SAA-C03 Q36 · Serverless

Question

A company is designing a new application that uploads files to an Amazon S3 bucket. The uploaded files are processed to extract metadata. Processing must take less than 5 seconds. The volume and frequency of the uploads vary from a few files each hour to hundreds of concurrent uploads. Which solution will meet these requirements MOST cost-effectively?

Accepted Answer

**Option B: S3 Event Notification → AWS Lambda** satisfies every requirement:

1. **Trigger on upload**: S3 event notifications fire automatically when a new object is created (`s3:ObjectCreated:*`). No polling, no delay — it's event-driven.

2. **Processing time < 5 seconds**: Lambda functions can start executing within milliseconds of being triggered. Lambda's maximum timeout is 15 minutes, but the requirement here is only 5 seconds — well within Lambda's capability for metadata extraction.

3. **Variable volume (few per hour to hundreds concurrent)**: Lambda scales automatically. AWS provisions concurrent executions to match incoming events. Whether 1 file/hour or 500 files/second, Lambda handles it without any capacity planning.

4. **Cost-effective**: Lambda uses a **pay-per-invocatio

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