public bool SignIn(string jsonUserDetails)
        {
            Console.WriteLine("In SignIn...");

            try
            {
                UserTO  userTO = JsonConvert.DeserializeObject <UserTO>(jsonUserDetails);
                JObject jsonUserDetailsObject = JObject.Parse(jsonUserDetails);
                string  username = userTO.Username;
                string  password = userTO.Password;

                User userEntity = dbOperations.GetUserByUsername(username);

                if (userEntity != null)
                {
                    if (userEntity.Enabled && userEntity.Password.Equals(password))
                    {
                        userEntity.Connected = true;
                        userEntity.IP        = userTO.IP;
                        userEntity.Port      = userTO.Port;
                        connectedUsers.Add(username, userTO);
                        dbOperations.UpdateUser(userEntity, username);
                        dbOperations.AddFilesByUser(WCFServerUtils.FilesListByUser(userTO));
                        Console.WriteLine("SignIn succssfully");
                        return(true);
                    }
                    Console.WriteLine("The password {0} is incorrect for username {1}", password, username);
                }
                Console.WriteLine("User with username {0} no exist", username);
                return(false);
            }
            catch (JsonReaderException ex)
            {
                Console.WriteLine("jsonUserDetails is not a valid JSON format");
                Console.WriteLine(ex.StackTrace);
            }

            return(true);
        }