[asterisk-users] Using XML for configuration management, single-source-of-truth, etc.

[Tilghman Lesher]

On Saturday 08 December 2007 00:51:44 Philip Prindeville wrote:
> Tilghman Lesher wrote:
> > On Friday 07 December 2007 20:12:12 Philip Prindeville wrote:
> >> Darryl Dunkin wrote:
> >>> You can store most of the configurations in a database which may be
> >>> more accessable to you.
> >>>
> >>> Perl can also parse these configurations quickly enough if you know how
> >>> to use the input record seperator ($/) properly.
> >>>
> >>> The only thing Asterisk will not store which you would probably need is
> >>> the actual MAC address of the phones themselves. This may be done
> >>> easily enough as comments in the users sip.conf section.
> >>
> >> That's sort of my point:  that you have to reinvent it, and it's easy to
> >> get wrong.
> >
> > XML wouldn't make it any less wrong.  There's a difference between
> > parsing it syntactically (which XML fixes) and parsing it semantically
> > (which XML does not).
> >
> > In fact, I find the configuration files, as they are now are much EASIER
> > to parse than XML.  With XML, you need to load up a whole state engine to
> > ensure the config is properly formatted.  At the simplest level, the
> > config file as-is is simply a set of key/value pairs, which syntactically
> > is very easy to parse.
> >
> > Part of the allure of the current format is also that it is human
> > readable, which assists in manual editing.  I'm not sure what part of the
> > universe you have be from to make XML human readable (or more
> > importantly, human-editable), but I am quite sure it is not from this
> > planet.
>
> Well, after hand-coding HTML and SGML for 15+ years, XML isn't all that
> much of a stretch.

And so can I, but to most people, XML looks like gobbleygook.  BTW, 15+ years
for a markup language (HTML) that has only been around for 14 years?

> More to the point though, there are some excellent schema-driven
> configuration managers for XML, so you wouldn't have to edit the files
> by hand.

And that puts an additional requirement on developers, that each know how
to manually (and correctly) edit the schema file to ensure that new options
added are correctly specified.  You haven't eliminated complexity at all,
you've just shifted it to someone else.

Also, you're adding another tool in the chain that people must learn in order
to administer an Asterisk setup.  Right now, people can use whatever editor
they like, whether that's vim, emacs, nano, joe, or some other editor.  They
learn one editor tool and can use it generically for all purposes.  By adding
another requirement, you're increasing the barrier to entry, which is the
opposite direction that we want to go.

And finally, another person has already made the point that most XML editors
are graphical in nature.  A great many Asterisk installations are installed in
locations where a graphical front end is not practical.  Not only does that
mean that your options for text editors are limited, but they are unlikely to
be easy to use (or learn how to use), compared to full screen text editors,
which have been around for over 20 years and are fully mature software.

-- 
Tilghman