A fallback is a fault-tolerance pattern that supplies an alternative operation when the primary operation fails. In Quarkus, MicroProfile Fault Tolerance applies it declaratively with annotations, keeping resilience logic separate from business code. section 10.5
Fallbacks are applied where failures are observed: the calling service, not necessarily the service being called. A fallback can follow retries, returning a safe result when attempts are exhausted. section 10.5.1
Car-rental availability
The Reservation service calls Inventory for available cars. It retries the availability operation up to 25 times with a one-second delay; if Inventory remains unavailable, @Fallback(fallbackMethod = "availabilityFallback") returns an empty list through availabilityFallback. section 10.5.1
Listing 10.8 Fault tolerance availability fallback
public Uni<Collection<Car>> availabilityFallback(LocalDate startDate,
LocalDate endDate) {
return Uni.createFrom().item(List.of());
}
Shows the fallback method that returns an empty collection when availability cannot be obtained. section 10.5.1
