在客户端计算机上运行java代码

I want to run a java code which uses JNA to find out whether the client machine is idle or not. This code must run on the client side JVM instead of server's JVM hence I can't put the code inside servlets. I was able to achieve this by using applets. But as I dont want any GUI and want this code to run in background, is there any way to run a piece of code on cilent's JVM? I am using I want to run a java code which uses JNA to fin