Question for use in an application...

[jadamcrain]

Hi @jamesmunns. Loved your talk from RustNL. I'm prototyping a custom protocol for exchanging industrial (battery energy storage) over TCP and TLS.

The "firmware" side of this will run on capable embedded Linux IPCs, e.g.:

https://www.moxa.com/en/products/industrial-computing/arm-based-computers/uc-2200a-series

The first issue I'm looking at is implementing WireTx/WireRx on the host side. I only plan to run this on transports where you get an ordered stream like TCP. I've looked at the serial implementation and for inspiration and see how it uses COBS.

What do you think is the best solution for framing in this situation? I could see just using something like u16 prepended length or just using COBs too.

[jamesmunns]

Hi there @jadamcrain, sorry for the delay in getting back to you, you caught me right as I was at Embedded World.

I do use postcard-rpc over TCP for Poststation's SDK interface, I personally use COBS for this, you PROBABLY could get away with length-prefixed termination, though there is still some room for error in TCP, TCP+TLS is probably bullet proof enough to trust it there.

I don't have a TCP server impl I can easily share, Poststation internally doesn't EXACTLY work as a normal postcard-rpc server impl, so I do some of the dispatching/handling manually to fit what I need. That's why I've only shared the client impl in #86. Poststation also manages self-signed certs, using rustls, to allow for secure SDK interactions.

I'd be open to merging a PR that takes the client from #86 (which is already generic over AsyncRead/Write, so works with or without TLS), if you end up also writing a server impl as well. If you aren't sure how to do this, just let me know.

Happy to chat if there's anything I can help with.