Date: Mon, 16 Mar 2009 14:36:22 -0700 From: Tim Kientzle <kientzle@freebsd.org> To: Cipta H <ciphwn@gmail.com> Cc: freebsd-hackers@freebsd.org, d@delphij.net Subject: Re: writing libnetstat for Summer of Code 2009 Message-ID: <49BEC656.50702@freebsd.org> In-Reply-To: <13b997e60903161213t320252dbg56e96335e79f7eb9@mail.gmail.com> References: <13b997e60903160716x21881adfma588c32551c36e6f@mail.gmail.com> <21C1FF9D-4CDA-4476-9F11-3DE281279C1A@freebsd.org> <13b997e60903161141j8faaf7frd6ce9b1423b40164@mail.gmail.com> <49BEA2BC.6000405@delphij.net> <13b997e60903161213t320252dbg56e96335e79f7eb9@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Many people consider top-posting to be rude. FYI.
My comments below, where they belong.
Cipta H wrote:
> Thanks for the reply, Xin. I'm aware of something called sysctl, and if
> I am accepted to work on this project, my main task is to ensure all live
> network data will come from sysctl, but the only XML I know of is the
> markup language. Perhaps someone more knowledgeable can point me
> to the right resource? Thanks in advance.
>
> Cipta
>
> On Mon, Mar 16, 2009 at 3:04 PM, Xin LI <delphij@delphij.net> wrote:
>
>>I'm not very sure but I think Rui is referring XML like the GEOM
>>subsystem has used (perhaps to have the kernel expose the statistics
>>data with XML and the userland part of the library parse and return the
>>result)?
There are two different issues:
* Kernel <-> userland communications
* library <-> client program communications
There is ample precedent for the former to use sysctl
interfaces that return XML from the kernel that is then
parsed in userland. In particular, this makes it much
easier to extend in the future, as long as the proposed
libnetstat library ignores data it doesn't understand.
(In the past, many tools parsed in-kernel data
structures to obtain this kind of information, which is
prone to breakage whenever the kernel changes. Making
this so that kernel and tools can evolve more independently
is a major goal here.)
For the latter, some kind of opaque C structure
makes sense, since that simplifies the client programs.
So really this breaks down into two very different
tasks:
* Designing and implementing a sysctl that returns
network statistics as an XML blob
* Designing and implementing a C library that knows
how to fetch the XML blob, parse it, and return
data to client programs.
Does this make more sense now?
Tim
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?49BEC656.50702>