Integration Events
An Integration Event is a message that informs components outside of the source Bounded Context that something of significance has happened. An Integration Event does NOT lead to any state changes in the source Bounded Context.
Are different from targeted consumer perspective. Integration event consumers are outside the source Bounded Context.
From content and handling perspective, they are no different than the domain events
Asynchronous communication is preferred:
- To achieve HIGHER levels of decoupling
- Future extensibility i.e., add new consumers
- Enables one-to-many
Domain/Integration event similarities
- Both events defined as part of the model for the BC
- Semantically same
Example
In this illustration:
- Personal loan microservice produces events Application Receieved
- The Domain event is consumed by the producing microservice
- The Integration event Application Received is consumed by Complian microservice
- The Integration event Loan Account Established is consumed by Notification service
Domain vs Integration Events
| Domain | Integration |
|---|---|
| Within a BC or Microservice | Between BC |
| State changes in BC | NO state change in source BC |
| Direct function calls | Must be a Network protocol |
| Synchronous calls | Asynchronous preferred |
| Modeled as part of BC model | Consumer uses Tactical pattern |