title: Using AWS Lambda for sending file from S3 to IoT device via MQTT
body: <p>I need to send a file saved in a s3 bucket to a registered IoT device (specifically a ST Nucleo F401RE with wifi shield and 1MB of flash memory).
  I am able to exchange MQTT to and from the device with Lambda, triggering rules that save the message in s3, or write a dynamodb record.
  But I cannot find a way to trigger a rule that sends back to the device a file from s3. I found the createStream function, that according to its description works exactly as I need, and after a while I am now able to successfully create the stream but -and now the question- :</p>
  
  <p>how to retrieve that stream on the device? The created stream hasn't topic or other mqtt coordinates on which make reference. I suspect that I lack same intermediate step. Or there is same other -and simpler- way to accomplish my task?</p>
  
  <p>Thank you very much for your help</p>