Engine & Primitives

The concepts here are the heart of Cloacina, independent of how you run it. They apply whether you embed the library or run the service — each object is described once, with both its Rust and Python interfaces.

Who this is for: anyone learning the engine primitives — workflows, computation graphs, scheduling, and packaging — regardless of language. This material is language-agnostic.

Prerequisites: basic familiarity with the concepts from Start Here.

The core primitives:

• Workflow — a durable, database-backed DAG; the task is the unit of scheduling.

• Task — a unit of work in a workflow.

• Context — typed data passed between tasks, persisted and recovered.

• Computation Graph — an in-process, event-driven dataflow; the whole traversal is the unit.

• Node — a vertex in a computation graph.

• Reactor — binds accumulators to a graph and fires it when criteria are met.

• Accumulator — turns a source or stream into boundary events (passthrough, stream, polling, batch, state).

• Boundary event — the typed event an accumulator emits and a reactor reacts to.

• Trigger — fires a workflow (poll or cron).

• Cron schedule — time-based workflow scheduling.

• Package (.cloacina) — the distributable unit.

• Runner — the host that executes workflows against a database.

• Workflows

  • Workflow
  • Task
  • Context
  • Runner
  • How-to Guides
    • Build Workflows with WorkflowBuilder
    • Use Secrets in a Workflow

• Computation Graphs

  • Computation Graph
  • Node
  • Reactor
  • Accumulator
  • Boundary event
  • How-to Guides
    • Package a Python Computation Graph
    • Choosing and Using Accumulator Types
    • Filter Reactor Subscriptions (Python)
    • Monitoring Computation Graph Health
    • Manually Driving Graph Surfaces
    • Computation Graph in a Workflow Task
    • Triggering Workflows from Reactor Firings
    • Using when_all Reaction Criteria
    • Filter reactor firings with CEL
    • Using Sequential Input Strategy

• Scheduling & Triggers

  • Workflow Instances
  • Trigger
  • Cron schedule

• Packaging

  • Package

• Constructors & Providers

  • Author a Constructor Provider
  • Consume a Constructor Provider
  • Capability Grants
  • Seed Providers

• Explanation

  • Architecture Overview
  • Workflow Versioning
  • Context System
  • Trigger Rules
  • Macro System
  • Computation Graph Architecture
  • Python CG Decorator Surface
  • Accumulator Design
  • Inventory and Runtime Seeding
  • Package Format
  • FFI System
  • Packaged Workflow Architecture
  • Guaranteed Cron Scheduling
  • Reactor Lifecycle
  • Trigger-less Computation Graphs
  • Packaging & FFI
  • Task Execution
  • Task Deferral
  • Dispatcher Architecture
  • Graph Scheduling
  • Performance Characteristics
  • Subscription fan-out
  • Cron Scheduling Architecture