writing libnetstat for Summer of Code 2009
ciphwn at gmail.com
Mon Mar 16 15:11:36 PDT 2009
On Mon, Mar 16, 2009 at 5:36 PM, Tim Kientzle <kientzle at freebsd.org> wrote:
> 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.
>> On Mon, Mar 16, 2009 at 3:04 PM, Xin LI <delphij at 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
> 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
> * 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?
Yes, it does, Tim, thank you so much. I'll be sure to look into
sysctl.h and study its ability to return XML. I will also contact
Robert about this project once I finish gathering more info.
Thank you all for answering my questions.
P.S. Sorry about top-posting. I'll be sure to remember it from
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