Skip to content

component-model.md

Latest commit

 

History

History
90 lines (63 loc) · 2.82 KB

component-model.md

File metadata and controls

90 lines (63 loc) · 2.82 KB
Raw

Component Model

The component model defines how user algorithm modules plug into PuppetMaster. It builds on the previous runtime context work: components declare their endpoints and triggers, then the runtime drives a small lifecycle around that declaration.

Design Goal

The interface is intentionally narrow:

  • ComponentSpec describes what a module needs
  • Component implements the algorithm module
  • ComponentContext gives the module access to runtime services
  • RuntimeContext owns registration and lifecycle state

Transport details stay behind Reader, Writer, and Transport. Scheduler details stay out of the component interface for now.

ComponentSpec

ComponentSpec remains the declarative part of a module:

  • component name
  • description
  • reader endpoints
  • writer endpoints
  • trigger specs

This lets the runtime inspect a component before it starts executing. The scheduler can later use the same spec to wire periodic, data-driven, dependency, or manual triggers.

Component

Component is the runtime-facing base class for algorithm modules:

class MyAlgorithm final : public puppet_master::runtime::Component {
public:
    puppet_master::runtime::ComponentSpec Describe() const override;

    puppet_master::core::Status Configure(
        puppet_master::runtime::ComponentContext& context) override;

    puppet_master::core::Status Execute(
        puppet_master::runtime::ComponentContext& context) override;
};

The lifecycle is explicit:

created -> configured -> initialized -> started -> stopped -> shutdown

Execute() is only valid after the component has started. A failed lifecycle callback moves the component to error.

ComponentContext

ComponentContext is passed into lifecycle callbacks. It lets a module create readers and writers from its declared endpoints:

auto writer = context.CreateWriter(spec_.writers.front());
auto reader = context.CreateReader(spec_.readers.front());

This keeps algorithm code independent from concrete transports. The same module can use in-memory transport in tests and a DDS-backed transport later, as long as the endpoint spec selects the desired backend.

Runtime Ownership

RuntimeContext::RegisterComponent(ComponentPtr) stores both:

  • the component declaration returned by Describe()
  • the component instance and its current state

The older RegisterComponent(ComponentSpec) path still exists for pure declarative registration, but lifecycle operations require a real component instance.

What This Milestone Does Not Do

The scheduler layer builds on this model by reading registered component specs, observing their triggers, and calling ExecuteComponent() when a component becomes ready. Component code still only implements lifecycle callbacks and Execute(); it does not need to know which scheduler policy triggered it.