/----------------------------------------------------\
         | Generating and Parsing XML with Perl -- A Tutorial |
         |   (C)2001-2004 Adam Monsen <adamm@wazamatta.com>   |
         \----------------------------------------------------/

Perl is well-suited for XML manipulation. Here's one way to generate
and retrieve information from XML.

--BEGIN xml_gen.pl--------------------------------
#!/usr/bin/perl -w
use XML::Generator;
use strict;

my $xml = XML::Generator->new(':pretty');

print $xml->xmldecl();
print $xml->DataTribe(
       $xml->SendFunc(
         $xml->AcknowledgeAddrs(
           $xml->EmailAddress('amonsen@example.com'),
           $xml->EmailAddress('meonkeys@hotmail.com'),
         ),
         $xml->ClientName('MarketSuckemdry & Buy, INC.'),
         $xml->ImportData(
           $xml->Row(
             $xml->UserID('0157H7'),
             $xml->Column({ Name => 'Car'}, 'Honda'),
             $xml->Column({ Name => 'Sex'}, 'Female'),
           ),
         ),
       ),
);
print "\n";
--END   xml_gen.pl--------------------------------

Close all your parens properly and you're guaranteed well-formed XML!
This is basically a compile-time check for well-formedness.
XML::Generator also has easy ways to handle namespaces, CDATA,
comments, <!DOCTYPE... declarations, etc.

Here's the output of the above xml_gen.pl:
--BEGIN xml_gen.pl output-------------------------
<?xml version="1.0" standalone="yes"?>
<DataTribe>
  <SendFunc>
    <AcknowledgeAddrs>
      <EmailAddress>amonsen@example.com</EmailAddress>
      <EmailAddress>meonkeys@hotmail.com</EmailAddress>
    </AcknowledgeAddrs>
    <ClientName>MarketSuckemdry &amp; Buy, INC.</ClientName>
    <ImportData>
      <Row>
        <UserID>0157H7</UserID>
        <Column Name="Car">Honda</Column>
        <Column Name="Sex">Female</Column>
      </Row>
    </ImportData>
  </SendFunc>
</DataTribe>
--END   xml_gen.pl output-------------------------

For checking XML validity against a DTD, I use nsgmls. I don't know an
easy way to validate XML with Perl.

For Retrieving data, XML::XPath is a great way to get at a specific
piece of data. I ran this script on the output of xml_gen.pl...
--BEGIN xpath.pl----------------------------------
#!/usr/bin/perl -w

use XML::XPath;
use XML::XPath::XMLParser;
use strict;

my $xpath = XML::XPath->new(ioref => \*STDIN);
my $clientname = $xpath->find('/DataTribe/SendFunc/ClientName/text()');
print "Client is $clientname for this transaction\n";
--END   xpath.pl----------------------------------

And here is the result.
--BEGIN xpath.pl output---------------------------
Client is MarketSuckemdry & Buy, INC. for this transaction
--END   xpath.pl output---------------------------

Notice how the amperstand was conveniently un-escaped. Good luck!
-Adam

            /---------------------------------------------\
            | v0.01 [ Mon Nov 26 19:23:37 PST 2001 ]      |
            |   -initial revision                         |
            | v0.02 [ Sun Feb 10 17:20:12 PST 2002 ]      |
            |   -simplified XML::XPath test (thanks Steve |
            |    Grazzini!)                               |
            |   -now in unix format                       |
            |   -fixed some typos                         |
            | v0.03 [ Sun Apr 13 13:06:02 PDT 2003 ]      |
            |   -added xml declaration                    |
            | v0.04 [ Sat Mar 20 11:34:59 PST 2004 ]      |
            |   -update for XML::Generator v0.98, which   |
            |    includes a ':pretty' option (thanks      |
            |    Benjamin Holzman!)                       |
            \---------------------------------------------/