private void DuplexSample(string s)
        {
            if (String.IsNullOrEmpty(s))
            {
                throw new ArgumentNullException();
            }

            EndpointAddress address = new EndpointAddress(addressDuplex);

            var clientCallback = new UpisiCallback();
            var context        = new InstanceContext(clientCallback);

            var factory = new DuplexChannelFactory <IUpisi>(clientCallback, binding, address);

            IUpisi messageChanel = factory.CreateChannel();

            Task.Run(() => messageChanel.PosaljiInsert(s));
        }
        private static void DuplexSample()
        {
            //"INSERT INTO UneseneVrednosti " +
            //"(IDGeoPodrucja, VremeMerenja, Vrednost) " +
            //"VALUES ('" + idGeoPodrucja + "', '" + datum + "', " + _unesenaPotrosnja + ")";

            string s       = "INSERT INTO UneseneVrednosti(IDGeoPodrucja, VremeMerenja, Vrednost) VALUES ('DO', '2018-6-1 00:30:00.000', 234)";
            var    binding = new NetTcpBinding();
            var    address = new EndpointAddress("net.tcp://localhost:10101/IUpisi");

            var clientCallback = new UpisiCallback();
            var context        = new InstanceContext(clientCallback);

            var factory = new DuplexChannelFactory <IUpisi>(clientCallback, binding, address);

            IUpisi messageChanel = factory.CreateChannel();

            Task.Run(() => messageChanel.PosaljiInsert(s));
        }