Digital Objects

To provide the customer with information on the possibilities of 3TU.Datacentrum, it's important to understand how the 3TU.Databrowser works. Therefore, we will first have a look at digital objects. What are they?
 
An object is a "thing". Every thing has a sort (object-type). Within 3TU.Datacentrum the following object-types are present and discerned:

  1. dataset
  2. location
  3. time frame
  4. measuring instrument
  5. collection
  6. study
  7. document (documentation belonging to datasets or collections)
  8. image (at this moment only present as an independent object-type once in 3TU.Datacentrum. Images may also be part of datasets)

Some objects are related. A dataset can be a member of a collection and measured by a device. The device itself can be located in a certain geographical location.

For example:

                             Image by Jeroen Rombouts & Egbert Gramsbergen

Relations

Relations between digital objects are described in RDF (Resource Description Framework). RDF is a standard from the World Wide Web Consortium (W3C). It's a data model: a structured way in which data structures in an information system are described in order for different applications to be able to use the data. RDF is designed to make information machine readable. 

How does RDF work? For every thing a URI is used. A URI is a Uniform Resource Identifier which defines the location of a source and the way it can be approached and reached. A URI often is a URL. Subsequently every thing is linked to other things via so called RDF triples. An RDF triple states: thing x has relationship y with thing z. This way of establishing relationships is called linked data1. The web on which you can access these linked data is called the semantic web, the web of relations. It's not only the things (digital objects) which get a URI; the relationship between the things also gets a URI. This is an example of a URI: 

http://purl.org/dc/terms/created

This is a URI stating that thing x was created by thing y. dc stands for Dublin Core. Use had been made from standard vocabulary. But 3TU.Datacentrum also has its own URIs, like: 

http://www.library.tudelft.nl/ns/rdf/measuredBy

The above relationship states that thing x was measured by thing y (thing y being a measuring instrument). This relationship wasn't available within the Dublin Core RDF repertoire, so it was created by 3TU.Datacentrum. Homemade URIs are subsequently coupled with existing URIs to enabling a user to trace its meaning. 

By capturing digital objects as linked data, enhanced publications are made possible, enhanced publications are made possible. 

Want to know more about linked data?

  1. Linked data stap voor stap2 (Dutch)
  2. Linked data book3

 

1. Angevaare, I. (2011, january 17th). Linked Data. Wat is dat nu eigenlijk? Retrieved 9-12-2011 from digitaalduurzaam.blogspot.com/2011/01/linked-data-wat-is-dat-nu-eigenlijk.html
2. DEN (Kenniscentrum digitaal erfgoed). (2011). Linked data stap voor stap. [tutorial]. Retrieved 9-12-2011 from http://www.den.nl/pagina/334/den-lab/
3. Heath, T., Bizer, C. (2011). Linked Data: Evolving the web into a global data space. Morgan & Claypool. Retrieved online 9-12-2011 from http://linkeddatabook.com/editions/1.0/

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