Salesforce Exam Integration-Architecture-Designer Topic 2 Question 28 Discussion

Northern Trail Outfitters has a registration system that is used for workshops offered at its conferences. Attendees use a Salesforce community to register for workshops, but the scheduling system manages workshop availability based on room capacity. It is expected that there will be a big surge of requests for workshop reservations when the conference schedule goes live.

Which integration pattern should be used to manage the influx in registrations?