A few newbie questions (shapes, SPARQL, vocabularies)

svestal · January 15, 2020, 6:33pm

The core spec talks about shapes but does not mention SHACL. Is there any specific/standard relationship between OSLC shapes and SHACL, other than RDF?

The core spec talks about queries and mentions that OSLC “does not require implementers to provide … a SPARQL query-engine.” Is there any specific/standard relationship between OSLC queries and SPARQL, other than RDF?

I found one or two mentions that the standard vocabularies could/would be represented in RDF/XML with an owl:ontology element. Is there a standard place where these can be fetched?

andrew · January 16, 2020, 5:04pm

Hello Steve,

Welcome to the forum! Your questions are very much relevant.

SHACL:

There is no relation between OSLC Shapes and SHACL other than that Arthur Ryman was the key contributor to OSLC Shapes first and then to SHACL. See this publication, section 7 for a brief information of the relationship.
OSLC has to support OSLC Shapes for compat reasons.
OSLC Shapes support is in fact built on the SHACL library. SHACL shapes are supported too.

Query

Not depending on SPARQL is important to allow OSLC servers backed by SQL DBs but using RDF as an exchange format instead of JSON. SPARQL + RDF makes it very hard to still maintain an API or SQL backend.
Query is not going to be dropped or changed much, again due to compat reasons.

Ontology

The main place for their development is https://github.com/oslc-op/oslc-specs/tree/master/specs
They are published on the website, see https://open-services.net/specifications/vocabularies/. NB! There was a mishap and some of the links are wrong, see https://github.com/oslc-op/website/issues/265

ndjc · January 16, 2020, 5:34pm

I would add only that you can see more information at https://jazz.net/wiki/bin/view/LinkedData/PublishingRdfVocabularies about how OSLC recommends that RDF vocabularies are handled. That wiki also contains other best practice recommendations about RDF.

jamsden · January 16, 2020, 6:16pm

OSLC Core 3.0 Section “Resource Constraints” does indicate that servers may use other approaches to constrain resources for a particular context or purpose, including SHACL.

There is a document that describes how to map OSLC Query to SPARQL, and that was used to formalize the OSLC query semantics. See https://open-services.net/bin/view/Main/OslcSimpleQuerySemanticsV1, this may be incomplete and out of date.