How to ensure latest versions of JARs are used with a JNLP application?

I have a desktop application and I want to launch that application using JAVA Web start. It is working fine when I am launch it first time using a browser and it will download all jars defined in resources. Next time I run it using JNLP or from browser, it will not download any jars. The jars that are used come from cache or some where else, I don't know...

I want that every time when my application is launched all jars defined in resources are downloaded

my jnlp file contains :

<?xml version="1.0" encoding="UTF-8"?>
<jnlp spec="1.0+" codebase="" href="">
    <information>
        <title>example</title>
        <vendor>example</vendor>
    </information>
    <resources>
        <!-- Application Resources -->
        <j2se version="1.5+"
              href="http://java.sun.com/products/autodl/j2se"/>
        <jar href="application.jar" main="true" />
        <jar href="lib/app.jar" />             
    </resources>
    <application-desc main-class="com.application.entry">
  </application-desc>
   <update check="background"/>
   <security>
     <all-permissions/>
   </security>
</jnlp>

Solution

It will download jars if there are new versions of them. If not, there is really no need to download files.