use strict;
use warnings;

use XML::LibXML               qw( );
use XML::LibXML::XPathContext qw( );

( my $file = $0 ) =~ s/\.pl\z/.xml/i;

my $parser = XML::LibXML->new ();
my $dom    = $parser->load_xml( location => $file );
my $root   = $dom->getDocumentElement();
my $xpc    = XML::LibXML::XPathContext->new($root);

$xpc->registerNs(
    p => 'http://www.somedomain.tld/market_reg/admin_server/1.0' );

for my $node ( $xpc->findnodes('//p:request/*/p:action') ) {
    print $node->textContent(), "\n";
}

##</code><code>##

START
STOP
GET_INFO

##</code><code>##

use strict;
use warnings;

use XML::LibXML               qw( );
use XML::LibXML::XPathContext qw( );

( my $file = $0 ) =~ s/\.pl\z/.xml/i;

my $parser = XML::LibXML->new ();
my $dom    = $parser->load_xml( location => $file );
my $root   = $dom->getDocumentElement();
my $xpc    = XML::LibXML::XPathContext->new($root);

$xpc->registerNs(
    p => 'http://www.somedomain.tld/market_reg/admin_server/1.0' );

for my $req_node ( $xpc->findnodes('//p:request') ) {
    for my $action_node ( $xpc->findnodes('*/p:action', $req_node) ) {
        print $action_node->textContent(), "\n";
    }
}