On Building a Middleware Framework

I am fascinated by Middleware Stacks. Middlewares help us to customize a function invocation (typically a request handler) with additional behavior before and after the invocation of function. Popular examples are authentication, logging or exception handling middlewares. Often they handle non-functional requirements (like logging, security, ...).

ReactiveX Middlewares

While implementing sharpbrick/powered-up an interesting problem came up to solve: How to handle the incoming messages of the Bluetooth Low Energy based communication protocol. On top of the Bluetooth abstraction there is a simple callback which would receive roughly 50 different message types which would need dispatching to several locations, some locations would even spawn up dynamically over time. I needed an infrastructure! I needed a middleware 😀.