Add ability to use a query or verification constraint from a central repository

[cmungall]

We can run sparql queries from robot, so individual repos can configure their own local checks, using either local sparql or sparql downloaded from somewhere else. We don't have a verify command as discussed in #24 but it's relatively easy to wrap robot to throw an error if >0 results.

It may be useful to provide a higher level abstraction over this, where we can have

• one or more repositories of rules or queries
• each rule is associated with metadata about the rule, and descriptive text
• optionally, a rule can have different ways of being implemented.

This is the idea behind the GO rule set (intended for gene associations, not ontology releases, but same idea):

https://github.com/geneontology/go-site/tree/master/metadata/rules

Many of the rules currently have SQL implementations, but @dougli1sqrd will be adding SPARQL implementations.

Here, we may want to eventually write some of these in SHACL. Even if a rule is implemented procedurally in code, it's good to document each rule and have a URI for it.

I'm not attached to the yaml-in-markdown pattern (well, I am a bit). It could be flipped around with yml being the outer shell, and descriptive text being a markdown string embedded inside.

cc @balhoff @drseb

[jamesaoverton]

Closing this in favour of #205