Creating an event store
Before we get to the scoping phase of creating an event store, it is important for us to fully understand what one is. A simple search on the topic might yield many results from various sources, with each citing varied definitions. For this book, we will conclude that an event store is an ordered, easily queryable, and persistent source of long-term records that represents events that have happened against entities in a data store.
In exploring the implementation of a data store, let us break out the key parts and how they connect to give the resulting event store. An event record will have an aggregate ID, a timestamp, an EventType flag, and data representing the state at that point in time. An application will persist event records in a data store. This data store has an API or some form of interface that allows for adding and retrieving events for an entity or aggregate. The event store might also behave like a message broker allowing for other services...
