title: How to encode/decode protocol buffer binary data(Integer) to string and string to binary?
body: <p>I am making program using <em>Protocol buffer</em> and <em>smack</em>.</p>
  
  <p>smack (xmpp) only can transfer string type data. and protocol buffer can  produce byte array data.
  so, i do this</p>
  
  <ol>
  <li>make byte[] data using protocol buffer.</li>
  <li>encode byte[] data to string using base64</li>
  <li>transfer using smack</li>
  <li>decode received string(encoded using base64) to string</li>
  <li>change decoded string to byte[]</li>
  <li>parse data from byte[] using protocol buffer.</li>
  </ol>
  
  <p>then every values are perfect without <code>Integer</code> type value.
  the value of <code>Integer</code> is changed.
  the values are in <code>xxxx.proto</code></p>
  
  <p>for instance converting <code>string abc = "hello" int age = 13300</code>
   to  <code>string abc = "hello" int age = 217014255</code></p>
  
  <p>only int is changed</p>
  
  <p>what is the problem?</p>