layer validation

<Window x:Class="BusinessLayerValidation.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="WPF IDataErrorInfo Sample" Width="350" Height="150"
        xmlns:src="clr-namespace:BusinessLayerValidation">
   
    <Window.Resources>
        <src:Person x:Key="data"/>

        <!--The tool tip for the TextBox to display the validation error message.-->
        <Style x:Key="textBoxInError" TargetType="TextBox">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type TextBox}">
                        <Grid Name="test">
                            <Border
                            BorderBrush="#d99"
                            BorderThickness="2" x:Name="bd">
                                <ScrollViewer Margin="0" x:Name="PART_ContentHost"/>
                            </Border>
                            <Border Name="ErrorImage"
                            Background="Red" HorizontalAlignment="Right">
                            </Border>
                        </Grid>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
            <Style.Triggers>
                <Trigger Property="Validation.HasError" Value="true">
                    <Setter Property="ToolTip"
                            Value="{Binding RelativeSource={x:Static RelativeSource.Self},
                        Path=(Validation.Errors)[0].ErrorContent}"/>                
                </Trigger>
            </Style.Triggers>
        </Style>
    </Window.Resources>

    <StackPanel Margin="20">
        <TextBlock>Enter your Name:</TextBlock>
        <TextBox Style="{StaticResource textBoxInError}">
            <TextBox.Text>
                <!-- Setting the ValidatesOnDataErrors to true enables to the Binding to check for
                    errors raised by the IDataErrorInfo implementation.
                    Alternatively, you can add DataErrorValidationRule to <Binding.ValidationRules/>-->
                <Binding Path="Name" Source="{StaticResource data}"
                         ValidatesOnDataErrors="True"  
                         UpdateSourceTrigger="PropertyChanged">
                    <Binding.ValidationRules>
                        <!-- Checks for exceptions during the setting of the source property.
                            Alternatively, set ValidatesOnExceptions to True on the Binding.-->
                        <ExceptionValidationRule/>
                    </Binding.ValidationRules>
                </Binding>
            </TextBox.Text>
        </TextBox>
        <TextBlock>Enter your age:</TextBlock>
        <TextBox Style="{StaticResource textBoxInError}">
            <TextBox.Text>
                <!-- Setting the ValidatesOnDataErrors to true enables to the Binding to check for
                    errors raised by the IDataErrorInfo implementation.
                    Alternatively, you can add DataErrorValidationRule to <Binding.ValidationRules/>-->
                <Binding Path="Age" Source="{StaticResource data}"
                         ValidatesOnDataErrors="True"  
                         UpdateSourceTrigger="PropertyChanged">
                    <Binding.ValidationRules>
                        <!-- Checks for exceptions during the setting of the source property.
                            Alternatively, set ValidatesOnExceptions to True on the Binding.-->
                        <ExceptionValidationRule/>
                    </Binding.ValidationRules>
                </Binding>
            </TextBox.Text>
        </TextBox>
    </StackPanel>
</Window>


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ComponentModel;

namespace BusinessLayerValidation
{
    public class Person : IDataErrorInfo
    {
        private int age;

        public int Age
        {
            get { return age; }
            set { age = value; }
        }

        public string Error
        {
            get
            {
                return null;
            }
        }

        private string name1;

        public string Name
        {
            get { return name1; }
            set { name1 = value; }
        }

       

        public string this[string name]
        {
            get
            {
                string result = null;

                if (name == "Age")
                {
                    if (this.age < 0 || this.age > 150)
                    {
                        result = "Age must not be less than 0 or greater than 150.";
                    }
                }
                if (name == "Name")
                {
                    if (this.name1 == string.Empty || this.name1 == null)
                    {
                        result = "Provide Name";
                    }
                }
                return result;
            }
        }
    }
}