Calculator app with AWS

A simple calculator application that works between AWS services with GitHub Actions for ci/cd.

Requirements

• Two functions app that work between each other
• CI / CD

Database Design

We require to store reference for the user calculation file.

Hash Key: userId Range Key: timestamp || latest

reference: string createdAt: string

Functions

Calculate

REQUEST: POST
VALIDATION: {
    firstNumber: string
    secondNumber: string
    userName: string
}

1. Calculate function checks for validity of input data of POST request.
2. Send a SQS Message to a CALCULATION_QUEUE name/queue url.

Process calculation

1. A lambda that handles the SQS messages and sums the numbers up.
2. Save results in S3 for specific user.
3. Stores reference to these results file in DynamoDB.
   • Uses userId as PK and sortKey of either timestamp or latest
   • When creating a record, we will have to make 2 item updates:
     • Put: one item sortKey as timestamp
     • Put: one item sortKey as latest

Get user calculation

1. We receive a GET request with userId as parameter.
2. Search dynamoDB acces for that userId. Get the reference to results.
3. Fetch results from S3 document, parse them and return response as JSON.