Hey dsab! I agree, but CCSDS is what we have today. We need to support it properly first if we ever want to extend or transition away. It also doesn't help that there's no good open-source implementation of the whole stack, especially the SDLS part, which makes the transition even harder.
On the type-safety side, I found typed combinators really useful for describing parsing and serialising (see my earlier post on ocaml-wire[1]), and keeping the protocol logic pure (separate from I/O) makes the whole thing much easier to test and reason about. OCaml's fuzzing support pairs really well with types too. This is basically the nqsb-TLS approach [2], which has held up in ocaml-tls for a decade.
Hey Maksadbek! Great question. It's a trade-off between speed of writing and trust in what you wrote, and OCaml (especially OxCaml) sits at a really good point on that curve.
Ada/SPARK has the strongest verification story and decades of space heritage, but the development cost is higher. Rust would work too, but I actively want a GC by default with the option to turn it off on the hot path. That is exactly what OxCaml's mode system gives you: zero minor GCs on the dispatch loop in the post, while the rest stays GC-managed. Haskell is great for type-driven design but its runtime cost-model is harder for low-jitter work.
Plus, the OCaml ecosystem gave me solid foundations on both fronts. For the protocol stack: MirageOS-style clean separation between wire serialisation, pure state-machine management and I/O, with ML modules and GADTs that map naturally onto protocol state machines. For the crypto: mirage-crypto for OCaml-facing primitives (fiat-crypto under the elliptic curves), and libcrux for ML-DSA-65 post-quantum signing. The CCSDS and BPv7/BPSec layers themselves I had to write from scratch (my earlier posts walk through how), and 20 years of OCaml muscle memory definitely helped!
Hey Berké! I remember your talk very well (I was in the room), super interesting and it really got me thinking about this area!
Since then, the more I look into it, the more I see a fit with our MirageOS unikernel work. On the ground, you can paper over security and specialisation by throwing more machines (or money) at the problem. In orbit you cannot, so both the compile-time and the runtime guarantees have to be right!
Absolutely, MirageOS is indeed pivotal in the development of unikernels. MirageOS not only developed the unikernel concept but also coined the term 'unikernel'.
MirageOS represents a significant shift in cloud and network computing, focusing on building highly specialized, secure, and efficient unikernels that streamline application deployment by shedding unnecessary components. It also puts extra focus on security, with most of the stack — including TCP and TLS — being rewritten in a type-safe language (OCaml).
Currently, MirageOS is expanding to include bare-metal and embedded systems, aiming to bring the same level of security and efficiency to this domain. The move towards embedded systems is a natural progression for MirageOS, given our emphasis on minimalism and security in environments where resources are limited and reliability is crucial. See for instance what is happening with SpaceOS: https://tarides.com/blog/2023-07-31-ocaml-in-space-welcome-s...
Hey dsab! I agree, but CCSDS is what we have today. We need to support it properly first if we ever want to extend or transition away. It also doesn't help that there's no good open-source implementation of the whole stack, especially the SDLS part, which makes the transition even harder.
On the type-safety side, I found typed combinators really useful for describing parsing and serialising (see my earlier post on ocaml-wire[1]), and keeping the protocol logic pure (separate from I/O) makes the whole thing much easier to test and reason about. OCaml's fuzzing support pairs really well with types too. This is basically the nqsb-TLS approach [2], which has held up in ocaml-tls for a decade.
[1] https://gazagnaire.org/blog/2026-03-31-ocaml-wire.html [2] https://www.usenix.org/conference/usenixsecurity15/technical...