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Frequently Asked Questions
Do you have Questions for Synchronous API vs Event-Driven Integration: How to Choose the Right Pattern ?
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Synchronous API integration requires a caller to wait for an immediate, authoritative response before proceeding, while event-driven integration publishes facts about committed state changes asynchronously, allowing independent consumers to react without blocking the producer.
Decide based on the interaction's response timing, consistency boundary, failure handling, observability, and ownership. Use synchronous APIs when an immediate decision or confirmation is required; choose asynchronous events when multiple consumers can react on their own timelines without affecting the producer.
Yes, hybrid patterns are practical. For example, immediate commands can be handled synchronously to meet user expectations, while durable state-change events are published asynchronously to inform downstream consumers and systems.
Implement clear timeouts, define retry policies with idempotency keys to avoid duplicate processing, handle dependency failures with fallbacks or circuit breakers, and provide status endpoints or callbacks for uncertain outcomes.
You must assign named owners for event contracts, platform or broker management, each consumer's retry and idempotency handling, alerting and on-call response, replay approval, data reconciliation, and incident management.
Idempotency ensures retry safety by allowing repeated processing of the same request or event without unintended side effects, preventing issues such as double payments, duplicate reservations, or repeated notifications.
HTTP 202 Accepted indicates that a request was received but not yet fully processed. Use it to signal asynchronous acceptance in synchronous APIs, combined with status endpoints or events to notify final outcomes asynchronously.
Event-driven integration decouples producers and multiple independent consumers by broadcasting facts once, enabling consumers to evolve independently, handle bursty load via buffers, and replay events for recovery without blocking producers.
Maintain a tight consistency boundary in synchronous commands for immediate decisions, publish durable events after authoritative commits, use transactional outbox patterns to link DB writes with event publishing, and establish clear replay and recovery policies.
Use correlation IDs and distributed tracing for end-to-end visibility, monitor latency and error rates for synchronous APIs, track consumer lag and delivery status for events, and surface delivered versus fully processed business outcomes clearly.
Synchronous APIs are not ideal when the operation involves long chains of dependencies that don't require immediate answers, increasing latency and fragility. In such cases, pre-computation, caching, or event-driven flows better serve business value.
