1. Behshid Behkamal Ferdowsi University of Mashhad Web Technology Lab

2. 2 Outline 1. Linked Data: What and Why 2. Linking Open Data Project 3. An Experience of Publishing Linked Data 4. Challenges of Linked Data

3. 3 The problem: Doing PhD in a good university

4. 4 The problem: Planning a trip

5. 5 The Web of Documents The Web of Data

6. 6 Linked Data is … A way of publishing data on the web to create typed links between data from different sources Wikipedia Wikipedia: datainformationknowledge A term used to describe a recommended best practice for exposing, sharing, and connecting pieces of data, information, and knowledge on the Semantic Web using URIs and RDF

7. 7 Linked Data employs … URI URI to identify resource HTTP HTTP protocol to retrieve resource RDF RDF data model to represent resource

8. 8 URI: Uniform Resource Identifier As names for any entity existing in the world A simple and extensible means for identifying a resource For documents and other entities that can be located on the Web

9. 9 HTTP A simple mechanism for retrieving Resources that can be serialized as a stream of bytes  Picture of an animal Descriptions of entities that cannot themselves be sent across network  Description of a rabbits

10. 10 RDF Model It is a machine understandable metadata A model is a collection of statements Statement := (subject, predicate, object) Subject Object Predicate Statement URI URI / Literal

11. 11 Linking Statements The subject of one statement can be the object of another Behkamal Computer Engineering Student OF Ferdowsi university of Mashhad www.um.ac.ir Department OF Has HomePage Such collections of statements form LOD cloud

12. 12 LOD Cloud : May 2007

13. 13 Linked Open Data (LOD) Cloud Each circle represents a dataset  Size of the circle corresponds to the number of triples  Arrows represent the links between datasets  Thickness of arrows indicates number of links Linked Data Principles Datasets are published based on Linked Data Principles at least one Datasets are interlinked with at least one other dataset in the cloud Some datasets act as hub  E.g. DBpedia, Geonames, …

14. 14 LOD Cloud : February 2008 14

15. 15 LOD Cloud : July 2009 15

16. 16 LOD Cloud : September 2010

17. 17 LOD cloud : 2007 - 2010 Datasets: 1200 Datasets: only 1  more than 200 Triples: 2 25 Triples: around 2 Billion  over 25 Billion Links: 2395 Links: over 2 Million  around 395 Million

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19. 19 Process of publishing FUM-LD 1. Selecting Target Data 2. Assigning URIs 3. Publishing Data 4. Interlinking Data Resources

20. 20 1. Selecting Target Data - An important issue of publishing linked data is deciding which data is to be selected - After studying the FUM data base, five important entities are selected:FacultyDepartmentProfessorPaperCourse

21. 21 2. Assigning URLs a simpleschema - We used a simple schema for naming URIs TYPE - http://wtlab.um.ac.ir/LinkedOpenData/TYPE/ID Faculty: faculties Faculty: http://wtlab.um.ac.ir/LinkedOpenData/faculties/engineeringfacultieshttp://wtlab.um.ac.ir/LinkedOpenData/faculties/engineering Department: departments Department: http://wtlab.um.ac.ir/LinkedOpenData/departments/3105departmentshttp://wtlab.um.ac.ir/LinkedOpenData/departments/3105 Professor: /profs Professor: http://wtlab.um.ac.ir/LinkedOpenData/profs/kahani/profshttp://wtlab.um.ac.ir/LinkedOpenData/profs/kahani Paper: papers Paper: http://wtlab.um.ac.ir/LinkedOpenData/papers/13papershttp://wtlab.um.ac.ir/LinkedOpenData/papers/13 Course: courses Course: http://wtlab.um.ac.ir/LinkedOpenData/courses/23152183courseshttp://wtlab.um.ac.ir/LinkedOpenData/courses/23152183

22. 22 3. Publishing Data Methods for publishing Methods for publishing Using existing tools Using existing tools Developing an application Developing an application Modes of publishing Online (On the fly) Online (On the fly) Offline Offline  

23. 23 Providing links to other resources inside and outside the FUM-LD is a main design target of our web presentation 4.1. Interlinking to FUM-LD Resources 4.2. Linking to External Datasets DBPedia Geonames YAGO DBLP … 4. Linking Data Resources

24. 24 4.1. Interlinking to FUM-LD Resources Departments Courses Profs Papers Faculties

25. 25 4.2. Linking to Other Resources DatasetsDescriptionCount DBpediaLinks to Resources4570 DBpediaowl:sameAs links1311 DBLPowl:sameAs links475 ACMowl:sameAs links38 DBpediaskos:subject links3708 OpenCycskos:subject links449 GeoNamesLinks to resources936

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27. 27 مدلهاي ارائه شده برای ارزيابي کيفيت سيستم هاي تجارت الکترونيکي Classification of Challenges Data Challenges Multi Lingual challenges Linking challenges Data and Link Maintenance

28. 28 1. Linking Challenges Choosing appropriate ontologies and predicates Selecting based on popularity  Not effective for all cases  No automatic approach Creating appropriate links between data Finding appropriate links between resources of different datasets  ‘Hasan Amiri’, ‘S.H. Amiri’ and ‘Amiri H.’

29. 29 Lack of required data in the original dataset  No information for publications of some professors Incorrect or incomplete data  abstract or keywords, or list of coauthors of the papers Inconsistency of data value  Different types of formats (date of a conference)  Different language 2. Data Challenges lack of data or presence of low-quality data

30. 30 3. Multi Lingual challenges Linking a Non-English dataset to the related English datasets of LOD cloud.Multi-lingual Some users choose their mother tongue language while others use English for entering their data Because of  Convenience of users  Users’ field of activity Multi Spelling Some Persian name like “سعید” is entered as “saeed”, “saeid” and “saied”.

31. 31 4. Data and Link Maintenance An important issue in maintaining the quality of data published as linked data is: Updating data as well as links between the data items Two main situations that requires updating the dataset The original dataset is changed Exp. A new professor joins Computer Engineering department A related external dataset is changed Exp. A new resource describing ‘Computer Engineering Department of Ferdowsi University o Mashhad’ is added to DBpedia

32. 32 Summery  Linked Data and LOD cloud are introduces  An experience of publishing linked data is presented  Some problems and challenges are discussed

33. Behshid Behkamal