Non-functional requirements

Non-functional requirements are the ones that decide whether an architecture works at the size and reliability the business needs, and they are the ones most often written as adjectives — “highly available”, “scalable”, “real time” — when they need to be numbers.

This section holds the reference material for turning those adjectives into figures.

AWS integration pattern comparison matrix is the canonical home for the quotas that decide between a REST API, EventBridge, SQS and Kinesis: throughput, payload size, latency, delivery guarantee and cost, with the Regional variation that catches designs validated in one Region and deployed in another.

Multi-account landing zone with redundant connectivity sets out a reference account and connectivity structure, and then does the availability arithmetic that a target like five nines actually implies — which is usually the conversation that needs having before the diagram is drawn.

Availability targets themselves are defined in high availability and disaster recovery concepts.