AutoRefresh Entity Framework Data Using SQL Server Service Broker

<Window x:Class="MyChat.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:MyChat="clr-namespace:MyChat" Title="My Chat" Height="350" Width="525"
        >

    <Window.DataContext>

        <MyChat:MainViewModel x:Name="viewModel" />

    </Window.DataContext>

    <Grid>

        <Grid.RowDefinitions>

            <RowDefinition Height="200*" />

            <RowDefinition Height="Auto" />

            <RowDefinition Height="63*" />

        </Grid.RowDefinitions>

        <Grid.ColumnDefinitions>

            <ColumnDefinition Width="Auto" />

            <ColumnDefinition Width="268*" />

            <ColumnDefinition Width="117*" />

        </Grid.ColumnDefinitions>
        <TextBlock Grid.Row="1"
                     Name="textBlock1"
                     Text="Name"
                      TextAlignment="Right" />

        <TextBlock Grid.Row="2"
                      Name="textBlock2"
                      Text="Message"
                      TextAlignment="Right" />
        <TextBox Grid.Column="1"
                   Grid.Row="1"
                   Name="textBoxName"
                    Text="{Binding Path=Name}" />
        <TextBox Grid.Column="1"
                    Grid.Row="2"
                    Name="textBoxMessage"
                    Grid.ColumnSpan="2"
                    VerticalScrollBarVisibility="Auto"
                    Text="{Binding Path=Message}"
                    TextWrapping="WrapWithOverflow"
                    AcceptsReturn="True"
                    AcceptsTab="True" />

        <DataGrid Grid.ColumnSpan="3"
                     Name="dataGrid1"
                     AutoGenerateColumns="False"
                     ItemsSource="{Binding Path=Chat}">

            <DataGrid.Columns>

                <DataGridTextColumn Binding="{Binding Path=Date}"
                                       Header="Date" />

                <DataGridTextColumn Binding="{Binding Path=Name}"
                                       Header="Name" />

                <DataGridTextColumn Binding="{Binding Path=Message}"
                                       Header="Message" />

            </DataGrid.Columns>

        </DataGrid>

        <Button Content="Send"
                   Grid.Column="2"
                   Grid.Row="1"
                   Name="buttonSend"
                   Click="buttonSend_Click" />
    </Grid>
</Window>