The DVA-C02 exam tests practical knowledge of how to build applications that integrate with AWS services using common developer tools and patterns.
- AWS SDK: Available for multiple languages (Python/Boto3, Java, JavaScript, .NET, Go, etc.). The SDK handles request signing, retries, and response parsing automatically. Credentials are resolved in a specific order: environment variables, shared credentials file, IAM role for EC2/ECS/Lambda.
- AWS CLI: A command-line tool built on the Python SDK. Uses the same credential resolution chain. Useful for scripting and automation. Output can be formatted as JSON, text, or table.
- API Calls and SigV4 Signing: All AWS API requests must be signed using Signature Version 4 (SigV4). The SDK and CLI handle this automatically. When making raw HTTP requests, you must sign headers manually.
- Pagination: Many AWS API responses are paginated. Use NextToken, Marker, or similar fields to retrieve subsequent pages. SDK paginators simplify this with automatic iteration.
- Exponential Backoff and Retries: When receiving throttling errors (HTTP 429) or transient 5xx errors, implement exponential backoff. The AWS SDK retries automatically by default (configurable retry count).
- Presigned URLs: Allow temporary, time-limited access to S3 objects without requiring AWS credentials in the client. Generated server-side using the SDK.
- Environment Variables for Configuration: AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN, and AWS_DEFAULT_REGION are standard environment variables recognized by the SDK and CLI.
- IAM Roles vs. Access Keys: Best practice is to assign IAM roles to compute resources (EC2, Lambda, ECS tasks) rather than embedding long-term access keys in code or configuration files.
- AWS X-Ray SDK Integration: Instrument application code with the X-Ray SDK to trace requests across services. Requires the X-Ray daemon to be running alongside the application.
- Common Service Integrations: The exam frequently tests SDK usage patterns for S3 (PutObject, GetObject, presigned URLs), DynamoDB (PutItem, GetItem, Query, Scan), SQS (SendMessage, ReceiveMessage, DeleteMessage), and SNS (Publish).
Focus on credential resolution order, retry/backoff behavior, pagination handling, and the difference between SDK-managed operations and raw API calls when preparing for exam questions.