After a lot of trouble, I’m really happy that I was able to build an async I/O implementation of my protocol. However, for real code, I think that I would probably recommend using with the sync API instead since at least it's straightforward and doesn’t incur so much overhead at development time. The async stuff is still very much a “use at your own risk” kind of deal from my perspective. And I can’t imagine trying to use it in a large project and no suffering from the complexity.
As a good example, take a look at the following bit of code: