Here is the presentation and demo that I created for that event.

Presentation Download ~

• What’s new in Silverlight 4.pptx (2.05 MB)
• What’s new in Silverlight 4 (Office 2003 Format).ppt (2.20 MB)
• Event Photos

Demo Downloads : demo.zip

1. Drag and Drop and Print

I created very simple page that shows the drag and drop feature. And I also included the Jeff Prosise’s SILVERLIGHT 4′S NEW DRAG-AND-DROP SUPPORT demo.

2. Rich Text Area : John Papa

3.WebCam – Photobooth : Karen Corby

4. Validation

5. MultiTouchPuzzle : Scott Guthrie

6. NotificationAPI_CS : Tim Heuer

7. Full Trust – COM

Notes

1. Important to note is that VS RC will not support Silverlight 4 Beta so if you are working on Silverlight 4 development then you should keep VS 2010 Beta only.

2. I’m not able to install it in my office machine. The installation dialog will be disappeared without any message or error after clicking “Install” button. I got this message “[02/09/10,15:45:44] vs70uimgr: [2] UI Thread exiting with error code: -2147172341.” in dd_error_vs_vstscore_100.txt log file. I don’t have any solution for that now. I will update you guys once I found something on this issue.

Blaine Wastell, Program Manager of Microsoft Patterns & Practices Client Program, is asking the community to give the feedbacks for Prism 4.0.  You can go to this link and suggest what you wanna see in v4.0..

One interesting thing is that there are quite a few people who like to use both MEF and Prism in their projects. That’s good thing.. I’m also looking for a MEF + Prism guideline.. Glenn, Hope you heard me. :) I’m still waiting for MEF port of Prism Quick Start as well. :)

Download : Moonlight 3.0 Alpha

But be careful after installing this plugin. You should only use this plugin on trusted sites (e.g. internal or well-known web sites) on non-production computers.

You can read more information in this post http://tirania.org/blog/archive/2010/Feb-03.html

There is very active discussion about MVVM in WPF Disciples User Group. If you are interested then please read all posts and get invoked in discussion. Here is the link. Update: Here is another one.

As I had a MVVM session at my office, I was re-reading a few articles about MVVM. We have very interesting discussion about MVVM in WPF Disciples User Group as well. You can read that post from here.

Someone in Silverlight Forum (link) posted that ~

“There are currently three main areas of criticism regarding the MVVM pattern. The first is that MVVM currently lacks standardization from Microsoft both in implementation and in toolsets. For example, the community has some lack of clarity about where and whether to implement View logic in the View layer or the ViewModel. Given that the MVVM pattern is still relatively new, and that new tool-sets, walkthroughs, or patterns, such as Onyx, Prism, the Microsoft WPF Toolkit, Crack.net, Caliburn and MVVM Light Toolkit are being released, this problem may be solved over time. Microsoft has announced in discussion boards that the MVVM template pattern will be released in Visual Studio 2010.

The second comes from MVVM creator John Gossman himself, who points out that the overhead in implementing MVVM is “overkill” for simple UI operations. He also states that for larger applications, generalizing the View layer becomes more difficult. Moreover, he illustrates that data binding, if not managed well, can result in a considerable excess of metadata in an application. Given these limitations, MVVM may have a practical minimum and maximum size for the type of application it can support, suggesting it may not perform well with large enterprise applications.

The third is that the exercise in creating large numbers of data bindings to the ViewModel results in duplicate code and maintenance problems. Additionally, because of the nature of the semantics of data bindings, critics suggest that the ViewModel does not directly describe the View.”

So, I was thinking it would be great if John and our WPF/Silverlight community can define some simple and obvious rules for MVVM pattern.I understand that there are a lot of way to implement MVVM but at least, there are some obvious rules that everyone can follow so everyone has same understanding about that pattern.

Here are some of my thoughts about MVVM.

Why MVVM?

