HTTP server.

abstract class HttpServer {
  factory HttpServer() => new _HttpServer();

  /**
   * Start listening for HTTP requests on the specified [host] and
   * [port]. If a [port] of 0 is specified the server will choose an
   * ephemeral port. The optional argument [backlog] can be used to
   * specify the listen backlog for the underlying OS listen
   * setup. See [addRequestHandler] and [defaultRequestHandler] for
   * information on how incoming HTTP requests are handled.
   */
  void listen(String host, int port, [int backlog]);

  /**
   * Attach the HTTP server to an existing [:ServerSocket:]. If the
   * [HttpServer] is closed, the [HttpServer] will just detach itself,
   * and not close [serverSocket].
   */
  void listenOn(ServerSocket serverSocket);

  /**
   * Adds a request handler to the list of request handlers. The
   * function [matcher] is called with the request and must return
   * [:true:] if the [handler] should handle the request. The first
   * handler for which [matcher] returns [:true:] will be handed the
   * request.
   */
  addRequestHandler(bool matcher(HttpRequest request),
                    void handler(HttpRequest request, HttpResponse response));

  /**
   * Sets the default request handler. This request handler will be
   * called if none of the request handlers registered by
   * [addRequestHandler] matches the current request. If no default
   * request handler is set the server will just respond with status
   * code [:NOT_FOUND:] (404).
   */
  void set defaultRequestHandler(
      void handler(HttpRequest request, HttpResponse response));

  /**
   * Stop server listening.
   */
  void close();

  /**
   * Returns the port that the server is listening on. This can be
   * used to get the actual port used when a value of 0 for [port] is
   * specified in the [listen] call.
   */
  int get port;

  /**
   * Sets the error handler that is called when a connection error occurs.
   */
  void set onError(void callback(e));

  /**
   * Set the timeout, in seconds, for sessions of this HTTP server. Default
   * is 20 minutes.
   */
  int set sessionTimeout(int timeout);
}