private static void RegisterDataTypes(DatabaseService ds)
        {
            ds.AddFieldDescriptor("username", new FieldDescriptor
                {
                    DataType = typeof(string),
                    MinLength = 5,
                    MaxLength = 30
                });
            ds.AddFieldDescriptor("nickname", new FieldDescriptor
                {
                    DataType = typeof(string),
                    MinLength = 5,
                    MaxLength = 30
                });
            ds.AddFieldDescriptor("password", new FieldDescriptor
                {
                    DataType = typeof(string),
                    MinLength = 8,
                    MaxLength = 30
                });
            ds.AddFieldDescriptor("role", new FieldDescriptor
                {
                    DataType = typeof(string),
                    MinLength = 8,
                    MaxLength = 30
                });

            ds.AddFieldDescriptor("timestamp", new FieldDescriptor
            {
                DataType = typeof(DateTime),
                MinLength = 8,
                MaxLength = 30
            });
            ds.AddFieldDescriptor("message", new FieldDescriptor
            {
                DataType = typeof(string),
                MinLength = 0,
                MaxLength = 16000
            });
            ds.AddFieldDescriptor("destination", new FieldDescriptor
                {
                    DataType = typeof(string),
                    MinLength = 10,
                    MaxLength = 10
                });
            ds.AddFieldDescriptor("messagetype", new FieldDescriptor
            {
                DataType = typeof(string),
                MinLength = 10,
                MaxLength = 10
            });
        }