Use Unix Domain Sockets on Windows Python: Building an AF_UNIX Compatibility API

Python provides socket.AF_UNIX , asyncio.open_unix_connection() , and asyncio.start_unix_server() for working with Unix Domain Sockets on Unix-like operating systems. On Windows, however, support for Unix Domain Sockets tends to depend on the Python version and runtime environment. In particular, differences become apparent when trying to use the higher-level asyncio APIs in the same way as on Unix. To address this, I created a compatibility layer that hides the differences between Unix and Windows and allows AF_UNIX sockets to be used through a largely identical API. This article covers two types of APIs: An asyncio -based AF_UNIX compatibility API A synchronous socket -based AF_UNIX compatibility API Goal The objective is straightforward. On Unix, use the standard library APIs as-is. On Windows, fill in the missing functionality so that application code can remain as unified as possible. For example, on Unix you can write: reader , writer = await asyncio . open_unix_connection ( path ) And on the server side: server = await asyncio . start_unix_server ( handle_client , path ) The goal is to preserve this style of programming on Windows as much as possible. What Was Built The compatibility layer consists of two major components. 1. Asyncio Version This is the asynchronous implementation designed to match the asyncio Unix Domain Socket APIs. The main APIs are: await open_unix_connection ( path , * , limit = ...) await start_unix_server ( callback , path , * , limit = ..., backlog = ...) await create_unix_connection ( protocol_factory , path , ...) await create_unix_server ( protocol_factory , path , ...) install () On Unix-like systems, these simply delegate to the standard asyncio implementation. On Windows, they use Winsock AF_UNIX sockets and combine WSAEventSelect with event-loop handle waiting to implement asynchronous operations. 2. Synchronous Socket Version This version provides a traditional blocking-socket-style API without using asyncio . The main APIs ar