Moving on

Simon Perreault nomis80 at videotron.ca
Wed Jun 13 20:18:27 PDT 2001


On Tuesday 12 June 2001 23:20, Gerard Beekmans wrote:
> Can you tell RPM to read a configuration file (XML or whatever format)
> and then parse it and run commands based on it that compile a package
> and install it according to the instructions laid out in that file?

Yes, it's called a spec file.

> Perhaps my knowledge of RPM is too limited (so please do correct me) but
> I see RPM as a tool that unpack an rpm file and puts some files where
> they belong. I don't see RPM actually compiling from source according to
> a set of instructions.

Yes it can. RPM can do just anything. Take a look at 
http://www.rpm.org/max-rpm/ for more info concerning RPM. Pay special 
attention to section II.

> RPM forces you to have RPM installed on the system. XML forces you very
> little, other than _a_ kind of parser, be it a C program (nothing needed
> except a kernel), or perl, or java or bash. That way you just provide
> the xml profile (see it as a configuration file) and some kind of
> program to parse it (binary program or script language) and voila you
> get your LFS system.

I still don't get how our XML profile is any different from a shell script. 
That's my main concern.

> Well yes of course sequential. If you don't install things in a certain
> sequence you don't end up with a working LFS system.

Well then, how come we don't simply use shell scripts? Don't tell that you 
want to use C because it's faster than shell. You wouldn't see the 
difference, most of the cpu cycles will be taken by gcc.

> The ALFS tools developed are all XML based. The decision to use XML was
> influenced by the package management issues. How many people can
> actually read an RPM spec file and understand it?

It's very easy, actually. Very very easy I'd say. At least as easy as an XML 
profile.

> Or know what an RPM
> database looks like and how it exactly works?

That's why we want XML? To be able to know how the database works?

> We hear comments in the lines of "rpm seems to work, most of the time,
> but I have no idea how it works or what is happening which actually
> scares me". With an ALFS package management system all you need to
> understand is the ALFS DTD. Other components used (XML, XSLT, etc) are
> all accepted standards and there are a lot of books and other
> information available on them.

Uh, RPM is easy to understand. It runs shell commands in different sections 
(prep, for example, is run at the beginning), and then packages some files 
(which you have to list by hand) and makes a nice installable archive, while 
figuring out some dependencies itself using ldd.

> If you compare the information available on XML, XSLT and people using
> XML in general to the same for an rpm, deb or even a BSD port and you
> can see why XML is so much more powerful. Plus, it's easier to read.

XML can't be compared against RPM, as XML is much more than a package 
management system.

> Have a read through the ALFS archives if you want, there's a lot of info
> why we don't use rpm or similar approaches. I have voiced numerous times
> to actually support RPM. You can simply create an RPM database, based on
> what the XML profile/backend are going to install. But again we don't
> want to force RPM or DEB or any format. We provide plain text which
> opens a wide variety of backends and package managements (wants an mysql
> based package management? Could be a piece-of-cake)

Sorry, but I'm still skeptical. Before embarking on a project, we must know 
why we want to do it (and no, the coolness factor, while attractive, won't do 
it). So my question remains: what does XML give us over RPM?

-- 
Simon Perreault -- Public key: http://nomis80.linuxfromscratch.org/nomis80.gpg
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