title: Do I need any Rules Engine to build a service like ifttt.com ( if this then that )?
body: <p><strong>I'm trying to build a web service like <a href="http://www.ifttt.com" rel="nofollow noreferrer">ifttt.com</a> .<br>
  Because I find that more than a half of the channels provided by ifttt is not available in China. So I decide to make a local one.</strong>  </p>
  
  <p><img src="https://i.stack.imgur.com/2ZUrI.png" alt="unavailable services here"></p>
  
  <p><strong>I'm learning the Logs of ifttt trying to understand the process of how ifttt dealing with tasks.</strong>  </p>
  
  <p><img src="https://i.stack.imgur.com/uPdts.png" alt="ifttt rules&#39; logs here"></p>
  
  <p><strong>Now I know that I must have some method to deal with the rules.<br>
  A scheduled task process can be activated by a specified event and then a engine resolve rules to call specified actions, passing parameters.</strong></p>
  
  <p>I'm planing to use Java to develop this.<br>
  And do you think I should use any open source Rules Engine here, or it's better to write one by myself? It will be great if you provide some hints about what I should be care for writing the rules engine or defining the structure of rules.</p>
  
  <p>Finally, welcome free discussions about what technology do you think ifttt might be using. Or what the Database Structure of ifttt might be like. Or.. any point about ifttt or Rules Engine or Scheduled Tasks will be helpful!</p>