ObjectEvent

An ObjectEvent is a type of event used in software systems to convey information about a change or action related to a specific object instance. It is commonly employed in event-driven architectures, domain-driven design, and auditing to decouple the producer of information from its consumers.

An ObjectEvent typically includes identifying information about the subject object, the kind of change, a timestamp, and optional payload data describing the details of the event. Core fields often include object_id or object_reference, event_type, timestamp, and payload. Some designs also capture previous_state or new_state to indicate a state transition.

In practice, ObjectEvent can be emitted by domain objects, services, or event buses. It may publish domain events to observers, update caches, populate an event store, or drive downstream workflows. Examples include a User object emitting an event with type "UserCreated", object_id "u123", a timestamp, and payload such as {name: "Alice"}; or a BankAccount emitting "MoneyDeposited" with amount and the resulting balance.

Implementation considerations include whether ObjectEvent is a concrete type or a generic wrapper, how to enforce typing, how to serialize payloads, and how to manage object references to avoid memory leaks or privacy concerns. In event-sourced or distributed systems, ObjectEvent may be stored in an event store or delivered through an event bus, influencing design choices around durability and latency.

Related concepts include domain events, event-driven architecture, event sourcing, observers, and audit logging.