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Linked Data for Federation of OER Data & Repositories

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Linked Data for Federation of OER Data & Repositories

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An overview over different alternatives and opportunities of using Linked Data principles and datasets for federated access to distributed OER repositories. The talk was held at the ARIADNE/GLOBE convening (http://ariadne-eu.org/content/open-federations-2013-open-knowledge-sharing-education) at LAK 2013, Leuven, Belgium on 8 April 2013

An overview over different alternatives and opportunities of using Linked Data principles and datasets for federated access to distributed OER repositories. The talk was held at the ARIADNE/GLOBE convening (http://ariadne-eu.org/content/open-federations-2013-open-knowledge-sharing-education) at LAK 2013, Leuven, Belgium on 8 April 2013

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Linked Data for Federation of OER Data & Repositories

  1. 1. Motivation Data on the Web Some eyecatching opener illustrating growth and or diversity of web data Linked Data for Open Educational Data Sharing and Repository Federation Stefan Dietze (L3S Research Center, DE, @stefandietze, http://purl.org/dietze) Stefan Dietze 02/04/13
  2. 2. Linked Data  De-facto standard for sharing data on the Web  Vision: well connected graph of open Web data rNews  W3C standards (RDF, SPARQL) to expose data  Persistent URIs to interlink datasets Media Geo Ontology Ontology Number of Domain Triples % (Out-)Links % datasets Media 25 1,841,852,061 5.82 % 50,440,705 10.01 % Dublin Core Geographic 31 6,145,532,484 19.43 % 35,812,328 DBpedia 7.11 % Government 49 13,315,009,400 42.09 % 19,343,519 Ontology 3.84 % Publications 87 2,950,720,693 9.33 % 139,925,218 27.76 % Cross-domain 41 4,184,635,715 13.23 % 63,183,065 12.54 % Life sciences 41 3,036,336,004 9.60 % 191,844,090 38.06 % FOAF FMA BIBO User-generated 20 134,127,413 0.42 % 3,449,143 0.68 % Ontology content 295 31,634,213,770 503,998,829 Gene Ontology Source: http://lod-cloud.net/state, September 2011
  3. 3. Option 1: LD for integration of heterogeneous APIs & data Use case: biomedical education in Metamorphosis+ Tailored (L)CMS plugins => http://metamorphosis.med.duth.gr/ => http://www.meducator3.net/ Data/services integration & retrieval/search APIs ? Educational Web Resources
  4. 4. Option 1: LD for integration of heterogeneous APIs & data  Approach: 1) On the fly queries via “SmartLink” (Linked Data registry execution engine for open APIs) 2) Data lifting from heterogeneous repositories using “SmartLink” API and lifting specifications 3) Data enrichment (via DBpedia, Freebase, BioPortal) & clustering, eg to identify correlated resources  Goal: improvement of distributed (non-LD) data with public LOD vocabularies; tighter interlinking to provide coherent graph of educational data (across disparate stores) http://purl.org/smartlink  http://linkededucation.org/meducator Data/services integration & retrieval/search APIs Linked Educational Resources Schemas: OAI-DC, LOM, … Formats: XML, JSON Interfaces: OAI-PMH, REST, SOAP Educational Web Resources
  5. 5. Option 1: LD for integration of heterogeneous APIs & data LD vocabularies for disambiguation & clustering <led:Resource-BBC-519215> <led:title>…virus…</led:title> db:Life … Sciences </led:Resource-BBC-519215> db:Disease db:Viral db:Human Infections Papilloma Virus <led:Resource-mEducator-2139393292> <led:Resource-OpenLearn-2139393292> <led:title>Virtual patient 1002, <led:title>…viral…disease…</led:title> infections & HPV</led:title> … … </led:Resource-OpenLearn-2139393292> </led:Resource-mEducator-2139393292> Stefan Dietze 08/04/13
  6. 6. Option 1: LD for integration of heterogeneous APIs & data Some issues/challenges On-the-fly data integration, but issues wrt:  Annotation and description overhead: data lifting requires well-defined lifting specs for each API  Performance: distributed queries (multiple HTTP requests), on-the fly data lifting and processing  Scalability: decrease of query performance with increasing amount of repositories and/or data http://purl.org/smartlink  http://linkededucation.org/meducator Data/services integration & retrieval/search APIs Linked Educational Resources Schemas: OAI-DC, LOM, … Formats: XML, JSON Interfaces: OAI-PMH, REST, SOAP Educational Web Resources
  7. 7. Option 2: large-scale data harvesting and LD-ification Linked Data for automated cross-platform integration LD and non-LD data Step 1 – Alignment of types/properties ? <dc:title> <akt:has-title> OER VideoLecture LinkedUniversities Publication educational videos Step 2 – Linking of resources  6 million distinct (but linked) resources  97 million RDF triples  21.6 GB of data  Schema: http://data.linkededucation.org/ns/linked-education.rdf  SPARQL: http://data.linkededucation.org/request/linked-learning/sparql Mathieu d‘Aquin, Stefan Dietze 12/03/13 7
