In a struts application's Action class I am running an external windows application using Runtime class's exec method. It is intended to run an application in background at server side to process a video file uploaded from the client machine. . Everything worked well with in my development machine which is a windows vista running the tomcat6 as executable. When I tried to deploy and run it from another machine which is a windows 7 running tomcat 6 as a service , the exec didn't worked as I expected. I couldn't find the external program running. For the tomcat service I enabled 'Allow service to interact with desktop' - property. After that I could see, when the 'exec' is invoked, the program is actually invoked and is in the background. An interactive service detection message box is shown with a message that 'A program might need information from you or your permission to complete a task' If I view the details, I can see the external program invoked and is waiting. If I click on that program window , it completes.