• Testabiltiy ( ViewModel is easier to unit test than code-behind or event driven code)
• Clear seperation between UX designer and developer
• Increases the “Blendability” of your view
• Model never needs to be changed to support changes to the view
• ViewModel rarely needs to be changed to support changes to the view
• No duplicated code to update views

Do and Don’t in View

• shouldn’t contain any logic that you want to test : As Glenn said that MVVM is not code counting exercise, we can write code in code-behind. But you should never write any logic that you want to test. For example: If user select a country then you want to display the list of states or city in your view. This is the business requirement so you should have unit test to test this logic. So, you shouldn’t write it in code-behind.
• can be a control or Data Template
• Keep the view as simple as possible. : We can still use Data Trigger or Value Converter or Visual State or Blend Behivor in XAML with care.
• use attached property if something is not bindable :

Do and Don’t in ViewModel

• Connector between View and Model
• Keep View State, Value Conversion : (You can create the data structure that you want to display in ViewModel instead of using ValueConverter. For example: You need to show the Name instead of First Name and Last name. Your Model can have First Name and Last Name but You can create Name property in ViewModel. )
• No strong or weak (via Interface) reference of View
• Make VM as testable as possible (e.g. no call to Singleton class)
• No Control related Stuff in VM ( Because if you are changing the view then you will have to change VM as well. )

Model

• can be Data Model, DTO, POCO, auto-generated proxy of domain class and UI Model based on how you want to have the separation between Domain Service and Presentation Layer
• No reference to ViewModel

What do you think about that? Feel free to let me know if you have any comment or suggestion..  Thanks.

UPDATE:

This is the open post. I will keep on updating it based on the feedback. I’m trying to discuss about those rules in WPF Disciples User Group. I understand that there are a few people who don’t want to get invoked in this kinda discussion because it can turn into a fight. Anyway, I will try to discuss with people nicely. :) I will get the feedback several groups like SL MVP/Insiders group, Stackoverflow, Codeproject and etc.

Silverlight MVP and Insiders Web Site

URL: http://wsinsiders.com

This site is where you can find all informations about Silverlight MVP and WPF/Silverlight Insiders. You can also read the series of Silverlight tutorials written by Silverlight MVPs and Insiders. Silverlight Tutorials for Beginners is the first series of our tutorials. We are planning to write more tutorials in that site as well. Here is the list of tutorials that we have in our mind.

Please let me know if you like to contribute your tutorials as well.

Let me tell you a bit about the history of this site. I created this website on Jan 20, 2009. By the time when I was creating this site, there was no MVP award for Silverlight so there was no Silverlight MVP at that time. We had only WPF/Silverlight Insiders and we wanted to create one website similiar to ASPInsiders website. I wanted to register SilverlightInsiders.com but that domain was not available so I registered http://wsinsiders.com/ and started collecting all information about Insiders. Collecting Insiders information is kinda hard because I don’t have any latest list of Insiders and there are a few people who don’t have any blog or BIO or photo. Once I have collected the information about MVP and Insiders, I started planning to write the tutorials with a few MVPs. Braulio Diez Botella,  Alexander Golesh,  Emil Stoychev,  Einar Ingebrigtsen and Daron Yöndem.  Jocelyn Mae Villaraza from Microsoft Singapore helped us to review those tutorials. It took me around 1 years to finish this website. Anyway, I’m glad that we finally make it.

Please feel free to let me know if you have any suggestion or comment for that site.

Open Source Software in Silverlight

URL : http://silverlight-source.net/

I created this website based on one of my favorite website called Open Source Software in C#. There are a lot of open source Silverlight projects. The problem is that all projects are not mature or active so I was thinking it would be so useful for Silverlight community if we have a website that have all information about  active, mature and awesome Silverlight open source projects. You can also suggest me the project via this page http://silverlight-source.net/suggest-project/.

Singapore Silverlight User Group

URL : http://sgsug.org/

This is the official website for Singapore Silverlight User Group. Me and Justin Lee are running this group. We are gonna have our first meetup on 10th Feb, 2010. If you are in Singapore, please come to our meetup. It’s just a casual gathering. You can wear anything you want to come there.

