How to call a backends job from cron job in java

I created a backends.xml as
<?xml version="1.0" encoding="UTF-8"?>
<backends>
 <backend name="cmdline1">
   <options>
     <dynamic>true</dynamic>
     <public>true</public>
   </options>
 </backend>
</backends>


This back end job calls a servlet using the <url-pattern>/_ah/start</url-pattern> from the web.xml.

and i called this back end job from a cron.xml

<?xml version="1.0" encoding="UTF-8"?>
<cronentries>
  <cron>
    <url>/test</url>
     <schedule>every 1 minutes</schedule>
    <target>cmdline1</target>
  </cron>
</cronentries>.

But i tapped the servlet using req.getRequestURI(), the servlet is always call using the url /test and not call from backend job except in the case of initial application run. Is this way is correct ? Or how can i call backend job from cron.xml?