ADR-9: Extract notification service
Proposed
Provide customer and expert notification capability to all domain areas.
The service does not belong to any specific domain and is used by all domain services.
If notifications arrive a bit late to the destination due to maintenance or failure, this is not critical to the business operations, thus it does not require any specific considerations towards availability and performance.
Alternative would be having a separate notification service for each domain, but this will require to duplicate implementation in several places what will negatively impact on maintainability.