Please take a look at the changes in this page. http://msdn.microsoft.com/en-us/library/ee712881.aspx

This post is just an early look of upcoming Silverlight Model-View-ViewModel Toolkit. I know that this is very early state but I’m writing about this here because I would like to get the feedbacks from the community so that I can prioritize the plans based on what the community want. If you are a fan of WPF MVVM Toolkit then you will probably like it.

Download : SilverlightModelViewApplication.zip (15 KB)

Features

The toolkit includes:

• A Visual Studio 2008 Project Template
• Silverlight Command Implementation
• ViewModelBase that implements INotifyPropertyChanged interface

What is Silverlight MVVM Toolkit?

Silverlight MVVM Toolkit is a Visual Studio project template that has some useful pre-written implementations for Silverlight Command and INotifyPropertyChanged interface. The main intention of creating this toolkit is to help developers to develop the MVVM pattern-based Silverlight application quickly.

I’ve been using this template since a few weeks ago and I found it quite useful because whenever I need to create some samples for my blog or the POC projects for my Office, I always need to create a ViewModal class that implements INotifyPropertyChanged interface and need to add the Prism V2 assembly as a reference in my sample for using DelegateCommand. When I look at WPF MVVM toolkit, I really like it because it saves a lot of my times for copying and pasting the old code from my old sample to new sample. After using WPF MVVM toolkit, I was thinking why not create a project template for Silverlight as well. and now, I did it.

The project template is already attached in this post so you can download and test it in your machine. The msi file for that template is not ready yet but I will show you very simple steps (just two steps only) to make it visible in Project Template Dialog of Visual Studio 2008.

How to install Silverlight Model-View-ViewModel Toolkit

Please download the zip file (Don’t extract it) and close all Visual Studio 2008 instances before following the steps below ~

Step #1: Copy and paste SilverlightModelViewApplication.zip under this path below

%ProgramFiles%\Microsoft Visual Studio 9.0\
Common7\IDE\ProjectTemplates\CSharp\Silverlight\1033

Step #2. Open Visual Studio 2008 Command Prompt and type “deven /setup”

Yes. That’s all for installing new project template for Visual Studio.

Once you have finished registering new project template, you open the Visual Studio 2008 and check “New Project” dialog.  Then, you will get new project template “Silverlight Model View Application” under Silverlight project type as shown in picture below.

Choose that template to create a Silverlight MVVM appliction. Note that linking with ASP.NET project, enabling the RIA service and generating unit-test project are not availble in this template but I will add all of this later.

The structure of Silverlight MVVM project is as below.

Commends

Let’s talk about classes under Commands.  The Command implementation that I’m using in this toolkit is from CompositeWPF version 2. I know that I can probably roll my own implementation but I’ve been using Prism for long time and DelegateCommand is working perfectly fine so I dont think that I need to waste my time to do the duplicated things. Please feel free to let me know if you found something that is not supported by DelegateCommand.

Here is the examples for using DelegateCommand.

XAML

xmlns:cmd="clr-namespace:SilverlightModelViewApplication4.Commands"

Here is how you can use Command Binding and CommandParameter in Silverlight.  ( The earlier implementation of Prism v2 is cmd.Command.Click but Prism team re-named this to Click.Command at drop 9.  You can read this post if you like to know why they did the changes)

<Button
cmd:Click.Command="{Binding SearchCommand}"
cmd:Click.CommandParameter="This is a CommandParameter"
/>

</div>
<div id="_mcePaste" style="position: absolute; left: -10000px; top: 2503px; width: 1px; height: 1px; overflow-x: hidden; overflow-y: hidden;"><Button</div>
<div id="_mcePaste" style="position: absolute; left: -10000px; top: 2503px; width: 1px; height: 1px; overflow-x: hidden; overflow-y: hidden;">cmd:Click.Command="{Binding SearchCommand}"</div>
<div id="_mcePaste" style="position: absolute; left: -10000px; top: 2503px; width: 1px; height: 1px; overflow-x: hidden; overflow-y: hidden;">cmd:Click.CommandParameter="This is a CommandParameter"</div>
<div id="_mcePaste" style="position: absolute; left: -10000px; top: 2503px; width: 1px; height: 1px; overflow-x: hidden; overflow-y: hidden;">/></div>
<div id="_mcePaste" style="position: absolute; left: -10000px; top: 2503px; width: 1px; height: 1px; overflow-x: hidden; overflow-y: hidden;">

