ISubscriber

ISubscriber defines the minimal interface for any component that consumes events via EventBus. It provides a stable identity for routing.

using SubscriberId = uint64_t;

struct ISubscriber
{
  virtual SubscriberId id() const = 0;
};

Purpose

• Abstract base for all event consumers, enabling uniform routing and identification.

Responsibilities

Method	Description
id()	Returns a globally unique ID for this subscriber.

Notes

• SubscriberId is typically derived from pointer identity or hash — no strong ownership implied.
• Uniqueness is required and nothing verifies it. Two subscribers sharing an id collide wherever the id is used as a key. For Strategy that includes order ids, which are numbered within each strategy and prefixed with the subscriber id, so two strategies built with the same id emit orders the executor and the order tracker cannot tell apart.
• Used by EventBus<T> to track subscribers and apply fan-out policy.
• Derived interfaces like IMarketDataSubscriber and IOrderExecutionListener extend this base.