  8. 8. Option 2: large-scale data harvesting and LD-ification Linked Data for automated cross-platform integration LD and non-LD data Larger scale data processing, but issues wrt: Step 1 – Alignment of types/properties  Scalability and performance of data storage ? <dc:title> (potential solutions: applying distributed RDF storage, map/reduce etc) <akt:has-title> OER VideoLecture  Poor query performance (on large-scale datasets) LinkedUniversities Publication  Redundant data maintenance => periodic data imports educational videos Step 2 – Linking of resources  Maintenance of different identifiers (in case of non-LD sources: URIs vs internal IDs)  6 million distinct (but linked) resources  97 million RDF triples  21.6 GB of data  Schema: http://data.linkededucation.org/ns/linked-education.rdf  SPARQL: http://data.linkededucation.org/request/linked-learning/sparql Mathieu d‘Aquin, Stefan Dietze 12/03/13 8
  9. 9. Option 3: dataset cataloging and query federation LinkedUp approach [ http://linkedup-project.eu ]  “LinkedUp/Linked Education cloud” as (expanded) subset of LOD cloud: CKAN – “The DataHub” (http://datahub.io) for data collection in dedicated group “linked-education”  Public RDF vocabulary of datasets (“Linked Education Catalog”) (classification of datasets according to, eg, represented types, disciplines, data quality)  Additional integration datasets: dataset links and coreferences => providing a unified view on educational data => Linked Education Graph  Infrastructure, unified (SPARQL) endpoint & APIs for distributed/federated querying LinkedUp LinkedUp  Dataset Catalog  Data Interlinking & Correlation Educational Datasets Stefan Dietze 08/04/13
  10. 10. http://data.linkededucation.org/linkedup/catalog/ Linked Education Cloud & Catalog http://datahub.io/group/linked-education
  11. 11. Option 3: dataset cataloging and query federation Sparse knowledge / metadata about datasets http://datahub.io/group/linked-education http://datahub.io/dataset/lak-dataset Resource Types? Topics & disciplines? Quality & availability?
  12. 12. Option 3: dataset cataloging and query federation Co-occurence of (mapped) types Stefan Dietze 08/04/13
  13. 13. Option 3: dataset cataloging and query federation Dataset graph (according to type co-occurence) Stefan Dietze 08/04/13
  14. 14. Option 3: dataset cataloging and query federation Detection of topics and dataset DBpedia Category similarities Total Management 180 Academia 151 Top-ranked categories/topics Social_sciences 131 in Linked Education Catalog & Philosophy_of_science 125 their frequency Design 120 Sociology_index 117 Systems_science 117 Anthropology 116 Universities_and_colleges 116 Economics 114 Scientific_method 111 Approach Cognitive_science 110 Systems 107  Enriching sample Sociological_terms 104 resources from each Neuropsychological_assessment 100 dataset with DBpedia Concepts_in_metaphysics 96 entities/categories Developmental_psychology 93  Linking resources to LOD Political_philosophy 89 entities & categories via Cybernetics 88 Education 87 Philosophy_of_education 86 Arts 77 Critical_thinking 73 Biology 71 Political_science_termsDietze Stefan 02/04/13 71
  15. 15. Summary and outlook Summary  Different ways of using LD for federation of OER repositories  Linked Education data catalog (http://linkedup-project.eu, http://data.linkededucation.org/linkedup/catalog/): Linked Data-based catalog of open educational datasets (gradual addition of metadata about, eg, types, topics etc)  On the way: exposing non-LD educational data according to LD priniciples (eg LAK dataset) Future work  Data interlinking: complementary dataset of links between datasets and actual data/resources  Query federation and dedicated APIs  Exploitation in innovative educational scenarios and applications => LinkedUp Challenge (http://linkedup-challenge.org)  40.000 EUR price budget  Large network of organisations in LD & TEL  Dedicated data and support  Series of affiliated events at major conferences (www2013, ESWC2013, OKCON, LAK2013…) Stefan Dietze 08/04/13
  16. 16. LAK Challenge / LA & Linked Data Tutorial in a nutshell http://www.solaresearch.org/events/lak/lak-data-challenge/ http://linkedu.eu/event/lak2013-linkeddata-tutorial/ Stefan Dietze
  17. 17. Thank you! Contact  http://purl.org/dietze | @stefandietze See also (general)  http://linkedup-project.eu  http://linkedup-challenge.org http://linkededucation.org  http://linkeduniversities.org See also (data)  http://datahub.io/group/linked-education  http://data.linkededucation.org/linkedup/catalog /  http://www.solaresearch.org/resources/lak-dataset/  http://datahub.io/dataset/meducator Stefan Dietze 08/04/13

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