Chapter Assessment: Events and Messaging

This review covers events and messaging in the booking service. Its subjects are application events inside one process, listeners that wait for the commit, Kafka topics and consumer groups, the transactional outbox with its relay, and consumers that handle the same message twice safely. The bank holds 20 questions, and each attempt draws ten. Most questions describe a failure, such as an email for a booking that rolled back, a broker outage, or a relay that stops halfway, and ask what happens next or which fix fits