/**
   * Create a new <code>ColladaRoot</code> for a {@link URL}.
   *
   * @param docSource the URL of the document.
   * @throws IllegalArgumentException if the document source is null.
   * @throws IOException if an error occurs while reading the Collada document.
   */
  public ColladaRoot(URL docSource) throws IOException {
    super(ColladaConstants.COLLADA_NAMESPACE);

    if (docSource == null) {
      String message = Logging.getMessage("nullValue.DocumentSourceIsNull");
      Logging.logger().severe(message);
      throw new IllegalArgumentException(message);
    }

    URLConnection conn = docSource.openConnection();
    this.colladaDoc = new ColladaInputStream(conn.getInputStream(), WWIO.makeURI(docSource));

    this.initialize();
  }