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Etwork is a network abstraction library that lets you use UDP or TCP to send packetized messages between machines using a portable C++ interface.

Etwork serves both as an intermediate portability layer, that will properly packetize messages over TCP (so they don't run together into one), as well as illustrates how code for networking, buffering, and notification can be structured. You don't need to use the entire library to benefit from reading the different parts of the code.