Example Step 9: Link the data

A final and optional step is to link the data to other datasets to provide more context to the data. Different types of links can be made: ontology links and data links. The data is already linked to a vocabulary, in this case to our own energy ontology, i.e., each object has a type. This ontology can be linked to other, better known ontologies. For example, our ontology talks about addresses, postcodes and units of measure, some concepts that have been described elsewhere. Addresses and postcodes, for example, appear in the W3C Location vocabulary . Such links can be specified usingsubClassOf orequivalentClass relations in the energy ontology itself, or in a separate mapping ontology that imports the energy ontology and the ontologies we map to. Such mappings can be exploited by a reasoner attached to the triple store to derive additional links between the data and the more general ontologies. In this way, a user that does not know the energy ontology can query the dataset using the more general ontologies. For example, we could assert that a UsageArea is a Location according to the W3C Location vocabulary as follows:

 energy:UsageArea rdfs:subClassOf dcterms:Location. 

The data itself can also be linked to other available linked datasets. This may be useful to provide more context to the data. Consider for example the addresses in our dataset. They contain a reference to a town. It is likely that more information about these towns is already available on the web. DBpedia, for example, the linked data version of Wikipedia, usually has an entry for each town. We could add triples to our dataset to link our Usage Areas to the DBpedia entry providing more information about the town in which the Usage Area lies. The link from a Usage Area to the DBpedia entry for the city could be made as follows:

<http://data.liander.nl/id/UsageArea/1012CM1012CN>
      dbpedia-owl:isPartOf dbpedia:Amsterdam 

This is just one triple relating a specific Usage Area to the DBpedia entry for Amsterdam. Of course, it is impractical to add such links by hand because our dataset contains tens of thousands of Usage Areas. A semantic link tool, such as SiLK, is useful to semi-automate the linking of data .

Go back to example overview

Een gegevensverzameling is een verzameling RDF-triples, die wordt gepubliceerd, onderhouden of geaggregeerd door één aanbieder.

Weergave van een feit, begrip of aanwijzing, geschikt voor overdracht, interpretatie of verwerking door een persoon of apparaat

Formele definitie van de klassen, eigenschappen en relaties van een datastructuur en de bijbehorende constraints als een knowledge graph

DBpedia is a crowd-sourced community effort to extract structured information from Wikipedia and make this information available on the Web. DBpedia allows you to ask sophisticated queries against Wikipedia, and to link the different data sets on the Web to Wikipedia data. We hope that this work will make it easier for the huge amount of information in Wikipedia to be used in some new interesting ways. Furthermore, it might inspire new mechanisms for navigating, linking, and improving the encyclopedia itself.