Behshid BehkamalBehshid Behkamal

Ferdowsi University of MashhadFerdowsi University of MashhadWeb Technology LabWeb Technology Lab

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OutlineOutline

1. Linked Data: What and Why1. Linked Data: What and Why

2. Linking Open Data Project2. Linking Open Data Project

3. An Experience of Publishing Linked Data3. An Experience of Publishing Linked Data

4. Challenges of Linked Data4. Challenges of Linked Data

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The problem: Doing PhD in a good university

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The problem: Planning a trip

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The Web of Documents The Web of Documents

The Web of Data The Web of Data

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Linked Data is …

A way of publishing data on the web to create typed links between data from different sources

WikipediaWikipedia:

A term used to describe a recommended best practice for exposing, sharing, and connecting pieces of datadata, informationinformation, and knowledgeknowledge on the Semantic Web using URIs and RDF

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Linked Data employs …

URI URI to identify resource

HTTPHTTP protocol to retrieve resource

RDFRDF data model to represent resource

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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

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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 networkDescription of a rabbits

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RDF ModelIt is a machine understandable metadata

A model is a collection of statements

Statement := (subject, predicate, object)Statement := (subject, predicate, object)

Subject Object

Predicate

StatementStatement

URI

URI

URI / Literal

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Linking Statements

The subject of one statement can be the object of another

Behkamal ComputerEngineering

Student OF

Ferdowsi university of

Mashhadwww.um.ac.ir

Department OF

Has HomePage

Such collections of statements form LOD cloud

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LOD Cloud : May 2007

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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

Datasets are published based on Linked Data PrinciplesLinked Data Principles

Datasets are interlinked with at least oneat least one other dataset in the cloud

Some datasets act as hubE.g. DBpedia, Geonames, …

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LOD Cloud : February 2008

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LOD Cloud : July 2009

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LOD Cloud : September 2010

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LOD cloud : 2007 - 2010

Datasets: Datasets: only 11 more than 200200Triples:Triples: around 22 Billion over 2525 Billion

Links:Links: over 22 Million around 395395 Million

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Process of publishing FUM-LD

1. Selecting Target Data

2. Assigning URIs

3. Publishing Data

4. Interlinking Data Resources

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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:

FacultyFacultyDepartmentDepartmentProfessorProfessorPaperPaperCourseCourse

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2. Assigning URLs - We used a simplea simple schemaschema for naming URIs

- http://wtlab.um.ac.ir/LinkedOpenData/TYPETYPE/ID

Faculty: Faculty: http://wtlab.um.ac.ir/LinkedOpenData/faculties/engineeringDepartment: Department: http://wtlab.um.ac.ir/LinkedOpenData/departments/3105 Professor: Professor: http://wtlab.um.ac.ir/LinkedOpenData/profs/kahani Paper: Paper: http://wtlab.um.ac.ir/LinkedOpenData/papers/13 Course: Course: http://wtlab.um.ac.ir/LinkedOpenData/courses/23152183

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3. Publishing Data

Methods for publishingMethods for publishing Using existing toolsUsing existing tools Developing an applicationDeveloping an application

Modes of publishingModes of publishing Online (On the fly)Online (On the fly) OfflineOffline

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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

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4.1. Interlinking to FUM-LD Resources

Departments Courses

Profs

PapersFaculties

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4.2. Linking to Other Resources

Datasets Description Count

DBpedia Links to Resources 4570

DBpedia owl:sameAs links 1311

DBLP owl:sameAs links 475

ACM owl:sameAs links 38

DBpedia skos:subject links 3708

OpenCyc skos:subject links 449

GeoNames Links to resources 936

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سيستم کيفيت ارزيابي برای شده ارائه مدلهايالکترونيکي تجارت هاي

Classification of ChallengesClassification of Challenges

Data Challenges

Multi Lingual challenges

Linking challenges

Data and Link Maintenance

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1. Linking Challenges Choosing appropriate ontologies and predicatesSelecting based on popularity

Not effective for all cases No automatic approach

Creating appropriate links between dataFinding appropriate links between resources of different

datasets

‘Hasan Amiri’ , ‘S.H. Amiri’ and ‘Amiri H.’

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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

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3. Multi Lingual challenges

Linking a Non-English dataset to the related English datasets of LOD cloud.

Multi-lingualMulti-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 SpellingMulti Spelling Some Persian name like “سعید” is entered as “saeed” , “saeid” and

“saied”.

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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 itemsUpdating data as well as links between the data items

Two main situations that requires updating the datasetTwo 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

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Summery

Linked Data and LOD cloud are introduces

An experience of publishing linked data is presented

Some problems and challenges are discussed

Behshid Behshid BehkamalBehkamal