Vocabulary Implementation Requirements
The following vocabulary requirements complement those in the core xAPI specification and have been expanded to reflect the new responsibilities of creating and publishing xAPI vocabularies as linked datasets.
| Requirement Number | Description | Conformance Level |
|---|---|---|
| 1 | Anyone establishing new vocabulary datasets or vocabulary terms SHOULD first check xAPI community resources (e.g., registries, repositories) to see if existing terms already exist to avoid duplication. | SHOULD |
| 2 | Anyone establishing new vocabularies and new vocabulary terms for xAPI MUST use HTTP IRIs so that they can be resolved/dereferenced. | MUST |
| 3 | Anyone establishing new vocabularies SHOULD use persistent and well-designed IRIs so that they can be stable for long term reliability. See the IRI Design and Persistence Section of this document for guidelines. | SHOULD |
| 4 | Anyone creating new vocabulary terms MUST provide descriptive metadata by minimally using the recommended classes and properties in this specification, and associate the terms with a vocabulary (concept scheme). | MUST |
| 5 | Vocabulary datasets SHOULD contain additional provenance metadata about the authors, version, date created, and date last modified. | SHOULD |
| 6 | Authors MAY also express relationships between terms using SKOS. | MAY |
| 7 | Anyone establishing a new vocabulary MUST publish a human-readable representation of the vocabulary dataset as HTML accessible at the IRI. | MUST |
| 8 | Anyone establishing a new vocabulary MUST publish at least one additional machine-readable representations of the vocabulary dataset in RDF (e.g., RDFa,JSON-LD,Turtle). | MUST |
| 9 | If multiple representations exist, vocabulary authors SHOULD provide a means of discovering each of the available dataset representations through content negotiation. | SHOULD |
| 10 | Anyone publishing a vocabulary dataset SHOULD announce the availability of the vocabulary and submit it to xAPI community resources (e.g., registries, repositories). | SHOULD |
| 11 | Repositories, registries, or any other systems that publish xAPI vocabulary datasets expressed as RDF SHOULD provide a public SPARQL endpoint for querying that data. | SHOULD |
| 12 | Since vocabularies can change, a system aggregating vocabularies SHOULD have a process to keep their versions up to date. | SHOULD |
Figure 9. Table of xAPI vocabulary requirements.