15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 1
Linked Open Data
State of the art, challenges and applications
Part o...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 2
Open Data
● What is Open Data?
– Non-proprietary and standard format
...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 3
What is Linked Open Data
● Open Data Distributed over the network
● S...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 4
Newcastle
City Council
Pollution data
City: Newcastle
Country: UK
Val...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 5
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 6
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 7
Issues
● Data quality
– Syntax error, invalid semantics
● Scalability...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 8
Issues
● Data quality
– Syntax error, invalid semantics
● Scalability...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 9
Data Quality
● Tim Berners-Lee LOD principles
● Syntactically valid
–...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 10
Data Quality
● Semantically valid
– Use standard vocabularies and on...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 11
Scalability
● Unavailable or unresponsive providers
– Non-dereferenc...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 12
Security
● Trust
– Community scoring of datasets and providers
– Pro...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 13
Currency
● Temporal context for data
– Facebook hits/day: average? S...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 14
Aggregation
● Co-reference
– Discovering co-referents
– Resolution o...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 15
Applications
● Open Government
● The Web Of Things
– Massive real-ti...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 16
Conclusion
● LOD is becoming a preferred solution for data providers...
15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 17
Questions ?
slide:question
en:noun
ens:part
slide:enquiry
owl:sameAs...
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Linked Open Data - State of the Art, Challenges and Applications

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Linked Open Data - State of the Art, Challenges and Applications

  1. 1. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 1 Linked Open Data State of the art, challenges and applications Part of the Linking Open (LOD) Data Project Cloud Diagram
  2. 2. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 2 Open Data ● What is Open Data? – Non-proprietary and standard format – Machine computable – Non-discriminatory
  3. 3. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 3 What is Linked Open Data ● Open Data Distributed over the network ● Standardised format – Resource Description Format (RDF) as data model – SPARQL for queries ● RDF “Triples” serialised as – XML, N3 or many other standards ● Semantics and Ontologies ● Architecture similar to WWW – Hypertext Transfer Protocol (HTTP) – Domain Name System (DNS) – Uniform Resource Identifiers (URIs) @prefix a: <http://example.com/2013/02/A#> . @prefix b: <http://example.net/2013/02/B#> . @prefix eg: <http://example.com/> . eg:sharedContent a:externalContent <http://somewhere/RDF/ont.owl> N3 RDF example
  4. 4. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 4 Newcastle City Council Pollution data City: Newcastle Country: UK Values: … Units: Measurements: … Compound: … Linked Open Data UK government World Health Organisation Government data City: Newcastle Population: … Lat: … Long: … Exposure levels Compound: Max Levels: … (more data) HTTP HTTP Data consumer
  5. 5. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 5
  6. 6. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 6
  7. 7. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 7 Issues ● Data quality – Syntax error, invalid semantics ● Scalability – Unavailability, unresponsiveness ● Security – Trust, Encryption ● Currency – Temporal context, versioning ● Aggregation – Co-referencing, source
  8. 8. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 8 Issues ● Data quality – Syntax error, invalid semantics ● Scalability – Unavailability, unresponsiveness ● Security – Trust, Encryption ● Currency – Temporal context, versioning ● Aggregation – Co-referencing, source
  9. 9. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 9 Data Quality ● Tim Berners-Lee LOD principles ● Syntactically valid – Several validators ● RDFAlerts, Vapour – Frameworks to build own tools ● Redland RDF (C library to build RDF parsers) – Allow to gather metrics on conformance ● Dataset scoring validator Data metrics
  10. 10. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 10 Data Quality ● Semantically valid – Use standard vocabularies and ontologies when possible – Use Domain specific vocabularies: ● eg SensorML for data-in-motion ● Vast amount for medicine, bioinformatics, etc. ● Linked Open Vocabularies database
  11. 11. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 11 Scalability ● Unavailable or unresponsive providers – Non-dereferenceable resources is missing data – LOD uses HTTP and WS ● HTTP status codes to convey more information – Redirect to other resources ● Caching ● Dataset dumps – Use analytics to provide useful information ● Profile servers ● Tune servers ● Plan scalability
  12. 12. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 12 Security ● Trust – Community scoring of datasets and providers – Provenance ● Watermarking – All attributes can be in meta-data ● Encrypted channels – SSL, certificates to ensure provenance consumer Trusted provider Trusted? Trusted?
  13. 13. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 13 Currency ● Temporal context for data – Facebook hits/day: average? Specific day? ● Is data versioned? – Are we mixing old and new data? ● Solutions: – Currency meta-data ● At the statement level, not just dataset level – Specific ontologies for current (OntoCurrency)
  14. 14. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 14 Aggregation ● Co-reference – Discovering co-referents – Resolution of co-referents ● Multiple sources – Discovery – SPARQL over remote datasets ● Software solutions – Semantic Web Client Library ● Handles dereferencing and aggregation – DARQ ● Multi-source SPARQL queries example.net example.com 1203 A P consumer Person A? http://example.com/ People/A http://example.net/ 2013/Staff/1203
  15. 15. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 15 Applications ● Open Government ● The Web Of Things – Massive real-time structured sensor data ● The DataHub ● Data.gov ● PublicData.eu ● Association mining ● Intelligent recommendation systems
  16. 16. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 16 Conclusion ● LOD is becoming a preferred solution for data providers ● Obstacles to the global, machine computable, linked Semantic Web ● No integrated solution dealing with all the issues ● But solutions exist – To deal with specific areas – To build new tools
  17. 17. 15/03/2013 Research Skills, MSc ITEC Rui M. Vieira 17 Questions ? slide:question en:noun ens:part slide:enquiry owl:sameAs speech:property rdfs:type

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