A solutions Architect has been asked to design a serverless media upload web application that will have the functionality to upload thumbnail images, transcode videos, index files, validate contents, and aggregate data in real-time. He needs to visualize the distributed components of his architecture through a graphical console.
How can this be designed wisely?

Answer options:

A.Host a static web application using Amazon S3, upload images to Amazon S3, trigger a Lambda function when media files are uploaded, coordinate other media files processing Lambdas using several SQS queues, and store the aggregated data in DynamoDB.B.Host a static web application using Amazon S3, upload images to Amazon S3, trigger a Lambda function when media files are uploaded, coordinate other media files processing Lambdas using Simple Workflow Service, and store the aggregated data in DynamoDB.C.Host a static web application using Amazon S3, upload images to Amazon S3, trigger a Lambda function when media files are uploaded, process media files using various Lambdas, and store the aggregated data in DynamoDB.D.Host a static web application using Amazon S3, upload images to Amazon S3, use S3 event notification to trigger a Lambda function when media files are uploaded, coordinate other media files processing Lambda using Step functions, and store the aggregated data in DynamoDB.

Correct Answer : D
As an above diagram, Steps functions are used to coordinate processing Lambda functions and store the data on DynamoDB.Differences between Steps function and SWF are as follows:
Step Functions
SWF
Good for any new serverless application where coordination is required between various components using a visual workflow
Need external signals to intervene in processes, OR Good if there are child processes and those require passing signals to parents.
Easy to use while developing application
More complex while developing application but complete control of orchestration logic
Uses declarative JAON to write state machine
Need to write decider program (programing of your choice) to separate activities between steps or use AWS flow framework
Serverless, lower admin overhead
Uses servers
Short running workflows
Long-running workflows,
Mostly used for synchronous tasks
Mostly used for asynchronous tasks
New AWS Service, less complex applications
Legacy application, Complex decisions (custom decide application)
Integrate with AWS Mechanical Turk
Option A is incorrect: Using SQS queues to coordinate several Lambda functions is not suitable.
Option B is incorrect: SWF can manage workflows, but managing Lambda functions with step functions are better. SWF is used to manage the infrastructure that runs workflow logic and tasks. SWF is the least used service
Option C is incorrect: Managing Lambda functions will be challenging without a managed workflow service such as Step functions.
Option D is CORRECT: This is the best answer as Step functions are used to coordinate the processing of Lambda functions. It also provides a graphical way to visualize the processing steps.
 Reference:
https://aws.amazon.com/step-functions/faqs/
https://aws.amazon.com/step-functions/use-cases/