Middleware tracking about tonic

[LucioFranco]

@rlabrecque would we want to create our own specific grpc middleware library? Ideally, I'd like these middleware to be very closely tied to the tower middleware. That said, Id love to explore these. Some may be more difficult than others.

[davidpdrsn]

With #651 Tower middleware are now much easier to use Tonic. Tower is definitely the right abstraction for middleware like this. I think a good place to start is to write some cool middleware and release them as stand alone libraries on crates.io. Over time if some of them gain traction we can consider moving them into tonic or perhaps tower-http.

I'm going to close this but feel free to reopen if you have further questions.