Silverlight Navigation Project (VS2008) – Question

Silverlight-Navigation-Project

Silverlight-Navigation-Project


I have created a minimal project to illustrate the problem. I am using VS2008 SP1 and Silverlight 3.

I created a Silverlight Navigation Project, Added a Product Model, A SingleProductView, and a ProductViewModel.

I added 2 new Pages Review.xaml and Cart.xaml.

Review.xaml uses the SingleProductView to display the product details and an [add to cart] button which when clicked should add the product to the Shopping Cart and then navigate to the Cart.xaml page.

The problem I have is in the SingleViewModel.

The SingleViewModel contains a button (btnAddToCart), which should add the product details to the cart (will be a database populated using a web service call) and then it should navigate to the Cart Page (Cart.xaml)


<UserControl x:Class="SL3NavTest01.SingleProductView"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    xmlns:local="clr-namespace:SL3NavTest01"
    xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
    d:DesignWidth="950" d:DesignHeight="800">
    <Grid x:Name="LayoutRoot" Background="White">
        <StackPanel Orientation="Horizontal" VerticalAlignment="Top">
            <Image   Source="/SL3NavTest01;Component/Assets/Images/VS2010Ultimate.jpg" Stretch="None" Height="200" Width="200"
											HorizontalAlignment="Center" VerticalAlignment="Center"/>
            <StackPanel Margin="20,0,0,0">
                <TextBlock Text="{Binding Name, Mode=TwoWay}" TextWrapping="Wrap" Margin="0,30,40,0"
									FontFamily="Verdana" FontSize="18" Foreground="Black" FontWeight="Bold" />
                <StackPanel Orientation="Horizontal" Margin="0,30,0,0">
                    <TextBlock Text="Price: " FontFamily="Verdana" FontSize="16"
										Foreground="Black" FontWeight="Normal" />
                    <TextBlock Text="{Binding Price, Mode=TwoWay}"
										FontFamily="Verdana" FontSize="16" Foreground="Black" FontWeight="Normal" />
                </StackPanel>
                    <Button x:Name="btnAddToCart" Width="75" Margin="0,30,0,0" Content="Add To Cart"
                     Click="btnAddToCart_Click"/>
            </StackPanel>
        </StackPanel>
    </Grid>
</UserControl>


Imports System.Windows.Browser
Partial Public Class SingleProductView
    Inherits UserControl

    Public Sub New()
        InitializeComponent()
    End Sub

    Private Sub btnAddToCart_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
        '
        '   The project has been simplified so as to only include the structure and context of where the
        '   problem exists.
        '
        '
        '   On clicking this button the code should:
        '
        '   1.  Add Product to Shopping Cart (via Web Service)
        '   2.  Then navigate to the Shopping Cart Page (\views\Cart.xaml)
        '
        '
        '   Code to add product to shopping cart (I can do this part!)
        '   ----------------------------------------------------------
        '
        '
        '
        '   Code to navigate to Cart.xaml (This is the problem!!!)
        '   ------------------------------------------------------
        '
        '
        '
        '   I can't find a syntax that would do the equivalent of the following:
        '   ContentFrame.Navigate(New Uri("/Cart", UriKind.Relative))
        '
        '   This is my solution:
        '   I know the view is used on the "Review" page and I want to navigate to the "Cart" page.
        '   Also required Imports System.Windows.Browser
        '
        Dim strNav As String = HtmlPage.Document.DocumentUri.ToString
        strNav = Replace(strNav, "Review", "Cart")
        HtmlPage.Window.Navigate(New Uri(strNav, UriKind.Absolute))
        '
        '   It may be that I should use a Hyperlink button, but I am uncertain as to how I would be able
        '   to Add the Product to the Shopping Cart first then Navigate to the Cart.xaml Page.
        '
        '   I realize that this is not stricly MVVM, but I am looking to get the simple solution working
        '   first.
        '
        '   Feel free to provide references to the "correct/best practice" way to do this.
        ''
    End Sub
End Class

Found this thread
http://forums.silverlight.net/forums/t/2684.aspx
which has been read 99,870+ times (may suggest the tiniest of gaps in silverlight functionality or documentation).

My solution is as follows:

        Dim strNav As String = HtmlPage.Document.DocumentUri.ToString
        strNav = Replace(strNav, “Review”, “Cart”)
        HtmlPage.Window.Navigate(New Uri(strNav, UriKind.Absolute))

requires

Imports System.Windows.Browser

I have attached the original simplified project solution zip file so that you can try out various solutions

 SL3NavTest01.zip

Download SL3NavTest01.zip.doc and rename to SL3NavTest01.zip and see what you can come up with.

SL3NavTest01TestPage.html should be used as the start page.

