I need to design and develop a distributed desktop application. The application is supposed to be server and client at the same time. Any user who has a copy of application, can define a new IP address to get connected to another running copy and these to copies should be able to share images (screenshots) and some files between each other. So which technology is fitting my need? RMI? Socket?... We need to prevent the apps get caught by firewalls, if possible.

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