I would look at my own app-server: https://github.com/tinspin/rupy https://github.com/tinspin/rupy It's not the most well documented but it's the smallest impl

I would look at my own app-server: https://github.com/tinspin/rupy https://github.com/tinspin/rupy It's not the most well documented but it's the smallest implementation while still being one of the most performant so you can learn more than just SSE.