Welcome to your CDK TypeScript project

You should explore the contents of this project. It demonstrates a CDK app with an instance of a stack (CdkTypescriptApiStack) which contains an Amazon SQS queue that is subscribed to an Amazon SNS topic.

The cdk.json file tells the CDK Toolkit how to execute your app.

Useful commands

• npm run build compile typescript to js
• npm run watch watch for changes and compile
• npm run test perform the jest unit tests
• cdk deploy deploy this stack to your default AWS account/region
• cdk diff compare deployed stack with current state
• cdk synth emits the synthesized CloudFormation template

Deployment steps

• Download the code from the repo
• go to the root directory of the project
• run npm cache clean --force and then npm install to install the required libraries
• run cdk bootstrap which will install the bootstrap stack of the environment
• run cdk deploy -c email_acc=<email account>. in place of <email account> place your email account. After deployment check your email and confirm the subscription.
• add data into DynamoDB. There are two columns that need to be populated with the following format: id-value.
• copy the generated url from the command line and add /client/<id> for example https://orrfby8ayb.execute-api.eu-west-2.amazonaws.com/prod/client/1 to see how many payments have been made for a particular client. If there are 2 or more an email with the confrimation should be generated.

Scalability

As lambda serverless functionality is used it means that we don't have to worry about scalability that much as lambda function will be scaled by AWS if more instances is needed. There is a limit of cumulative concurrency per Region which is between 500 and 3000. So in case if the limit is crossed we can either create another lambda instance in another AWS region or submit a request to AWS Support Center to increase the default limit or both. With DynamoDB in order to scale it we will need to create a scaling policy for a table where we will need to specify whether we will scale write or read capacity (or both). There are some other params that can be specified (min/max provisioned capacity unit, target utilization etc) which will allow to fine-tune the performance.