Assignment task: Consider a system that includes a database client and two redundant database servers. Both database servers are identical: the first acts as a main server, the second acts as a hot backup in case the main server fails. The database client accesses the servers through a single component called a gateway, hence hiding from the client which server is currently being used. A separate policy object called a watchdog monitors the requests and responses of the main server and, depending on the responses, tells the gateway whether to switch over to the backup server. What security design pattern(s) can be used to best describe this system architecture scenario? Detailed answer please.