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.

Andrea

General, Reusable Metadata Ontology - V0.2

This is just a short post that a newer version of the general metadata ontology is available. The ontology was originally discussed in a blog post on April 16th. And, if you have trouble downloading the files, there is help in the blog post from Apr 17th.

I have taken all the feedback, and reworked and simplified the ontology (I hope). All the changes are documented in the ontology's changeNote.

Important sidebar: I strongly recommend using something like a changeNote to track the evolution of every ontology and model.

As noted in the Apr 16th post, most of the concepts in the ontology are taken from the Dublin Core ELements vocabulary and the SKOS data model. In this version, the well-established properties from Dublin Core and SKOS use the namespaces/IRIs from those sources (http://purl.org/dc/elements/1.1/ and http://www.w3.org/2004/02/skos/core#, respectively). Some examples are dc:contributor, dc:description and skos:prefLabel. Where the semantics are different, or more obvious names are defined (for example, creating names that provide "directions" for the skos:narrower and broader relations), then the purl.org/ninepts namespace is used.

This release is getting much closer to a "finished" ontology. All of the properties have descriptions and examples, and most have scope/usage notes. The ontology's scope note describes what is not mapped from Dublin Core and SKOS, and why.

In addition, I have added two unique properties for the ontology. One is competencyQuestions and the other is competencyQuery. The concept of competency questions was originally defined in a 1995 paper by Gruninger and Fox as "requirements that are in the form of questions that [the] ontology must be able to answer." The questions help to define the scope of the ontology, and are [should be] translated to queries to validate the ontology. These queries are captured in the metadata ontology as SPARQL queries (and the corresponding competency question is included as a comment in the query, so that it can be tracked). This is a start at test-driven development for ontologies. :-)

Please take a look at the ontology (even if you did before since it has evolved), and feel free to comment or (even better) contribute.

Andrea

Downloading the Metadata Ontology Files from GitHub

Since I posted my ontology files to GitHub, and got some emails that the downloads were corrupted, I thought that I should clarify the download process.

You are certainly free to fork the repository and get a local copy. Or, you can just download the file(s) by following these instructions:

• LEFT click on the file in the directory on GitHub
• The file is displayed with several tabs across the top. Select the Raw tab.
• The file is now displayed in your browser window as text. Save the file to your local disk using the "Save Page As ..." drop-down option, under File.

After you download the file(s), you can then load one of them into something like Protege. (It is only necessary to load one since they are all the same.) Note that there are NO classes, data or object properties defined in the ontology. There are only annotation properties that can be used on classes, data and object properties. Since I need this all to be usable in reasoning applications, I started with defining and documenting annotation properties.

I try to note this in a short comment on the ontology (but given the confusion, I should probably expand the comment). I am also working on a metadata-properties ontology which defines some of the annotation properties as data and object properties. This will allow (for example) validating dateTime values and referencing objects/individuals in relations (as opposed to using literal values). It is important to note, however, that you can only use data and object properties with individuals (and not with class or property declarations, or you end up with OWL Full with no computational guarantees/no reasoning).

Lastly, for anyone that objects to using annotation properties for mappings (for example, where I map SKOS' exactMatch in the metadata-annotations ontology), no worries ... More is coming. As a place to start, I defined exactMatch, moreGeneralThan, moreSpecificThan, ... annotation properties for documentation and human-consumption. (I have to start somewhere. :-) And, I tried to be more precise in my naming than SKOS, which names the latter two relations, "broader" and "narrower", with no indication of whether the subject or the object is more broad or more narrow. (I always get this mixed up if I am away from the spec for more than a week. :-)

I want to unequivocally state that annotation properties are totally inadequate to do anything significant. But, they are a start, and something that another tool could query and use. Separately, I am working on a more formal approach to mapping but starting with documentation is where I am.

Obviously, there is a lot more work in the pipeline. I just wish I had more time (like everyone).

In the meantime, please let me know if you have more questions about the ontologies or any of my blog entries.

Andrea

General, Reusable, Metadata Ontology

I recently created a new ontology, following the principles discussed in Ontology Summit 2014's Track A. (If you are not familiar with the Summit, please check out some of my earlier posts.) My goal was to create a small, focused, general, reusable ontology (with usage and scope information, examples of each concept, and more). I must admit that it was a lot more time-consuming than I anticipated. It definitely takes time to create the documentation, validate and spell-check it, make sure that all the possible information is present, etc., etc.

I started with something relatively easy (I thought), which was a consolidation of basic Dublin Core and SKOS concepts into an OWL 2 ontology. The work is not yet finished (I have only been playing with the definition over the last few days). The "finished" pieces are the ontology metadata/documentation (including what I didn't map and why), and several of the properties (contributor, coverage, creator, date, language, mimeType, rights and their sub-properties). The rest is all still a work-in-progress.

It has been interesting creating and dog-fooding the ontology. I can definitely say that it was updated based on my experiences in using it!

You can check out the ontology definition on github (http://purl.org/ninepts/metadata). My "master" definition is in the .ofn file (OWL functional syntax), and I used Protege to generate a Turtle encoding from it. My goals are to maintain the master definition in a version-control-friendly format (ofn), and also providing a somewhat human-readable format (ttl). I also want to experiment with different natural language renderings that are more readable than Turtle (but I am getting ahead of myself).

I would appreciate feedback on this metadata work, and suggestions for other reusable ontologies (that would help to support industry and refine the development methodology). Some of the ontologies that I am contemplating are ontologies for collections, events (evaluating and bringing together concepts from several, existing event ontologies), actors, actions, policies, and a few others.

Please let me know what you think.

Andrea