Assume that two customers are simultaneously attempting to book tickets for the same flight, which has limited seat availability. How does the design pattern for limited availability and concurrency handle this scenario? (Choose Two)
A.
The design pattern records booking attempts for both customers. If the flight exceeds capacity, the customer goes on a waiting list. The waiting list clears after a certain period, and the customer receives notification of the results.
B.
The design pattern rejects both bookings, entering an ambiguity mode. It prompts customers to try again later. In the second attempt, it prioritizes one customer based on a first-come-first-serve basis.
C.
The design pattern allows both customers to book; however, one receives a notification about no available seats after the analysis.
D.
The design pattern prioritizes customer bookings on a first-come-first-serve basis.
Comprehensive and Detailed Explanation From Exact Extract:
Pega’s limited availability and concurrency design pattern, as taught in Pega Academy’sApplication Design Missionand thePega Certified Lead System Architect Study Guide, relies on locking mechanisms to manage resource contention, such as booking limited flight seats. It ensures fair and consistent handling of concurrent requests.
Option A (Incorrect): Recording attempts and placing customers on a waiting list is a business process, not a core feature of the concurrency design pattern.The pattern focuses on locking and allocation, not waitlist management, per theConcurrency Designmodule.
Option B (Incorrect): Rejecting both bookings and entering an ambiguity mode is not a standard Pega approach. The platform uses locking to resolve concurrency, not ambiguous retries, as noted in theLocking Mechanismsguidelines.
Option C (Correct): The design pattern allows both customers to attempt booking, but Pega’s locking (e.g., pessimistic locking) ensures only one secures the seat. The other receives a notification of no available seats after the system checks availability, aligning with Pega’s concurrency handling, as documented in theLimited Availability Patternsection of Pega Community.
Option D (Correct): The pattern often prioritizes bookings on a first-come-first-serve basis, with the first request to lock the resource (e.g., seat) succeeding. This is managed by Pega’s locking mechanism, per theConcurrency Designmodule.
[:, Pega Academy:Application Design Mission(covers concurrency and limited availability)., Pega Community:Locking MechanismsandLimited Availability Pattern(details on booking scenarios)., Pega Certified Lead System Architect Study Guide (v23): Section onApplication Design(emphasizes locking for concurrency)., ]
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