/// <summary>
        /// Devuelve todos los datos
        /// </summary>
        /// <returns>ServerResponseRol</returns>
        public ServerResponseRol GetAll()
        {
            ServerResponseRol serverResponseRol;

            try
            {
                OauthToken oauthToken = ServerService.obtenerToken();

                if (null != oauthToken)
                {
                    var url = Constantes.SERVIDOR + ROL + "all";

                    var httpRequest = (HttpWebRequest)WebRequest.Create(url);
                    httpRequest.Method = "GET";

                    httpRequest.Accept = "application/json";
                    httpRequest.Headers["Authorization"] = "Bearer " + oauthToken.access_token;

                    var httpResponse = (HttpWebResponse)httpRequest.GetResponse();
                    using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
                    {
                        var result = streamReader.ReadToEnd();

                        serverResponseRol = JsonSerializer.Deserialize <ServerResponseRol>(result);
                    }

                    //Console.WriteLine(httpResponse.StatusCode);
                }
                else
                {
                    serverResponseRol = new ServerResponseRol();

                    ErrorBean error = new ErrorBean();
                    error.code    = MessageExceptions.SERVER_ERROR;
                    error.message = MessageExceptions.MSSG_SERVER_ERROR;

                    serverResponseRol.error = error;
                }
            }
            catch (System.Exception)
            {
                serverResponseRol = new ServerResponseRol();

                ErrorBean error = new ErrorBean();
                error.code    = MessageExceptions.SERVER_ERROR;
                error.message = MessageExceptions.MSSG_SERVER_ERROR;

                serverResponseRol.error = error;
            }

            return(serverResponseRol);
        }
        public void cargaCombo()
        {
            if (null == _listaRol)
            {
                Thread t = new Thread(new ThreadStart(() =>
                {
                    observableCollectionRol.Add("Seleccionar");

                    ServerServiceRol serverServiceRol   = new ServerServiceRol();
                    ServerResponseRol serverResponseRol = serverServiceRol.GetAll();

                    if (200 == serverResponseRol.error.code)
                    {
                        _listaRol = serverResponseRol.listaRol;

                        foreach (var item in serverResponseRol.listaRol)
                        {
                            observableCollectionRol.Add(item.nombre);
                        }
                    }
                    else
                    {
                        observableCollectionRol.Add("Seleccionar");
                    }
                }));

                t.Start();
            }
            else
            {
                observableCollectionRol.Add("Seleccionar");

                foreach (var item in _listaRol)
                {
                    observableCollectionRol.Add(item.nombre);
                }
            }
        }