# 9.5: Exercises

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Exercise $$\PageIndex{1}$$

Describe in your own words what an OBDA system is. Try to keep it short, such that you can explain it in less than 30 seconds.

Exercise $$\PageIndex{2}$$

What are the principal components of the OBDA system described in some detail in this chapter?

Exercise $$\PageIndex{3}$$

How is querying in the OBDA setting different compared to plain relational database?

Exercise $$\PageIndex{4}$$

Inspect an ontology used for OBDA; e.g.,: the one of the EPnet5 or one from the Ontop examples6. Consider again Section 1.2: What is an Ontology? "The Definition Game" regarding the differences between ontologies and conceptual models and Chapter 6 on foundational ontologies. Why does the ‘ontology’ in an OBDA system look more like an OWLized conceptual data model?

Two of the reasons:

1. the ontology is specific to the application, hater than being application-independent. If it wouldn’t be, then there will be mismatches (either too much/irrelevant content in the ontology, or data that should be queried but can’t if there’s no corresponding knowledge in the ontology)
2. the ontology contains implementation decisions, such as data properties, which will hamper any reuse, be that for another application or as a module of another ontology.

Exercise $$\PageIndex{5}$$

You will set up an OBDA system. Consult the wiki at https://github.com/ontop/ontop/wiki for tutorials and sample data, and the software at https://github.com/ontop/ontop.

## Footnotes

6e.g., movies: https://github.com/ontop/ontop/wiki/..._MovieOntology

This page titled 9.5: Exercises is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by Maria Keet.