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Event Sourcing

What is the “Event Sourcing” design pattern?

  • “Event Sourcing” persists the state of a business entity as a sequence of state-changing events.
  • Whenever the state of a business entity changes, a new event is appended to the list of events (to the log).
  • The application reconstructs current state of the entity by replaying the events.

What are the benefits and drawbacks of the “Event Sourcing” microservices design pattern?

The benefits of the “Event Sourcing” pattern

The drawbacks of the “Event Sourcing” pattern

When to use “Event Sourcing” design pattern?

Use this pattern in the following scenarios:

  • When you want to capture intent, purpose, or reason of change in the data. For example, changes to a customer entity can be captured as a series of specific event types, such as Subscribed, Changed Address, Closed Account, Activated, or Deactivated.
  • When it is important to minimize or completely avoid the occurrence of conflicting updates to data.
  • When you need to audit data changes, including additional attributes such as “updateTimestamp”, “ubdatedBy”
  • When you need to to implement additional workflow such as “changeApprovedBy” and rollback if disapproved
  • When you want to record events that occur, to replay them to restore the state of a system, to roll back changes, or to keep a history and audit log.


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