/**
     * Performs a query based on the parameters
     * supplied in the TrackFilter object. Returns 
     * an array of possible matches with scores, as 
     * returned by the musicBrainz XML web service.
     * Note that these types of queries only return some 
     * information, and not all the information available
     * about a particular track is available using
     * this type of query. You will need to get the
     * MusicBrainz id (mbid) and perform a lookup with
     * getTrack to return complete information about 
     * a release. This method returns an array of 
     * Track objects that are possible matches.
     *
     * @param phpBrainz_TrackFilter $trackFilterObj
     * @return array
     */
    public function findTrack(phpBrainz_TrackFilter $trackFilterObj)
    {
        if (sizeof($trackFilterObj->createParameters()) < 1) {
            throw new Exception('The release filter object needs 
	        at least 1 argument to create a query.');
        }
        $queryStr = TRACK_URL . "?type=xml";
        $args = $trackFilterObj->createParameters();
        foreach ($args as $key => $value) {
            $args[$key] = utf8_encode($value);
        }
        $queryStr .= "&" . http_build_query($args);
        $xml = simplexml_load_file($queryStr);
        if ($xml === false) {
            throw new Exception("Unable to load XML file. URL: " . $url);
        }
        $tracks = array();
        foreach ($xml->{'track-list'}->track as $track) {
            # Must specify the namespace
            $attrNS = $track->attributes("http://musicbrainz.org/ns/ext-1.0#");
            $trackRels = array();
            foreach ($track->{'release-list'}->release as $release) {
                $trackRels[] = $this->parseReleaseXML($release);
            }
            $newTrack = $this->parseTrackXML($track);
            $tracks[] = $newTrack;
        }
        return $tracks;
    }
 /**
  * Performs a query based on the parameters
  * supplied in the TrackFilter object. Returns 
  * an array of possible matches with scores, as 
  * returned by the musicBrainz XML web service.
  * Note that these types of queries only return some 
  * information, and not all the information available
  * about a particular track is available using
  * this type of query. You will need to get the
  * MusicBrainz id (mbid) and perform a lookup with
  * getTrack to return complete information about 
  * a release. This method returns an array of 
  * Track objects that are possible matches.
  *
  * @param phpBrainz_TrackFilter $trackFilterObj
  * @return array
  */
 public function findTrack(phpBrainz_TrackFilter $trackFilterObj)
 {
     if (sizeof($trackFilterObj->createParameters()) < 1) {
         die(print "At least one argument must be supplied to performa a query.");
     }
     $queryStr = TRACK_URL . "?type=xml";
     $args = $trackFilterObj->createParameters();
     foreach ($args as $key => $value) {
         $queryStr .= "&" . $key . "=" . urlencode($value);
     }
     $xml = simplexml_load_file($queryStr);
     $tracks = array();
     foreach ($xml->{'track-list'}->track as $track) {
         $attrNS = $track->attributes("http://musicbrainz.org/ns/ext-1.0#");
         $trackRels = array();
         foreach ($track->{'release-list'}->release as $release) {
             $trackRels[] = $this->parseReleaseXML($release);
         }
         $newTrack = $this->parseTrackXML($track);
         $tracks[] = $newTrack;
     }
     return $tracks;
 }