asyncvarlink

Varlink is an inter-process communication protocol based on JSON and bidirectional streams between two processes. There are multiple implementations for various programming languages including the reference implementation for Python. asyncvarlink is an alternative implementation in pure Python using different design choices. There are three main differences.

• As the name implies, it is based on asyncio. If you prefer synchronous interaction, consider wrapping your interaction in asyncio.run or using the reference implementation.

• Interface definitions are modelled as typed Python classes and the actual varlink interface definition is rendered from those classes. In contrast, the reference implementation parses interface definitions. As a consequence, using an existing varlink interface definition requires translating it to a Python class. This may seem like an odd choice initially, but there often are multiple Python types suitable for representing a varlink type. The reference implementation is less flexible and has a fixed type choice.

• Even though the varlink FAQ explicitly renders passing file descriptors out of scope, systemd uses that feature. Therefore asyncvarlink implements the same file descriptor passing scheme whereas the reference implementation does not.

Contents

• Usage
  • Installation
  • Client
  • Defining an interface
  • Server
• Structure