HELP: Integrating WP with raw PHP code once published button is hit

If you want to trigger some action when a post is published or edited, you can have a look at the save_post and edit_post actions.

You could easily hook in the edition process, modify your post data if needed, and save it again.

function myplugin_save_post($post_id, $post) {
  // $post contains the post itself
  // so you can check the submitted data and see if you need to update it
  // $post->post_title is what you are looking for
  // call your script to get the music data
  // save the data in the wp_postmeta table so you can retrieve it later
}
add_action('edit_post', 'myplugin_save_post', 10, 2);
add_action('save_post', 'myplugin_save_post', 10, 2);