title: What is the difference between periodic and punctuated watermarks in Apache Flink?
body: <p>Will be helpful if someone give usecase example to explain the difference between each of the Watermark API with Apache flink given below</p>
  
  <ul>
  <li>Periodic watermarks - <code>AssignerWithPeriodicWatermarks[T]</code></li>
  <li>Punctuated Watermarks - <code>AssignerWithPunctuatedWatermarks[T]</code></li>
  </ul>