The Luddite Developer.

Scott Hanselman and Daniel Crenna (aka Dimebrain) advise NBC that all they need for Monday Night Football is a Vado or a Flip Mino

OK this is just a bit of fun as I respect the work that these guys do and the information they put out there for we poor mortals.

Scott Hanselman Vado

Dimebrain-Flip

I have been traveling around the country over the summer taking videos of my son at his various track meets.  I created a website and decided to add a video gallery using silverlight.  The intention was to provide a similer experience as provided by the BBC iPlayer.  In particular, I wanted viewers to be able to view the videos in Full Screen mode with one click.  I use a Panasonic SDR-S15 Camcorder, Sony Vegas Movie Studio to edit and Expression 3 to Encode at 1Mb/s.

Iam sure that the Vado HD and the Flip Mino HD perform really well in the environments used by both Scott and Daniel, but it really is a matter of horses for courses.

The Panasonic is a great little camera, lightweight, SDHC memory, and most importantly for me 10 x optical zoom.  When editing these videos and encoding them for the web one very quickly realises that if you do not have the desired quality on the original then you are not going to get the desired results on the end product.  If you check the Video Gallery then you will notice that the movies get better over time as I learn more.  Most importantly, use a tripod for these high zoom shots.

My next camera will definitely be HD and I will look to get better than 10 x zoom.  I am afraid that I can envisage an $1100 camera (UK prices really suck by the way) and I am absolutely certain that NBC will be paying a lot more than $1100 for the cameras that they use for Monday Night Football.

My point is, do not let Scott and Daniel talk you out of getting the camera you need.  If you need a Smith & Wesson 45, the most powerful hand camcorder ever made then make your day.

Silverlight, WCF, Security And Things You Might Not Know

Silverlight-Security-WCF

On 24-Jul-2009, I wrote an article entitled Where are the guides to Security Best Practices in Silverlight? , and followed this up with an article entitled Silverlight Security – Part One – Code Obfuscation.  Since then of I have been keeping an eye open for any new articles that tackled this very important subject.

Today, I found an article by Robbe Morris over at eggheadcafe.com entitled Silverlight, WCF, Security And Things You Might Not Know.

This article covers many of the security steps that you will want to implement in any Silverlight / WCF application.

Have you got lost in the maze of tutorials available for Silverlight and WPF?

Silverlight Confusion

Silverlight Confusion

 

I was looking for a tool that would allow me to organize links to all the articles that I have read.

I would like to add notes about each of the articles to tell me what important feature or technique is being explained. The notes would also tell me where to find the projects I installed or implemented on my own development systems.

I would also like to be able to index the articles by tags and categories and order the articles, videos, or tutorials in a way that will help me learn the subject in detail without missing anything out. Maybe something like a learning tree.

So for instance in Silverlight, you may have:

Silverlight Tutorial Part 1 (of 8): Creating “Hello World” with Silverlight 2 and VS 2008 by Scott Guthrie, here.

Find on my computer here:
C:\Documents and Settings\Luddite\My Documents\Visual Studio 2008\Projects\Silverlight\MSDiggSample_VB

Jesse Liberty has started Project Turing, here.

This project uses RIA Services which is currently in beta, I will want to come back to this when RIA Services has been officially released.

Brad Abrams has a series on BusinessApps for Silverlight 3 RTM and .NET RIA Services (and now Azure), here.

The articles are numerous and varied and some way of keeping things up to date, allowing you to replace articles that have become obsolete, or replace articles which you have found to do a better job.

Can anyone recommend a good product that would help with this.

Scot Hanselman recommends Evernote, not for this, but I was wondering if something like Evernote would fit the bill…

Using the Background Worker Process for Long Running Processes in WPF and Silverlight

Using the Background Worker Process for Long Running Processes in WPF and Silverlight

Using the Background Worker Process for Long Running Processes in WPF and Silverlight

In a previous article WPF DataBinding using Visual Basic (VB.NET), a problem was encountered when trying to keep the User Interface active during Long Running Processes as a result of a button click.  Either the whole system would hang until the process was completed or the program would crash.

This hang-up is due to the fact that both the Long Running Process and the UI are using the same thread.  The solution is to run the Long Running Process in a separate thread.  The BackgroundWorker component, gives you the ability to execute Long Running Processes in the background asynchronously, on a separate thread from the application’s main UI thread.

I have just started a project which is going to have quite a few of these Long Running Processes and so what I need is a simple implementation of the Background Worker  process which I can expand as required.

The implementation consists of a WPF page with a start button, a cancel button and three labels to let the user know what is happening before, during and after the Long Running Process has been started by the start button.


