Answer: Configure the application to upload images directly from each user's browser to Amazon S3 through the use of a presigned URL, Configure S3 Event Notifications to invoke an AWS Lambda function when an image is uploaded. Use the function to resize the image.

## Explanation **Correct Answers: C and D** **C. Configure the application to upload images directly from each user's browser to Amazon S3 through the use of a presigned URL** - This improves website performance by offloading the upload process from the EC2 instances directly to S3 - Users upload images directly to S3, bypassing the EC2 web servers entirely - Reduces load on EC2 instances and network bandwidth consumption - Presigned URLs provide secure, temporary access to upload objects to S3 **D. Configure S3 Event Notifications to invoke an AWS Lambda function when an image is uploaded. Use the function to resize the image.** - Decouples the image resizing process from the upload process - Uses serverless architecture (Lambda) for resizing, which scales automatically - S3 Event Notifications trigger Lambda immediately when new objects are uploaded - Improves operational efficiency by using event-driven architecture **Why other options are incorrect:** **A. Configure the application to upload images to S3 Glacier.** - Glacier is for archival storage, not for active image serving - Glacier has retrieval delays (minutes to hours), unsuitable for user uploads - Doesn't address performance or decoupling requirements **B. Configure the web server to upload the original images to Amazon S3.** - Still uses EC2 instances for uploads, doesn't improve performance - Doesn't decouple the upload process from the web servers - Maintains the same coupling issue as the current architecture **E. Create an Amazon EventBridge (Amazon CloudWatch Events) rule that invokes an AWS Lambda function on a schedule to resize uploaded images.** - Uses scheduled processing instead of event-driven processing - Creates delays between upload and resizing - Less operationally efficient than immediate S3 Event Notifications - Doesn't provide real-time processing **Architecture Benefits:** 1. **Performance Improvement**: Direct browser-to-S3 uploads eliminate EC2 bottleneck 2. **Decoupling**: Lambda function for resizing separates concerns from the main application 3. **Scalability**: Both S3 and Lambda scale automatically with demand 4. **Cost Efficiency**: Pay only for Lambda execution time, no EC2 overhead for processing 5. **Operational Efficiency**: Event-driven architecture reduces manual intervention and monitoring needs

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