I'm glad I was able to point you in the right direction.
Incidentally, you could also use DOM techniques to build up a gallery's XML file rather than just echoing the required output. Either would work fine.
If you plan to use PHP and want to use DOM techniques, then the following should get you started. You'll need to create loops for setting configuration options (as attributes to the opening <juiceboxgallery> tag) and for iterating over images (and also extract the relevant data from your source) but this should give you the required structure for a Juicebox gallery's XML file.
<?php
header('Content-Type: application/xml');
$dom_doc = new DOMDocument('1.0', 'UTF-8');
$dom_doc->formatOutput = true;
$settings_tag = $dom_doc->createElement('juiceboxgallery');
// Do this for each configuration option (loop)
// Need to define $key, $value
$settings_tag->setAttribute($key, $value);
// Do this for each image (loop)
// Need to define $image_url, $thumbnail_url, $link_url, $link_target, $image_title, $image_caption
$image_element = $dom_doc->createElement('image');
$image_element->setAttribute('imageURL', $image_url);
$image_element->setAttribute('thumbURL', $thumbnail_url);
$image_element->setAttribute('linkURL', $link_url);
$image_element->setAttribute('linkTarget', $link_target);
$title_element = $dom_doc->createElement('title');
$title_text = $dom_doc->createCDATASection($image_title);
$title_element->appendChild($title_text);
$image_element->appendChild($title_element);
$caption_element = $dom_doc->createElement('caption');
$caption_text = $dom_doc->createCDATASection($image_caption);
$caption_element->appendChild($caption_text);
$image_element->appendChild($caption_element);
$settings_tag->appendChild($image_element);
$dom_doc->appendChild($settings_tag);
echo $dom_doc->saveXML();
?>Now in the future if you could support reading JSON instead of or in addition to XML, then this would be terrific.
I do not know how likely this is to be implemented but I would certainly encourage you to post suggestions for future versions in the Feature Requests thread.
This keeps all the ideas together and ensures that they are not overlooked by the developers. Thank you.