JXTA handles this by specifying neither. Instead they have a "pipe" abstraction. Once peers discover each other they can open a pipe that may, depending upon

JXTA handles this by specifying neither. Instead they have a "pipe" abstraction. Once peers discover each other they can open a pipe that may, depending upon the network conditions, be a fast TCP implementation (when a direct connection is possible) or a slower, but usable pipe built on HTTP with polling (for being able to traverse firewalls).