title: esper controlling event counts
body: <p>I have used esper to join streams as:<br/><img src="https://i.stack.imgur.com/wslAo.jpg" alt="enter image description here">
  <br/>
  Now consider a scenario:<br/>
  1. Two trades entered into system<br/>
  2. Price arrived<br/>
  <br/>
  In this scenario Grouping stream will generate two outputs one each for a trade. And this will also trigger two events out from final output. As no of events increases no of output events will also increase.<br/>
  Now if a trade with <br/>
  Id - 03<br/>
  Symbol - GOOG<br/>
  Quantity - 300<br/><br/> is entered into system, it will also triger 3 new events as %ageMV is also changed for each Id. As no of events increases it becomes difficult to handle on UI.<br/>
  <br/>
  So my question is - <br/>
  <strong>Is there any standard way of doing this?</strong></p>