Mediatags-musicbrainz-example is a project mainly written in JavaScript, it's free.
Sends Request to musicbrainz database for artist Jaco Pastorius Gets back 200 (Resource retrieved successfully_
base url is musicbrainz.org/ws/1/ then add what you're looking for musicbrainz.org/ws/1/artist type=xml is necessary musicbrainz.org/ws/1/artist/?type=xml add artist name musicbrainz.org/ws/1/artist/?type=xml&name=jaco+pastorius