lthcheckFile"&gt;server-enabled.txt&lt;/str&gt;
   &lt;lst name="invariants"&gt;
     &lt;str name="qt"&gt;/search&lt;/str&gt;&lt;!-- handler to delegate to --&gt;
     &lt;str name="q"&gt;some test query&lt;/str&gt;
   &lt;/lst&gt;
 &lt;/requestHandler&gt;
 </pre>

 <ul>
   <li>If the health check file exists, the handler will execute the 
       delegated query and return status as described above.
   </li>
   <li>If the health check file does not exist, the handler will return 
       an HTTP error even 