On Friday 18 November 2005 09:46am, Răzvan Corneliu C.R. "d3vi1" VILT wrote:
On Fri, 2005-11-18 at 00:20 +0200, Gilboa Davara wrote:
> I, too, second the "anything but XML" statement.
> A. Hard to read.
> B. Hard to edit using non-XML editors. (vim in my case)
> C. Tends to create needlessly-complex data structures.
> D. While can be accessed using shell scripts, it requires very complex
> and unreadable code.
> On the other hand, what does XML offer in return?
I don't second that. Today XML is the format everybody uses. Why?
Because it's a standardised way to put any kind of information in a
No. Everybody uses it because product managers come along and say we have to
have XML on "the box" or because programmers are too lazy to write a parser.
Don't get me wrong...XML is *wonderful* for certain things. Configuration
files for UNIX/Linux daemons is not one of them.
A. Depends on how the schema is created. XML files can be easy to
or dificult. Identing the xml code always helps.
Exactly right. Unfortunately, 99% of it seems to go to the "difficult" end of
B. Colored syntax always helps. That's all you usually need. At
it's enough for me. I must say that Midnight Commander seems to work
with XML a little better.
I haven't tried it with mc, but I agree...chromacoding is (almost) always
helpful for any kind of text file; shell scripts, C/C++, perl, XML,
httpd.conf, /etc/fstab, DNS zone files, etc., etc., etc. XML is not special
in this regard.
Also, I will reiterate what others have pointed out, properly indenting (using
tabs/indents and NOT spaces) is extremely helpful. Yeah, I know; in some
groups of users, good luck defining "properly" in that statement.
C. Depends on the schema.
Right; unfortunately, people tend to simply extend the schema at any whim.
For a project with such far reaching implications as
D. It does not require complex code, it requires well designed tools.
a XML based init world, you would need chkconfig and other tools. XML
authoring should be done only by the package maintainers. The rest
should be doable by external tools which share a common API.
Basic UNIX Philosophy: All configuration is in plain-text; all you need is a
plain text editor to configure anything.
I use vi/vim for almost all my text editing (Kdevelop & kate for some of my
programming stuff), but someone should be able to whip out joe or pico/nano
or (gasp!) notepad over SMB and be able to easily
This is not always 100% true (mostly commercial apps, like an RDBMS). You
might say XML is plain-text...well, I would say that XML is text, but not
plain. Look at some of the other respondents comments in this thread; XML is
not easy. It CAN be but almost never is.
XML could help major projects such as the directory server bypass
limitations of the current sysvinit. Check the problems with the
currently proposed init scripts in the fedora-ds wiki.
I haven't had time to look at any of that, yet. If I find some spare time
laying around, I will. Until then, I can not intelligently comment. Of
course, I could just unintelligently comment now, but I'm not sure how to
blow raspberries in email (just kidding).
I've included in this email a demo of a service configuration
Sun SMF. Don't worry, it's not CDDL-ed. You are not contaminated if you
Funny that you included this example. Though I have not yet had any direct
experience with this, you are the first person (outside of Sun) from whom I
have read anything positive about this. It seems clear that the vast
majority (of the email vocal component, of course) of the UNIX/Linux
sys-admin world thinks Sun *way* screwed this up.
The interesting stuff this file brings:
1) Internationalize the service descriptions (the xml:lang attribute is
a dream for i18n in this case).
2) Include information about the documentation.
3) Include dependency information.
4) Include the start-up and shutdown commands.
We can accomplish all of this already today without XML.
There are a lot of other things that can be done using this XML
These are just a few of the ones that I consider important. I've added
gEdit style syntax color in the HTML version ;-).
To sum up my viewpoint: XML is appropriate, but not necessarily the best
choice, when the data to be encoded naturally falls into a tree structure.
There are other "corner" cases where XML could also be appropriate.
The perceived and real complexities in editing XML without breaking stuff
would be enough to put sys-admins off over it. Although any
new-way-of-doing-things will cause growing pains as everybody learns the new
way, in this case the negative effects are going to be amplified to everyone
who uses FC & RHEL.
A SysV Init replacement is not an appropriate application for XML...outside of
dependency relationships, there is nothing that is even close to a tree
structure. Also, it would be very difficult with XML to represent some of
the odd dependency relationships; see the Apache & Tomcat example earlier in
this thread, for one. IMHO, XML would be a big mistake in this instance.
Whatever system we do come up with should use plain text, shell scripts and
have tools like chkconfig ported to "just work".
Here's a really simple idea: change the rc?.d/S## & K## numbers to all be the
same for those things that can be started or stopped in parallel (so all the
S11* 's go together) and have an init or rc (even better) that can decide
about dependencies amongst all the "S11*" services by looking at the LSB info
in the SysV Init scripts. Yeah, I know not the best way to represent the
dependencies, but this solution has the advantage of only needing to modify
either rc or init a little bit and still being "LSB compliant". Go ahead;
shoot holes in this idea, it's just off-the-cuff anyway.
Lamont R. Peterson <lamont(a)gurulabs.com>
Guru Labs, L.C. [ http://www.GuruLabs.com/