GuideTechnology
17 min read
Design a notification platform that other services use to reach users by push, SMS, email and in-app inbox: requirements and estimates, a 202-accepted API with idempotency keys, preferences and templates, priority queues per channel, provider rate limits and failover, retries and dead-letter queues, deduplication, delivery tracking, campaign fan-out, failures, security and observability.
GuideTechnology
17 min read
Retries are necessary in distributed systems, and they create duplicates. Learn what idempotency means, where duplicates come from, how to build idempotency keys correctly, unique constraints and idempotent consumers, which errors to retry, exponential backoff with jitter, retry amplification, and what at-most-once, at-least-once and effectively-once delivery really promise.
GuideTechnology
18 min read
Why queues exist and how they work: producers, consumers and brokers, acknowledgements and redelivery, visibility timeouts, retries, dead-letter queues, ordering, and delivery guarantees. Compares work queues, pub/sub and event streams such as Kafka, and shows how to design background workers that are safe to run twice.
GuideTechnology
17 min read
When should a caller wait for an answer, and when should work happen later? Learn the costs and benefits of synchronous calls and asynchronous processing, the patterns for returning results later (202 and status polling, webhooks, push), and how to choose between short polling, long polling, Server-Sent Events, WebSockets and mobile push.
