This week's book giveaway is in the Cloud/Virtualization forum. We're giving away four copies of Learning OpenStack Networking: Build a solid foundation in virtual networking technologies for OpenStack-based clouds and have James Denton on-line! See this thread for details.
It sounds like it is trying to execute the jar, not open it. Basically it is telling you that there is no Main-Class: declaration in the META-INF/MANIFEST.MF file within your Jar file. This is correct if the jar is not meant to be executed.
Windows is not my native tongue so I'm not sure how to change it but you want WinZip to open the file not run it.
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