I agree that it's simple thing to produce without using dedicated XML tools, but the character reservations that are involved with XML makes it potentially dangerous to do so. If you're willing to test, capture, and replace the characters (the minimum you should be doing is &, <, >, and %) in the data you're managing, that's fine, but the modules button all of that up for you nicely.

Here's how I'd do that. It's more code, granted, but it's always valid. Given the quality of some of the other tools that I've had to use that require XML, this will give me the best shot at not having to mess with it after I have it in production.

use strict;
use warnings;
use XML::Twig;

my $stream_id = 'stream-id';
my $event_name = 'event-name';
my $time_t = 'time-t';
my $filename = 'foo.xml';

my $twig = XML::Twig->new(pretty_print => 'record');
$twig->parse('<event/>');
my $root = $twig->root();
$root->insert_new_elt('stream-id' => $stream_id);
my $event_tag = $root->insert_new_elt('event-name' => $event_name);
my $primary_event_tag = $event_tag->insert_new_elt('primary-event');
$primary_event_tag->insert_new_elt('delete-time' => $time_t);
open(my $FH, '>', $filename);
$twig->flush(\*$FH);
close $FH;
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