We introduce Join Voyager - a language that can be used to program a Peer to Peer network using object oriented techniques and Join methods. In Join Voyager any object can migrate to any node (peer) of the underlying network. The language provides strong mobility, i.e. the ability to capture and transfer the full execution state of mobile objects at any time. Objects can communicate by sending and receiving messages in object oriented style. As in Join Java or Polyphonic C#, both synchronous and asynchronous messages are supported. The paper presents the design rationales and a semantic interpreter for Join Voyager. The interpreter is designed with continuations following the discipline of denotational semantics and is implemented in Haskell.

The current abundance and complexity of P2P architectures makes it extremely difficult to assess their performance. P2PTester is the first tool devised to interface with, and measure the performance of, existing P2P data management platforms. We isolate basic components present in current P2P platforms, and insert "hooks" for P2PTester to capture, analyze and trace the interactions taking place in the underlying distributed system.