Serverless Refactoring And Modernization — AWS Solutions Architect (SAA-C03)
Serverless modernization requires matching trigger to event source
Architecture requirement: replace a polling or scheduled batch process with a genuinely event-driven serverless pattern. Competing choices: Lambda with EventBridge schedule, Lambda with SQS trigger, Lambda with S3 event notification, or Fargate scheduled task. Deciding constraint: what produces the event — a time schedule, a queue depth, a storage write, or an API call? Lambda's execution model is defined by its trigger. A scheduled Lambda running every minute is a cron job in serverless clothing. The exam tests event-driven design, not serverless syntax.
What This Pattern Tests
The exam describes a workload and tests whether serverless is the right modernization path. Lambda works for event-driven, short-duration workloads (API handlers, file processors, stream consumers). It fails for long-running processes (>15 min), workloads needing persistent connections (WebSockets need API Gateway WebSocket APIs), or high-throughput steady-state (Lambda per-invocation cost exceeds Fargate at ~1M requests/day). Lambda in a VPC adds cold start latency (VPC ENI creation) unless you use provisioned concurrency ($$$). Step Functions orchestrate multi-step workflows that exceed Lambda timeout. The trap is assuming Lambda is always the modernization answer.
Decision Axis
Workload duration, traffic pattern, and connection requirements determine whether serverless fits or a container is cheaper and simpler.
Associated Traps
More Top Traps on This Exam
Decision Rules
Select the compute refactoring target that satisfies both the long-running duration constraint (>15 minutes) and the loose-coupling, reduced-overhead modernization goal — forcing elimination of Lambda on duration grounds and EC2 Auto Scaling on operational-overhead grounds.
Domain Coverage
Difficulty Breakdown