P2 is a system used for the declarative construction of networks. P2's language OverLog can be used to specify overlays very concisely, requiring only 16 rules to express a Narada-style network and 47 for a Chord overlay. However, the conciseness of OverLog does not necessarily speak for the learnability of the language. Better readability (a la SQL) would help its popularity, particularly since OverLog's declarative nature is already somewhat foreign to the typical imperative-language programmer.
P2's modularity is useful in that unlike PIER, P2 can be used with a variety of underlying networks, building up a knowledge of the network from a small set of nearby neighbor addresses. Its architecture is based on Click, though P2 differs from Click in that P2 elements are meant to act as database operators rather than packet routing functions. Performance testing of P2 Chord overlays revealed expected performance on par with those of Chord itself. The results of hop-count, latency, and performance under churn were "acceptable" as the authors didn't expect to compete with hand-tuned implementations.
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