Async Networking with asyncio and Java NIO

Low-level event loops are powerful, but they force application code to preserve every partial read, partial write, and state transition manually. Asynchronous programming keeps the same event-driven foundation while letting the program express a connection as a sequence of operations:

When an operation must wait, the current coroutine or asynchronous operation is suspended. The thread is then free to advance other connections. Once the operation can continue or has completed, the runtime resumes the associated work.

This chapter builds the same length-prefixed TCP echo service in two styles:

Both versions use a small, shared wire protocol and listen on port 5005. A Python client can therefore test either server without knowing how the server handles concurrency internally.