Varve.Events 0.1.0-preview.20

Varve.Events

Domain events as quads, for systems that do not speak RDF (ADRs 0143–0145, docs/spec/events.md). A publisher writes an event as quads in an events graph, in the same commit as the change it describes. A catalogue graph declares each event type: its class, its short name, a SPARQL SELECT over the event node, and its fields. This package renders each event as a CloudEvents 1.0 event in RFC 8785 canonical JSON. It works over quads alone, with no store and no HTTP.

• EventDeclarations reads the declarations out of catalogue graphs, and says why one is not well formed. EventCatalogue names the catalogue graphs and maps one back to the source graph that governs it.
• EventCatalogueHistory replays the catalogue graphs' changes. It answers the declarations, versions and immutable schema revisions in force at any position. ContinueFrom starts the history after a dataset's declarations moved to the management plane, keeping the revisions at the move; a revision minted after it is a SchemaRevisionId written m{p} (ADR 0167).
• EventRenderer renders a commit's events. The declaration's SELECT runs over the event node's closure as of the commit, and its values are mapped to JSON by a fixed table and the number rule. Rendering a commit again yields the same bytes. An event that cannot be rendered becomes a problem event, in its place.
• EventSchemas generates each type's JSON Schema (2020-12) from its declaration when read. Golden files hold the generator's output for ever.
• EventViews writes the types list, the server-wide list and the AsyncAPI 3.0 document.
• EventDeclarationCheck decides whether a change to a declaration may commit. Its checks are well-formedness, a short name taken (refused without naming the other declaration), retirement in place of removal, and compatibility at an unchanged version.
• EventDeclarationShapes is the declaration vocabulary's SHACL shapes, as Turtle (ADR 0157). This package does not validate by them; a caller can, with Varve.Shacl. They state what SHACL Core can, and a property holds them to EventDeclarations on all of it. The SELECT, field names unique within a type, and the checks across graphs remain the code's.

Varve.Protocol serves all of it over HTTP, and its dataset validator runs the check.