> <http://ex.com/Robert+Theodore+McCall> ex:death_date “1929-12-06”.
- 33. [ ... … { "Title": "Apollo 11 Crew", "Artist": "Ronald Anderson", "Ref": "NPG_70_36", "Sitter": [ { "Name": "Neil Armstrong", "Birth Date": "1930-08-05" }, { "Name": "Buzz Aldrin", "Birth Date": "1930-01-20" }, { "Name": "Michael Collins" } ], "DateOfWork": "1969" }, { "Title": "Neil Armstrong", "Artist": "Robert Theodore McCall", "Ref": "S_NPG_2010_51", "Sitter": [ { "Name": "Neil Armstrong" } ], "DateOfWork": "2009" }, ... … ] <#ArtworkMapping> rml:logicalSource [ rml:source “http://ex.com/artworks.json”; rml:rererenceFormulation ql:JSONPath ; rml:iterator “$.[*]” ] ; rr:subjectMap [ rr:template “http://ex.com/{Ref}”]; rr:predicateObjectMap [ rr:predicate rdfs:label ; rr:objectMap [ rml:reference “$.[*].Title” ] ]. <http://ex.com/NPG_70_36> rdfs:label “Apollo 11 Crew”.
- 34. [ ... … { "Title": "Apollo 11 Crew", "Artist": "Ronald Anderson", "Ref": "NPG_70_36", "Sitter": [ { "Name": "Neil Armstrong", "Birth Date": "1930-08-05" }, { "Name": "Buzz Aldrin", "Birth Date": "1930-01-20" }, { "Name": "Michael Collins" } ], "DateOfWork": "1969" }, { "Title": "Neil Armstrong", "Artist": "Robert Theodore McCall", "Ref": "S_NPG_2010_51", "Sitter": [ { "Name": "Neil Armstrong" } ], "DateOfWork": "2009" }, ... … ] <#SitterMapping> rml:logicalSource [ rml:source “http://ex.com/artworks.json”; rml:rererenceFormulation ql:JSONPath ; rml:iterator “$.[*].Sitter” ] ; rr:subjectMap [ rr:template “http://ex.com/{Name}”]; rr:predicateObjectMap [ rr:predicate ex:birth_date ; rr:objectMap [ rml:reference “$.[*].Sitter.Birth Date” ]]. <http://ex.com/Neil+Armstrong> ex:birth_date “1930-08-05”.
- 35. RDF Mapping Language (RML) Source Triples Map Logical Source Subject Map Predicate-Object Map Predicate Map Object Map Term Map template constant reference Iterator Reference Formulation Referencing Object Map Triples Map Join Condition Parent column Child column
- 36. RDF Mapping Language (RML) Editing mappings with Karma http://www.isi.edu/integration/karma/
- 39. mapping-driven processing: processing driven by the mapping module data-driven processing: processing driven by the extraction module
- 40. Extraction Module Mapping Module RML Processor
- 41. Mapping Hierarchical Sources into RDF using the RML mapping language RML: http://rml.io RML Namespace: http://semweb.mmlab.be/ns/rml RML Processor: https://github.com/mmlab/RMLProcessor Contact us Anastasia Dimou [email protected] @natadimou Miel Vander Sande [email protected] @Miel_vds