title: XSD - validation
body: <p>My requirement is like, consider the following sample xml</p>
  
  <pre><code>&lt;user key="username" value="Test"/&gt;
  &lt;user key="age" value="27"/&gt;
  &lt;user key="email" value="my@my.com"/&gt;
  </code></pre>
  
  <p>In this case all the element having same name, same number of attributes and same attribute names too..</p>
  
  <p>but i need to validate the <strong>value</strong> attribute according to <strong>key</strong>. For example here first key is username and its value is a string type, second key is age and its value must be a positive integer and third key is email so the value should be an email address.</p>
  
  <p>is there any way to achieve this.</p>