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discover

Since v1.6.0 · Used inside a declaration

Grammar​

# Flow-body form (dual of Publish-Ext):
discover <ChannelRef> as <alias>

discover is the dual of publish: it imports a previously extruded channel capability, binding the discovered handle under a local alias. Only shield-gated channels can be discovered — a channel with no shield: is not publishable, so there is nothing to import (D8: capability extrusion is shield-mediated).

Surface​

discover is nested — a flow-body / daemon-body statement.

flow Consume() -> Unit {
    discover SkillCompleted as live
}

The alias binds the shield reference of the publication in the flow's context; an undiscovered capability resolves empty (the flow observes the absence rather than crashing — totality).

Typing​

  • The channel reference must be a declared channel.
  • The channel's definition must declare a shield: (only shield-gated channels are publishable/discoverable).
  • as <alias> is required — an unbound discovery is useless.

What this primitive is NOT​

  • Not a subscription. Consuming events is listen's job; discover imports the CAPABILITY (the right to interact with the gated channel).
  • Not cross-process. Discovery resolves against the same runtime's capability context.

See also​

  • axon://primitives/publish — the extrusion this imports.
  • axon://primitives/channel — the conduit.
  • axon://primitives/listen — the event consumer.