WPF(Binding of ObjectDataProvider)

<Window x:Class="TestOfObjectDataProvider.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<StackPanel Background="LightBlue">
<TextBox x:Name="testBoxArg1" Margin="5" />
<TextBox x:Name="testBoxArg2" Margin="5" />
<TextBox x:Name="textBoxResult" Margin="5" />
</StackPanel>
</Window>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace TestOfObjectDataProvider
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
this.SetBinding();
}

private void SetBinding()
{
ObjectDataProvider odp = new ObjectDataProvider();
odp.ObjectInstance = new Calculator();
odp.MethodName = "Add";
odp.MethodParameters.Add("");
odp.MethodParameters.Add("");

Binding bindingToArg1 = new Binding("MethodParameters[0]")
{
Source = odp,
BindsDirectlyToSource = true,
UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged
};

Binding bindingToArg2 = new Binding("MethodParameters[1]")
{
Source = odp,
BindsDirectlyToSource = true,
UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged
};

Binding bindingToResult = new Binding(".")
{
Source = odp
};

this.testBoxArg1.SetBinding(TextBox.TextProperty, bindingToArg1);
this.testBoxArg2.SetBinding(TextBox.TextProperty, bindingToArg2);
this.textBoxResult.SetBinding(TextBox.TextProperty, bindingToResult);

}
}

public class Calculator
{
public string Add(string args1, string args2)
{
double x = 0;
double y = 0;
double z = 0;
if(double.TryParse(args1, out x) && double.TryParse(args2, out y))
{
z = x + y;
return z.ToString();
}
return "Input Error!";
}
}

}