C#

public DelegateCommand<string> SearchCommand { get; set; }

//Construtor
public MainPageViewModel()
{

SearchCommand = new DelegateCommand<string>((arg) =>
{
MessageBox.Show(arg);
});

}

INotifyPropertyChanged implementation

Some of you might know that I wrote about how to implement INotifyPropertyChanged interface with Expression Tree so you don’t need to use any magic string in property setter.  If you haven’t read it yet, please go and read this post to get some idea. I implemented the same implementation in ViewModelBase class of this toolkit so you can probably use this feature as below in ViewModel class.

//Example: How to use RaisePropertyChanged without having any magic string.

private string name = string.Empty;

public string Name
{
get { return name; }
set {
name = value;
this.RaisePropertyChanged(p => p.Name);
}
}

Upcoming Features ~

• A Project Template Waziard for linking with ASP.NET, enabling RIA Services and generating a Text project that has the references o Silverlight Unit Test Framework and Silverlight Moq
• A C# and VB.NET project template that supports all editions (inlcuding express edition) of Visual Studio 2008
• Creating a msi installer by using Windows Installer XML (WiX) toolset

Questions?

I have a few questions for you guys.

1. What kind of functionalities do you guys like to see in this toolkit? For example: Extensions/Attached properties, Utilities and etc
2. Do you think that I should create an installer (msi) for that? OR is it okay to have zip file and register it by youself with two simple steps? I’m asking you this because in order to create a msi, I will probably need to spend some times for learning Windows Installer XML (WiX) toolset. So, if you guys are okay with two simple steps, I can work on other things first.

Feel free to drop a comment if you have any comment or suggestion for this toolkit. If you already have similar things in your mind, please let me know. We can work together to contribute our community. You can also reach me with this email mchlsync AT gmail DOT com.

I will be hosting this project in codeplex.com once it’s ready.

Problems

UpdateSourceTrigger is not supported in Silverlight until version 3.o.

Workaround

You will need to set the focus on other controls and re-focus to the control that you are using. For example: You are typing in TextBoxA. You want to have UpdateSourceTrigger support for that textbox. So, what you have to do is that you need to change the focus on another control (e.g. TextboxB) and re-set the focus on TextboxA while typing.

Yes. you can do it very easily from code-behind. But ( genius? ) people from pattern world don’t like the idea of using code-behind file (so, creating a code-behind file for each and every xaml in Visual Stuid is a waste? What about changing the default pattern (MVC) to MVVM in Visual Stuido Template? ) Anyway, let me get back to the topic. So, we can probably create an attached property to workaround the UpdateSourceTrigger in Silverlight.

Note: This code is just giving you some idea how you can workaround the issue. You will need to do the modification based on your need.

Let’s name our attached property aS “UpdateSourceTriggerHelper”. We will add some codes for registering the property and getter/setter as below. I will tell you more about OnUpdateSourceTriggerChanged

public class UpdateSourceTriggerHelper
{
public static readonly DependencyProperty UpdateSourceTriggerProperty =
DependencyProperty.RegisterAttached("UpdateSourceTrigger", typeof(bool), typeof(UpdateSourceTriggerHelper),
new PropertyMetadata(OnUpdateSourceTriggerChanged));

public static bool GetUpdateSourceTrigger(DependencyObject d)
{
return (bool)d.GetValue(UpdateSourceTriggerProperty);
}

public static void SetUpdateSourceTrigger(DependencyObject d, bool value)
{
d.SetValue(UpdateSourceTriggerProperty, value);
}

In OnUpdateSourceTriggerChanged method, we are going to add the logic for focusing other controls and re-setting the focus back to the original control. So, we need to walk throught the Visual Tree to get the object of other control. Please take a look at findFocusableControl();

private static void OnUpdateSourceTriggerChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TextBox textBox = d as TextBox;
if ((bool)e.OldValue)
{
textBox.TextChanged -= (s, arg) => {

