title: Kinesis stream pending message count
body: <p>I am trying to use AWS Kinesis stream for one of our data streams. I would like to monitor pending messages on my stream for ops purposes(scale downstream according to backlog), but unable to find any API that gives (approx) pending messages in my stream. </p>
  
  <p>This looks strange as messages get expired after 7 days and if the producers and consumers are isolated and can't communicate, how do you know messages are expiring. How do you handle this problem? </p>
  
  <p>Thanks! </p>