title: What does this mean: Msgpack is JSON compatible
body: <p>I have read on various sites that Msgpack is JSON compatible? What does that really mean? 
  Example of this claim: 
  1) <a href="https://stackoverflow.com/a/6357042/64758">https://stackoverflow.com/a/6357042/64758</a>
  2) <a href="http://blog.andrewvc.com/why-arent-you-using-messagepack" rel="nofollow noreferrer">http://blog.andrewvc.com/why-arent-you-using-messagepack</a></p>
  
  <p>If I have the following json (written using json.org java library); how would one write that in MsgPack</p>
  
  <pre><code>    JSONObject obj = new JSONObject();
      obj.put("key1", "value1");
      obj.put("key2", "value2");
  </code></pre>
  
  <p>{"key1":"value1","key2":"value2"}</p>
  
  <p>How would one write similar using Msgpack? I dont see a concept of 'key/value' pairing in there</p>