Engine

Engine is the top-level coordinator: it owns every bus, subsystem and exchange connector, starts them in the correct order, and stops them on shutdown.

```cpp class Engine { public: Engine(const EngineConfig& cfg, std::vector buses, std::vector subsystems, std::vector> connectors);

void start(); // initialise & run all components void stop(); // graceful shutdown }; ````

Related Type

Struct	Purpose
ExchangeInstance	Bundles connector metadata (exchangeType, name, symbol) with the concrete ExchangeConnector pointer.

Purpose

• Centralise ownership of every runtime component.
• Guarantee deterministic startup / shutdown sequencing.
• Keep strong separation between infrastructure (buses, subsystems) and external I/O (connectors).

Responsibilities

Phase	Action
start	1) Start buses → 2) start subsystems → 3) start connectors.
stop	Reverse order: connectors → subsystems → buses.
State	Store the immutable EngineConfig and vectors of injected components.

Notes

• Fulfils concepts::Engine, so it can be referenced anywhere a generic Subsystem is expected.
• Construction is dependency-injected: the builder outside the class instantiates buses/subsystems/connectors and passes them in, enabling test harnesses or alternative compositions.