title: AWS: Trigger event if DynamoDB table row is not updated in the last 30 minutes
body: <p>I have to set up a management on an AWS process.
  To keep things simple I have some clients that sends me heartbeat, let's say every 5 minutes, via SOAP requests to my SOAP server deployed on an Elastic Beanstalk NodeJS app. Every time I receive a heartbeat, I store the last time I received it on a DynamoDB table by updating a field on the table. </p>
  
  <p>I now need to create a process that, if I haven't received an heartbeat in the last 30 minutes, does stuff (updates another tables, calls Lambda functions, etc). I don't know now how many clients I will have, but they will be pontentially growing with time, and connected to my server 24/7.</p>
  
  <p>I was hoping on something like an event that triggers a Lambda function (or posts a message on a SNS topic) after those 30 minutes that that specific row in the table is not updated, but I don't know how to get this last part to work. This event should be checking every row in the document.</p>
  
  <p>How would you do it?</p>
  
  <p>Thank you!</p>