How to get a Drupal 7 Services 3 custom resource to fire
You need to wrap your retrieve resource in an actions array:

function my_feed_services_resources() {

  $my_resource = array(
    'myresource' =&gt; array(
      'actions' =&gt; array(
        'retrieve' =&gt; array(
          'file' =&gt; array('type' =&gt; 'inc', 'module' =&gt; 'my_feed', 'name' =&gt; 'my_feed.services'),
          'callback' =&gt; '_myresource_retrieve',
          'help' =&gt; 'Lorem ipsum.',
          'args' =&gt; array(
            array(
              'name' =&gt; 'myparm',
              'optional' =&gt; TRUE,
              'source' =&gt; array('param'),
              'type' =&gt; 'string',
              'description' =&gt; 'Lorem ipsum',
            ),
          ),
        ),
      ),
    ),
  );

  return $my_resource;
}


You can then "fire" it by doing a POST to: ?q=[my-endpoint]/myresource/retrieve.json

Don't forget to attach the X-CSRF-Token header to your POST calls. Its value can be retrieved here: ?q=services/session/token