Wednesday, May 7, 2014

Updated metadata ontology file (V0.6.0) and new metadata-properties ontology (V0.2.0) on GitHub

I've spent some time doing more work on the general metadata ontologies (metadata-annotations and metadata-properties). Metadata-annotations is now at version 0.6.0. In this release, I mainly corrected the SPARQL queries that were defined as the competency queries. SPARQL is straightforward, but it is easy to make mistakes. I made a few in my previous version (because I just wrote the queries by hand, without testing them - my bad). Anyway, that is all fixed now and the queries are correct. My apologies on the errors.

You can also see that there is a new addition to the metadata directory with the metdata-properties ontology. Metadata-properties takes some of the concepts from metadata-annotations, and redefines them as data and object properties. In addition, a few supporting classes are defined (specifically, Actor and Modification), where required to fully specify the semantics.

Actor is used as the subject of the object properties, contributedTo and created. Modification is designed to collect all the information related to a change or update to an individual. This is important when one wants to track the specifics of each change as a set of related data. This may not be important - for example, if one only wants to track the date of last modification or only track a description of each change. In these cases, the data property, dateLastModified, or the annotation property, changeNote, can be the predicate of a triple involving the updated individual directly.

It is important to understand that only a minimum amount of information is provided for Actor and Modification. They are defined, but are purposefully underspecified to allow application- or domain-specific details to be provided in another ontology. (In which case, the IRIs of the corresponding classes in the other ontology would be related to Actor and Modification using an owl:equivalentClass axiom. This was discussed in the post on modular ontologies, and tying together the pieces.)

Also in the metadata-properties ontology, an identifier property is defined. It is similar to the identifier property from Dublin Core, but is not equivalent since the metadata-properties' identifier is defined as a functional data property. (The Dublin Core property is "officially" defined as an annotation property.)

To download the files, there is information in the blog post from Apr 17th.

Please let me know if you have any feedback or issues.


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