This is to implement a service endpoint for returning the daily featured picture from Commons.
Commons provides an RSS feed of the picture of the day:
https://commons.wikimedia.org/w/api.php?action=featuredfeed&feed=potd&feedformat=rss&language=en
Unfortunately, it doesn't look like the feed provides a well-structured link to the actual File page of the picture! So, it would still need to be scraped from within the `<description>` text. :(
Update: I've found a [[ http://stackoverflow.com/a/9091612/67808 | SO answer ]] that makes //excellent// use of the API to fetch the actual File name of the featured picture (by directly invoking the template)!
Here it is, adapted a bit (just replace the date in the template):
https://commons.wikimedia.org/w/api.php?action=expandtemplates&prop=wikitext&text={{Potd/2016-04-15}}