Matt Sergeant writes:
> > This assumes you need XML in the first place.
>
> No, it does not. The rest of my post spoke about XML as a
> data format and set of tools, not as a syntax. Please stop
> thinking about XML as syntax!!
If my entire system is written in Perl, why do I need XML as a data
format? Perl's data structures are richer and have much more support
in Perl than XML has in any language. Perl has been around much
longer and is full-fledged programming language. It has better
tools. It's got a larger community.
> You seem to speak as someone who has never tried by the sounds of
> things. This is one of the things AxKit's XSP taglibs are designed
> to provide for.
I've never used XSP. I have used XSLT, tried to use XSD, and am
currently mired in DocBook/XML. One of my sites generates XML for its
data export format.
Let's take an XSP example from axkit.org:
<xsp:structure>
<xsp:include>Time::Object</xsp:include>
</xsp:structure>
<xsp:logic><![CDATA[
sub mytime {
my ($time) = @_;
$time ||= time;
return Time::Object->new($time);
}
]]></xsp:logic>
Why is the above better than below? (I cleaned up the perl :-)
use Time::Object;
sub mytime {
my ($time) = @_;
return Time::Object->new($time || time);
}
Or, why can't I just call Time::Object->new where I need it?
When I first started working with DocBook/XML, I thought there were
all these great tools. When I tried to install dblite, it took me two
hours and it still didn't work. I had to install a particular version
of Java for the XSLT program. Fortunately, Perl was already
installed, which dblite uses for glue. The *.xslt files have to be
configured to be found by the XSLT program. And on and on it went.
I said to myself, "Self, this is a trivial problem. Let's see how
long it takes me to hack something in Perl." Two hours later
I had a working DocBook/XML to HTML translator, which was good enough
for my needs.
Later I decided to make this into an example program. This new
program processes about 50 different DocBook/XML tags and includes a
word counter for XML files. It is 340 lines including comments and
POD. Source: http://petshop.bivio.biz/src?s=Bivio::XML::DocBook
Compare this to dblite which has 5400 lines of XSLT in 6 files and
about 3000 lines of Perl to glue it all together. This doesn't
include Sax or Xalan, which are the java programs you need to run
XSLT.
XML solves a problem through an indirection. It's very similar to
CORBA IDL in that it is a language which is used as a least common
denominator between heterogeneous languages/systems. This is a good
use for XML. (BTW, if you look at the committees from the OMG and the
committees in the XML world, you'll see a surprising overlap. I
wonder if they'll be successful this time.)
While every software problem can be solved through another layer of
indirection, every layer of indirection also creates a new software
problem.
Rob
