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[hemmerling] Linked Data & Linked Open Data ( LOD )

Organisations, Events, Awards, Competitions

Course "Semantic Web Technologies"

Semantic Technologies


    1. Use URIs as names for things.
    2. Use HTTP URIs so that people can look up those names.
    3. When someone looks up a URI, provide useful information, using the standards (RDF*, SPARQL).
    4. Include links to other URIs. so that they can discover more things.

The majority of examples in this book is shown in the Turtle serialisation of RDF,
for readability;
however, if data is published using just one serialisation format,
this should be RDF/XML,
as it is widely supported by tools that consume Linked Data.

The simplicity of N-Triples makes it popular for teaching people about RDF, and some parsers can read it more quickly because they have less work to do,
but the format's verbosity makes it less popular than the other formats.

.. once Turtle becomes a W3C standard, we'll see less and less use of RDF/XML. AS of this writing,
though, it's still the only standardized RDF serialization format.

If your're defining a fairly simple vocabulary primarily for your own use... and if your're concerned primarily with the striped nature of RDF/XML, you'll most likely want to just define your vocabulary in RDF and RDFS.

However, if you're documenting a model of a specific domain and you hope to encourage others to use it and, best of all, be able to use your data to make sophisticated queries, you're goint to want to use OWL to make advantage of its many inferential enhancements.

Expression ( Serialisation ) of RDF Formats

Object-Oriented System vs. RDF


  • By adding one property ( e.g. “drivesBicycle” ) to the metadata about an existing resource ( of “Rolf” ), that resource becomes a member of the class ( “Driver” ) that it wasn't a member before.
  • The ability of RDF resoures to become members of classes based on their data values has made semantic web technology popular in some industries ( e.g. medical research ). Researchers may accumulate data with little apparent structure and then see what structure turns out to be there - that is, which resources turn out to be member of which classes, and what their relationships are.
  • RDF lets you define classes as subclasses of other ones, and unlike object-oriented systems, properties of subproperties of other ones. E.g: If xy:Driver is a subclass of foaf:Person, a query for the phone numbers of all foaf:Person instances, the result include Rolf's phone number, because beeing in the class of drivers Rolf is also in the class of persons.

Object-Oriented System

  • I have to declare a instance of a class ( e.g of the class “driver” ) and then assign it all the details about “Rolf”

Topic Maps vs. RDF

Suggestion for Proceeding in your own Project

Simple approach to use ARQ in own Project, Prototyping Stage

  1. Perfom SPARQL queries with ARQ. Execute ARQ by batch ( script ) language.
  2. Save the result.
  3. Call other processes that perform additional steps with that data. These steps might be by any tool you want ( TCL/TK, Python, Perl, any other script language, spreadsheet → CSV format, XSLT processor ).

Use Middleware to connect to Relational Databases

  • Use a middleware to connect to an SQL database for data storage.


Online Search Engines

Human-oriented Online Search Engines

Online Search Engines with API for Third-Party Online Applications

Free Online Services

OpenSource Servers & Tools, CMS / Wiki Plugins and Community Projects

Linked Data Browsers

OpenSource Linked Data Browsers

Free Linked Data Browsers Online Services

OpenSource Software Frameworks




LAMP / Webservice




Java, Python

PHP, Python


Link Discovery Frameworks

Link Annotation

Converters to and from RDF

Tools which learn the matching Heuristic directly from the Data



Useful Technologies and Tools

Some other Projects






Selection Criteria for Triplestore Servers

  • Support of
    • SPARQL 1.1.
    • SPARQL 1.1 Update ( SPARUL ).
    • SPARQL Protocol for RDF.
    • SPARQL Query Results XML Format”.


    • The Windows batch files work well with original COMMAND.COM of W2k, WinXP,..
    • To use the Windows batch files with 4NT command tool:
      1. Disable the “exit /b” statement at the end of the batchfiles ( e.g. put a REM in front of the statement so that its a comment, or delete the complete statement ).
      2. The last parameter of the call of the ARQ Java application, change the last parameter from ”%*” to ”%1 %2 %3 %4 %5 %6 %7 %8 %9”.

Middleware for use with an SQL Database

Triplestore Servers with SPARQL and SPARQL 1.1 Update ( SPARUL )

Triplestore Servers with SPARQL, Insert / Load of Data, but without SPARQL 1.1 Update


Free Online Services

Frameworks, Interfaces

Testing of SPARQL Vocabularies

SPIN - SPARQL Inferencing Notation



Communities & Data Providers

  • Of course everybody may create his/her own domain-specific vocabulary, but...
    • In which case is it worth to define his/her own domain-specific vocabulary?
      • Maybe if the data is not intended to be shared, e.g. just used with the own software ( egoistic approach ) :-)?!
    • What is vocabulary worth which is not recognized by other third-party software in the semantic world?

Ontology / Vocabulary

Creative Commons (CC)

Dublin Core

Europeana Data Model (EDM)

Friend of a Friend (FOAF)


Open Provenance Model Vocabulary

Semantically-Interlinked Online Communities (SIOC)

Simple Knowledge Organization System ( SKOS )


Vocabulary of Interlinked Datasets ( VoID )


Ontology / Vocabulary and Data Sources using special Ontologies / Vocabularies

Cross-Domain Data

Digital Rights


Geographic Ontology
Geographic Data
  • GeoNames - “The GeoNames geographical database covers all countries and contains over eight million placenames that are available for download free of charge”.

Media & Arts

Media & Arts Ontology
Media & Arts Data

Governmental Data


Libraries and Education

Bibliographic and Library Ontology
Libraries and Education Data

Retail and Commerce

Retail and Commerce Ontology
Retail and Commerce Data

User Generated Content and Social Media




Commercial Software

Commercial Services

Commercial Developers

  • uberblic, Berlin - “Building Great Apps with Data. We build products that aggregate data in interesting new ways. For our clients and for ourselves”.



  1. David Wood.
  2. The book-on-demand Gang Wu: "Semantic Web", ISBN 978-953-7619-54-1.

Paper Magazines, PDF Magazines, Online Magazines


Webinars, Webcasts

Reality: Search Engine Optimization by Microdata, not by RDF


Forums, Newsgroups

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