Handling of BrewChamberEmpty messages

This is a special scenario for handling the BrewChamberEmpty messages. On the coffee machine, a BrewChamberEmpty error will pop up on the screen, indicating to the user that something may have gone wrong with the last product and that it could potentially have been caused by an empty bean hopper.

The D2D RAPI reports all products as unavailable while the BrewChamberEmpty message is active in the status list on the UI. This should help a remote client to not accidentally order a coffee product while the bean hopper is potentially empty. Just as on the UI however the D2D RAPI will still accept and confirm any request to produce a coffee product while BrewChamberEmpty is active.

@startuml actor User participant "Remote Controller" as remote participant "Coffee Machine" as cm remote -> cm: Request StartProduct cm -> remote: Response StartProduct ok cm -> remote: Event BrewChamberEmpty(errno=35) note right While pouring the product, the coffee machine detected that the brew chamber is empty and thus aborts pouring of the product. end note cm -> remote: Event ProductFinished(success=false) cm -> remote: ProductAvailability (no product available) group BrewChamberEmpty still active remote -> cm: Request StartProduct cm -> remote: Response StartProduct ok cm -> remote: Event BrewChamberEmpty end note right Products can still be dispensed. On the coffee machine, the BrewChamberEmpty does not block the coffee products, it just changes the ProductAvailability-List. end note User -> cm: confirm the BrewChamberEmpty error on UI note right A user, for example a service technician, checks the machine and refills the bean hopper if necessary. Then they confirm the message in the status list on the UI. end note cm -> remote: ProductAvailability (previous list) note right Products will be listed as available again, however when milk is still missing or too warm, only non-milk products become available. end note note over remote, cm #FFAAAA The coffee machine does not send any messages to confirm the BrewChamberEmpty via the Remote API when the BrewChamberEmpty error is confirmed in the UI. end note @enduml