private void ReadID()
        {
            if (fingerprint == null || duration == -1) {
                // todo: timeout or sth?
                return;
            }

            string url = string.Format ("http://api.acoustid.org/v2/lookup?meta=recordings+releasegroups&format=xml&client={0}&duration={1}&fingerprint={2}", key, duration, fingerprint);
            var xmlReader = new XmlAcoustIDReader (url, completionHandler);
            xmlReader.ReadID ();
        }
        private void ReadID()
        {
            if (fingerprint == null || duration == -1)
            {
                // todo: timeout or sth?
                return;
            }

            string url       = string.Format("http://api.acoustid.org/v2/lookup?meta=recordings+releasegroups&format=xml&client={0}&duration={1}&fingerprint={2}", key, duration, fingerprint);
            var    xmlReader = new XmlAcoustIDReader(url, completionHandler);

            xmlReader.ReadID();
        }