};
}
if ((bool)e.NewValue)
{
textBox.TextChanged += (s, arg) => {
var c = findFocusableControl(textBox);
if (c != null)
{
c.Focus();
}
textBox.Focus();
};
}
}

Let’s take a look at what we did in findFocusableControl(). Based on the control that you are typing, you can get the parent of control by using VisualTreeHelper. But if you want to use this code in production, you will have to modify the code. (For example: if you can’t find any parent then you will need to find the child element. and you need to check whether that control that you get from Visual Tree Helper is focusable or not. yes. there are a lot of things to do it.)

private static Control findFocusableControl(Control control)
{
var ctl = VisualTreeHelper.GetParent(control);
if ((ctl as Control) != null)
{
return ctl as Control;
}
else
{
int childrenCount = VisualTreeHelper.GetChildrenCount(ctl);
for (int i = 0; i < childrenCount; i++)
{
var c = VisualTreeHelper.GetChild(ctl, i) as Control;
if ((c != null) &amp;amp;amp;amp;amp;amp;amp;&amp;amp;amp;amp;amp;amp;amp; (c != control))
{
return c;
}
}
}
return null;
}
}

Here is how we can use our attached property to provide PropertyChanged event.

Usage (Example)

<UserControl x:Class="UpdateSourceTriggerExtDemo.Page"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:UpdateSourceTriggerExtDemo"
Width="400" Height="300">
<Grid x:Name="LayoutRoot" Background="White">
<StackPanel>
<TextBox x:Name="nameTextbox" Height="25" Width="100" Margin="5" Text="{Binding Name, Mode=TwoWay}"
local:UpdateSourceTriggerHelper.UpdateSourceTrigger="True" />
<TextBox x:Name="addressTextbox" Height="25" Width="100" Margin="5" Text="{Binding Address, Mode=TwoWay}"
local:UpdateSourceTriggerHelper.UpdateSourceTrigger="False" />
<TextBox x:Name="phoneTextbox" Height="25" Width="100" Margin="5" Text="{Binding Phone, Mode=TwoWay}"
/>
<Button Height="25" Width="100" Margin="5" Content="Save" />
</StackPanel>
</Grid>
</UserControl>

Hope it helps. Feel free to let me know if you have any better solution.. I’m always open to any suggestion from you guys. Thanks..

Happy Silverlighting!!!

Here is the steps to reproduce the issue.

Error:

Could not load file or assembly ‘ABCDE.Resources, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null’ or one of its dependencies. The system cannot find the file specified.

I got that error and also, I found that “ABCDE.Resources” assembly is not getting generated in Silverlight. So, I reported this issue in WPF/Silverlight Insider List. What I heard from Microsoft is that this is by-design issue. Silverlight’s application activation logic treats this with special meaning – it recognizes such an assembly as a satellite resource assembly. Then, I tried to reproduce the issue  just like the way that we used in our project without using any code but just resx file.

Here is new steps to reproduce the issue.

1. Create Silverlight Application (e.g. SilverlightApplication4 ) with web project attached.  (both Silverlight 2 or Silverlight 3)
2. Add Silverlight Class Library and named it “ABCDE.Resources”  <Note: This is very important.>
3. Add new resx file (Let’s call it “Strings.resx”)
4. Change “Access Modifier :” to Public
5. Add new string to that resx file “Strings.resx”
   e.g: (Name: YourMessageStringInResx, Value=YourMessageStringValueInResx)
6. Go to Code-behind of that resx file “Strings.Designer.cs” and change private constructor to public. (why? yes. this is another issue. )
7. Go to Page.xaml.cs
8. Add the following line in constructor.

   Console.WriteLine(Strings.YourMessageStringInResx);
   

Then, run the application. I’m sure that you will get the same error. I’m still waiting the response from Microsoft for that issue and I will update this post as soon as I get one. As of now, the only solution for this issue is that don’t name “.Resources” for your class library and use other name like ABCDE.Languages or ABCDE.Rex or etc.

Hope it helps.