title: Watch mongo update events using oplogs
body: <p>I have to Listen to changes in particular field in mongodb documents and send data to client accordingly</p>
  
  <p>I have tried looking for solutions, but only thing I could find is to query oplogs 
      (operation logs) of mongodb.</p>
  
  <pre><code>db.collection("oplog.rs", function(err, oplog) {})
  </code></pre>
  
  <p><strong>Questions</strong>:</p>
  
  <p>How are we actually going to make decisions based on oplogs (<strong>Capped Collections</strong>) and how frequently are we going to query oplogs to see the changes ?</p>
  
  <p>Do we have any alternative solution to this problem may be using mongoose ?</p>