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QUERY_EXECUTION.md

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Query Execution

Janus routes a registered query according to its declared windows.

Lifecycle

  1. POST /api/queries parses and validates Janus-QL, then stores query metadata.
  2. POST /api/queries/:id/start starts the applicable historical and/or live execution path and creates the result forwarder for WebSocket subscribers.
  3. GET /api/queries/:id/results upgrades to a WebSocket and emits JSON result messages with a query id, timestamp, source, and bindings.
  4. POST /api/queries/:id/stop stops an active query; only stopped queries can be deleted.

Execution paths

  • A historical fixed window is lowered to a SPARQL query over segmented storage and emits Historical results.
  • A live window is lowered to the live RSP-QL path and consumes its MQTT-backed stream source, emitting Live results.
  • A hybrid query creates both paths. Historical materialization is prepared for supported nested historical subqueries before it is made available to the live path.

Status

Query metadata exposes Registered, WarmingBaseline, Running, Stopped, or Failed(...). WarmingBaseline is implementation compatibility behavior; it should not be used as a public Janus-QL language feature.

See HTTP API for the transport contract and Nested Historical Subqueries for lowering constraints.