A ride-hailing booking service must tell the billing and notification services about each completed trip without waiting for either to finish. Which service provides this capability?
Show answer and explanation
Answer: C
Pub/Sub is a fully managed messaging service. Publishers send events to a topic, and subscribers receive them independently and asynchronously. The booking service does not wait for billing or notifications to finish, which reduces coupling and improves resilience. Each consumer can scale and fail independently, while unacknowledged messages are retained for a configured period.
Why the other options are wrong
- A. Read replicas copy relational data to serve read traffic. They do not deliver event notifications to independent consumers that act on each trip.
- B. Object versioning keeps earlier copies of stored objects for recovery. It is not a channel that delivers events between services.
- D. Cloud VPN connects networks over encrypted tunnels. It carries traffic but does not decouple services or deliver messages to subscribers.