Java EE 8 Design Patterns and Best Practices

Understanding the event of event sourcing 

In the event sourcing pattern, an event is considered an update that will be applied to the data. When a user requests a data update, the application will not update it in real-time but will instead get the data, create an imperative description of an update, and save the event with that description. This event is then saved in the event repository. Note that the consumer of an event can be another application or resource. 

Using the event sourcing pattern, the end user is able to see older versions of data because the data is only updated when the event is saved on the event repository and running. With this in mind, the end user will not see the update in real-time, as the update is scheduled and ...