Implementing Domain-Driven Design

With Aggregate Characteristics

Sometimes Events are designed to be created by direct request from clients. This is done in response to some occurrence that is not the direct result of executing behavior on an instance of an Aggregate in the model. Possibly a user of the system initiates some action that is considered an Event in its own right. When that happens, the Event can be modeled as an Aggregate and retained in its own Repository. Since it represents some past occurrence, its Repository would not permit its removal.

When Events are modeled in this way, like Aggregates they become part of the model’s structure. Thus, they are not just a record of some past occurrence, although they are that also.

The Event is still designed as immutable, ...