<Page x:Class="BackGroundWorkerExample"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="BackGroundWorkerExample"
    x:Name="BackGroundWorkerExample"  WindowTitle="WPF Luddite Test Bed: Background Worker Example" Width="1024" Height="768">
    <StackPanel>
        <Button x:Name="btnStartBackgroundProcess" Width="300" Height="30" Margin="0 20 0 0"
            Content="Start Background Process">
        </Button>
        <Label x:Name="lblStartedCompleted" Content="" Width="500" Height="30" Margin="0 20 0 0">
        </Label>
        <Label x:Name="lblCounter" Content="" Width="500" Height="30" Margin="0 20 0 0">
        </Label>
        <Label x:Name="lblPercentCompleted" Content="" Width="500" Height="30" Margin="0 20 0 0">
        </Label>
        <Button x:Name="btnCancelBackgroundProcess" Width="300" Height="30" Margin="0 20 0 0"
            Content="Cancel Background Process" IsEnabled="False">
        </Button>

    </StackPanel>
</Page>

The following steps will be required in the code behind:

1.  Define a new BackgroundWorker, create an instance and do some setup.

2. Define the LongRunningProcess – must not reference the User Interface (UI).

3. Define a subroutine to handle the BackgroundWorker DoWork event.

4. Define a subroutine to handle the BackgroundWorker ProgressChanged event.

5. Define a subroutine to handle the BackgroundWorker RunWorkerCompleted event.

6. Define a subroutine to handle the event caused by the Start button being clicked.

7. Define a subroutine to handle the event caused by the Cancel button being clicked.


Imports System.ComponentModel

Partial Public Class BackGroundWorkerExample

    '
    '   Define a new backgroung worker.
    '
    Private WithEvents bw As New BackgroundWorker()
    '
    ' Create new instance of BackGroundWorker and do some setup
    '
    Public Sub New()

        InitializeComponent()

        bw.WorkerSupportsCancellation = True
        bw.WorkerReportsProgress = True

    End Sub

    Private Function LongRunningProcess() As String
        '
        '   The LongRunngProcess should NOT refer to any UI objects.
        '
        Dim iteration As Integer = CInt(100000000 / 100)
        Dim cnt As Long = 0

        For i As Long = 0 To 100000000
            '
            '   Bring the LongRunningProcess to an orderly termination if the Cancel button is clicked.
            '   - see further comments in routine that handles the btnCancelBackgroundProcess_Click event.
            '
            If bw.CancellationPending Then
                Return ""
            End If

            cnt = cnt + 1

            '
            '   Report Progress:
            '   When you need the background operation to report on its progress,
            '   you can call the ReportProgress method to raise the ProgressChanged event.
            '   The ReportProgress Method permits up to 2 parameters (ProgressChangedEventArgs):
            '       Paramater 1. Is of type Integer and is defined as "percentProgress"
            '       Paremeter 2. Is of type Object and is defined as "userState"
            '       I see no reason why you can't return any information you want as long as you conform to the
            '       parameter types integer and object.
            '
            '   In a simple example like this, if the ReportProgress method was called for every iteration of i
            '   then the system would probably hang the user interface and run out of memory. Therefore, in this instance, we
            '   only report back on every 10,000 iterations.
            '
            If (i Mod 10000 = 0) _
                And (bw IsNot Nothing) _
                AndAlso bw.WorkerReportsProgress Then
                '
                '   Call ReportProgress
                '
                bw.ReportProgress(i \ iteration, cnt)
            End If

        Next

        Return cnt.ToString()

    End Function

    Private Sub backgroundWorker_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs) Handles bw.DoWork
        '
        ' call long running process and get result
        '
        e.Result = Me.LongRunningProcess()
        '
        ' Cancel if cancel button was clicked.
        '
        If bw.CancellationPending Then
            e.Cancel = True ' This sets the Cancelled property of the RunWorkerCompletedEventArgs
            Return
        End If

    End Sub

    Private Sub backgroundWorker_ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles bw.ProgressChanged
        '
        '   Use the ProgressChanged Sub to give user feedback via the UI.
        '
        ' Update UI with values contained in ProgressChangedEventArgs e.ProgressPercentage and e.UserState.
        '
        Me.lblPercentCompleted.Content = CStr(e.ProgressPercentage) & "% Completed."
        lblCounter.Content = CStr(e.UserState)
        ''
    End Sub

    Private Sub backgroundWorker_RunWorkerCompleted(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs) Handles bw.RunWorkerCompleted
        '
        ' Back on primary thread, can access ui controls
        '
        If e.Cancelled Then
            Me.lblStartedCompleted.Content = "Process Cancelled."
        Else
            Me.lblStartedCompleted.Content = "Background Process Completed. "
        End If
        '
        Me.btnStartBackgroundProcess.IsEnabled = True
        Me.btnCancelBackgroundProcess.IsEnabled = False
        ''
    End Sub

