- As a developer, I want to extract data from IoT devices and preprocess it at the fog layer to reduce the volume of raw data sent to the cloud. - As a user, I want to store processed data in a database for long-term analysis and visualization. - As a developer, I want to log ETL pipeline failures for debugging and reliability improvements. - As a system administrator, I want data transformations (e.g., filtering, aggregation) to be customizable for different IoT applications.