I am new to webstart concepts. While dowloading a new version webstart application, I would like to get the differrence in the jar from the current version. I tried with jardiff using the download servlet. My understanding is that both the versions of the jar needs to be packaged to the war file to get the delta. Is there any that web start will check the jar version which is downloaded to the client. Because in an automated build environment it is very difficult to keep the previous version of the jar also in the war. Please let me know am I doign any mistake.