AWS Lambda and Serverless Function Patterns#

Lambda runs your code without you provisioning or managing servers. You upload a function, configure a trigger, and AWS handles scaling, patching, and availability. The execution model is simple: an event arrives, Lambda invokes your handler, your handler returns a response. Everything in between – concurrency, retries, scaling from zero to thousands of instances – is managed for you.

That simplicity hides real complexity. Cold starts, timeout limits, memory-to-CPU coupling, VPC attachment latency, and event source mapping behavior all require deliberate design. This article covers the patterns that matter in practice.

Event-Driven Architecture for Microservices#

In a microservices architecture, services need to communicate. The two fundamental approaches are synchronous (request-response) and asynchronous (event-driven). Most systems use both – the decision is which interactions should be synchronous and which should be event-driven.

Synchronous vs Asynchronous Communication#

Synchronous (request-response): Service A calls Service B and waits for a response. Simple, familiar, and works well when A needs the response to continue. The cost is temporal coupling – if B is down, A fails.