Concepts
Steps exchange named Attributes, and Flows use those relationships to reach their Goals.
- Steps describe the work Argyll can perform.
- Spaces scope planning to a labelled subset of the catalog.
- Attributes carry values between producers and consumers.
- Flows plan and track one execution toward a set of Goals.
- Architecture explains the cluster, state stores, and service boundary.
- Event Sourcing explains durable execution and recovery.
Terms
- Upstream / downstream: an upstream Step produces a value consumed by a downstream Step.
- Fan-out / fan-in: fan-out creates Work Items from input values; fan-in collects their results.
- Idempotent: repeated requests produce one external effect. HTTP Steps receive a receipt token for this purpose.
- Terminal: a Flow has reached
completedorfailed. - Deactivated: a terminal Flow has settled all active and compensating work.
- Selector: the label match that decides which Steps a Space contains.
Steps
A Step declares one unit of work, the Attributes it consumes, and the Attributes it produces.
Spaces
A Space is a live selection over the Step catalog, and planning inside it considers only the Steps it selects.
Architecture
Argyll combines Raft consensus with event-sourced state so every node follows the same committed execution history.
Event Sourcing
Committed events provide durable Flow state, recovery, and an inspectable execution history.