    Private Sub btnStartBackgroundProcess_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles btnStartBackgroundProcess.Click
        '
        lblStartedCompleted.Content = "Background Process Started..."
        Me.btnStartBackgroundProcess.IsEnabled = False
        Me.btnCancelBackgroundProcess.IsEnabled = True
        '
        ' Calls DoWork on secondary thread
        '
        bw.RunWorkerAsync()
        '
        ' RunWorkerAsync returns immediately.
        ''
    End Sub

    Private Sub btnCancelBackgroundProcess_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles btnCancelBackgroundProcess.Click
        '
        '   There are several points to note when cancelling a process:
        '
        '   1. The WorkerSupportsCancellation property must have been initialised to true.
        '
        '   2. The CancelAsync method does not immediately cancel the process, but instead sets the
        '      CancellationPending property to True.  It is the therefore important that the LongRunningProcess
        '      periodically checks the CancellationPending property and if True the process should be
        '      terminated in an orderly manner.
        '
        '   3. The CancellationPending property of the background worker process should also be checked by the
        '      routine handling the DoWork method after the LongRunningProcess has completed.
        '      If the CancellationPending Property is true then the DoWork routine should set Cancel
        '      property of the DoWorkEventArgs to True.
        '      CancelAsync() method.  This should be checked by the routine which is handling the RunWorkerCompleted
        '      event.
        '
        '   4. It is good practice to ensure theat the Cancel button is only enabled when the LongRunningProcess
        '      is actually running.  Therefore the button should be disabled by default, only enabled when the
        '      process is started, and disable again when the process is completed or cancelled.
        '
        bw.CancelAsync()
        '
        btnCancelBackgroundProcess.IsEnabled = False
        '
    End Sub

End Class

Hope this helps.

Expression 3 Upgrade Offer for Visual Studio Silverlight and WPF Developers

Expression 3 Upgrade Offer for Visual Studio Developers

Expression 3 Upgrade Offer for Visual Studio Developers

Like many small development shops and one man/woman software entrepreneurs, I have a limited budget for development tools.  Currently the best value option for me is the  Visual Studio Professional with MSDN Professional subscription. However, this does not give me access to any of the expression products, which would be very useful for Silverlight and WPF projects.

I am particularly interested in using Expression Blend for design work; Sketchflow for customer demo’s and specs; and Expression Encoder for encoding videos for my Silverlight web pages.

The great news is that you can take advantage of the Expression 3 Upgrade Offer if you own a licensed copy of Visual Studio 2005 or later.  The upgrade price offers developers a considerable saving on the full price alternative.

Where are the guides to Security Best Practices in Silverlight?

Silverlight

Silverlight

When I first started writing web application for .NET, I found a great article on security which told me how to create forms authentication and protect myself from sql injection attacks by using stored procedures and parameters.

Today, with Silverlight, we have some additional challenges.  The Silverlight code is now on the clients machine.  How do we protect access to webforms, passwords, or protect our database control string and stop users from reading or stealing our client code?

Most examples out there today are designed as sales pitches, everything is so easy when error handling and security is completely ignored.

I would love to write an article for you that gave you step by step best practices, but like many of you I am still at the start of this exciting journey, so this is a plea to those who are designing these technologies and evangelising their use. 

WE NEED STEP BY STEP EXAMPLES SHOWING SECURITY BEST PRACTICES FOR SILVERLIGHT.

We need examples that can be used by small development teams (1 to 5 people) who are being told by their management (who have just watched or been to one of the flashy launch events) do me a website like MGM Stargate or NBC sports or Continental Airlines, that will handle customer orders in a way that will blow Amazon away.

Resources which I had in 2002 when I started with .Net were:

Defend Your Code with Top Ten Security Tips Every Developer Must Know by Michael Howard and Keith Brown

http://msdn.microsoft.com/en-us/library/aa302370.aspx by Timothy Bollefer, Girish Chander, Jesper Johansson, Mike Kass, and Erik Olsen.

 

A more recent whitepaper for silverlight 2 security is available here

http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=7cef15a8-8ae6-48eb-9621-ee35c2547773

but it is by no means a step by step guide of all of the thing you need to do to make your applications secure.

So come on Scott Hansleman, Tim Heuer, Phil Haack, Scott Guthrie, Beth Massie, The Silvelight Developer Team, The Visual Basic Developer Team, you have been challenged to provide step by step articles and videos or point us to appropriate references.  The articles should be based around Silverlight 3 and technologies which are current today. And, of course, be available in both VB and C#.