Alternative web socket client interface. This interface is compliant with the W3C browser API for web sockets specified in http://dev.w3.org/html5/websockets/.

abstract class WebSocket {
  /**
   * Possible states of the connection.
   */
  static const int CONNECTING = 0;
  static const int OPEN = 1;
  static const int CLOSING = 2;
  static const int CLOSED = 3;

  /**
   * Create a new web socket connection. The URL supplied in [url]
   * must use the scheme [:ws:]. The [protocols] argument is either a
   * [:String:] or [:List<String>:] specifying the subprotocols the
   * client is willing to speak.
   */
  factory WebSocket(String url, [protocols]) => new _WebSocket(url, protocols);

  /**
   * Returns the current state of the connection.
   */
  int get readyState;

  /**
   * Returns the number of bytes currently buffered for transmission.
   */
  int get bufferedAmount;

  /**
   * Sets the callback to be called when a web socket connection has
   * been established.
   */
  void set onopen(void callback());

  /**
   * Sets the callback to be called when the web socket connection
   * encountered an error.
   */
  void set onerror(void callback(e));

  /**
   * Sets the callback to be called when the web socket connection is
   * closed.
   */
  void set onclose(void callback(CloseEvent event));

  /**
   * The extensions property is initially the empty string. After the
   * web socket connection is established this string reflects the
   * extensions used by the server.
   */
  String get extensions;

  /**
   * The protocol property is initially the empty string. After the
   * web socket connection is established the value is the subprotocol
   * selected by the server. If no subprotocol is negotiated the
   * value will remain [:null:].
   */
  String get protocol;

  /**
   * Closes the web socket connection.
   */
  void close(int code, String reason);

  /**
   * Sets the callback to be called when a message have been
   * received.
   */
  void set onmessage(void callback(MessageEvent event));

  /**
   * Sends data on the web socket connection. The data in [data] must
   * be either a [:String:] or [:List<int>:] holding bytes.
   */
  void send(data);
}