public FacebookRESTClient(string apiKey, string apiSecret, string sessionKey, string sessionSecret)
        {
            // Note: use ApiSecret as the sessionSecret with web apps, desktop apps would use the SessionSecret

            channel = ChannelHelper.BuildChannel();

            this.apiKey        = apiKey;
            this.apiSecret     = apiSecret;
            this.sessionKey    = sessionKey;
            this.sessionSecret = sessionSecret;
        }