Re: [MirageOS-devel] Charrua release

["Christiano F. Haesbaert" <haesbaert@xxxxxxxxxxxxx>]

On 30 September 2015 at 18:50, Richard Mortier
<richard.mortier@xxxxxxxxxxxx> wrote:
> [ Adding the list as discussion may be of more general interest. This
> concerns Christiano's DHCP server, Charrua, at
> https://github.com/haesbaert/charrua-core,
> https://github.com/haesbaert/charrua-mirage and
> https://github.com/haesbaert/charrua-unix. ]
>
> On 30 September 2015 at 13:39, Christiano F. Haesbaert
> <haesbaert@xxxxxxxxxxxxx> wrote:
>>
>> On Wednesday, 30 September 2015, Richard Mortier
>> <richard.mortier@xxxxxxxxxxxx> wrote:
>>>
> ...
>>> Some random thoughts:
>>>
>>> + Is there a reason why you include clock.mli rather than depending on
>>> mirage-types and using the definition from there?
>>
>> Probably inexperience, that was for charrua-unix to be able to use the Ocaml
>> Clock module without having a functor, but I want to change that, didnt find
>> a better way at the time.
>
> Given you're using functors elsewhere, why is it a problem to use a
> functor for Clock too?
>
>>> + I notice the INTERFACE type you define -- is this something that we
>>> should think about adding to mirage-types?
>>
>> Don't think so.
>> This is an artifact of having the library working outside mirage
>> (charrua-unix), i basically need to tell the Server module how to do IO and
>> what is an interface. Im not too happy with the way I wrote this, perphaps
>> there is a better way ?
>
> This may bear some thinking about-- I wonder if the right thing to do
> is to just use the Mirage types, functors, libraries, etc, but (using
> @drup's shiny new Functoria-based Mirage DSL implementation) implement
> a "native Unix" backend so that cmdliner and other things can be used
> as-is. That way you can leverage the module types and libraries all
> the way down, but aren't tied to having the entry point look like a
> unikernel (hence can pass params etc as you would normally).
>
> All-- thoughts?
>
>>> + Could you pull out Dhcp_structs into a separate ocamlfind library (i
>>> tried tftp.wire for my Tftp lib) so that the structs can be reused (eg
>>> in a packet parsing libpcap-alike)?  (One day this will happen for
>>> tcpip as well so that you don't need to include "cstruct udp" et al.)
>>> I can try and put a PR together for this if you prefer...
>>
>> Sure let's do it, but by PR you mean ?
>
> Pull Request :)
>

So I gave a stab at this, but it seemed pointless without the cenum
conversion, the only thing left would be a cstruct Dhcp.
I had a look on your tftp library, and it seems all the parsing and
such is in tftp.wire itself, while mine is in dhcp.ml, I only use a
Dhcp_structs (which now I renamed to Dhcp_wire) so that the cstruct
definitions play nice with merlin.
Should we keep both ? I like the idea of a Dhcp module, and I think
that is more important to be a separate library than the Dhcp_wire, or
maybe both should be separated ?
I'm starting the cenum conversion and that might shed some light on
how to proceed.

>>> + Curiosity: Was there a reason to not use the Cstruct `cenum`
>>> construct for declaring the codepoints etc? (Wondering whether
>>> something that replaces `cstruct ... { }` could/should be replaced
>>> with something that enables`with cstruct` a la `with sexp`.)
>>
>> i didn't know about cenum, that will make things easier, I will work on that
>> thus week.
>
> Cool. In general I think we have an inclination now to remove camlp4
> syntax extensions where possible -- I don't know if anyone has looked
> at replacing cstruct.syntax though (which I would guess is the most
> commonly used now we don't generally use lwt.syntax). Anyone?
>
>>> + Dhcp_logger -- Anil, what's the status of dog at the moment? Is
>>> there a logging framework ready for use/Is dog the place to start for
>>> one? (I'll push Tftp over onto it as well if so.)
>>
>> That was also to be able to use charrua-core outside of mirage.
>
> I understood that Dog depended on Irmin rather than Mirage, but I
> might be wrong. (@samoht?)
>
>>> + Alistair had started adding (possibly got to some kind of
>>> completion) Irmin support for the state in his version (based directly
>>> off mirage-tcpip --
>>>
>>> https://github.com/alistairfisher/irmin-dhcp/commit/fb56e771613333d08397033b8c4f830a519db5a0)
>>> -- would be great to look at adding/merging this somehow.
>>
>> I agree, i can work on merging his code, I would do it for 0.2 though.
>
> Fair enough :)
>
>> Bear in mind my ocaml-foo may not be on paar, you should see other naive
>> mistakes and/or uncommon idioms.
>
> I'm sure those with sufficient experience will eventually point them out :)
>
>> If supporting Charrua-core outside of mirage contaminates too much of the
>> design, I can drop charrua-unix. This was in fact my first idea, but then I
>> figure it would be interesting on the architectural level, since it provides
>> a stronger separation between the core logic and the rest.
>
> FWIW, what I was trying to do with `ocaml-tftp` was to have the
> library and then Mirage and (pure) Unix servers (and ultimately,
> clients) in a single repo, under different directories, using Oasis to
> generate the necessary build runes and OPAM to manage installation of
> different generated ocamlfind components. (Though I just noticed I
> need to split that down more.) Not entirely successful (or finished!)
> so far, but it mostly seemed to work. (And meant I didn't have to
> worry about too many repos.)
>
> --
> Richard Mortier
> richard.mortier@xxxxxxxxxxxx

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