Re: [linux-lvm] Writing forward compatible applications using /proc

[Joe Thornber <thornber@btconnect.com>]

On Sat, Aug 11, 2001 at 11:57:18PM -0400, Jason Tackaberry wrote:
> I have some ideas for a comprehensive GUI disk administration tool, and
> I am first thinking about some of the issues I'll face regarding
> interfacing with controllers, disks, partitions, md, and LVM.
> 
> I am curious if it's a silly idea to write an application that relies on
> the data in /proc?  Do the kernel developers attempt to keep the data
> and format provided in /proc as stable as possible?  Or is it fair game
> for trivial changes that could break applications that parse it?  Should
> I use ioctl instead?

We won't change the format of the /proc data for the 1.0 series of LVM
(including 0.9.1 betas).  I do *not* suggest you use the ioctls directly, at
some point the ioctl interface will change.

> I don't mind having to release a new update to be compatible with a new
> format in /proc every once and a while, but if it's constantly a moving
> target I may want to look at alternatives.

You should also be able to get all the information you need from the tools.

> 
> I also have the same question with LVM related tools.  Is it sane to try
> to wrap a GUI around lvm tools or is there some API approach that would
> be better?

I would much rather see people wrapping the tools than using liblvm, in fact
liblvm will probably disappear in the future.

It would be really good to see a comprehensive LVM gui tool.  You
should certainly dig up Jorg de Jong's Java based gui to get ideas
(http://www.xs4all.nl/~mmj/lvm/), from the screen shots it looks nice.
Are you planning to implement in C and gtk ? or use some higher level
language ?

- Joe