Thursday, December 30, 2010

TestComplete now supports Silverlight 4

Today I got chance to work with TestComplete to automate a Silverlight application.

If you need to get the support for Silverlight object recognition you need to patch your xap with a TestComplete utility. The patch just adds 2 dlls into your xap and updates the AppManifest.xaml file.

We have an application which uses same code base for WPF as well as Silverlight .Hope our WPF test scripts will execute for testing Silverlight version as well.

Monday, November 22, 2010

Silverlight training - some questions

After a while I had to conduct training in my company.Earlier it was WPF and now the topic is Silverlight.I dont know whether Silverlight training is relevant now because of HTML 5.According to me next version of ASP.Net may be 5.0 or 6.0 will emit html5 which may reduce the need of Silverlight in the RIA world.But in other context Silverlight is valuable because of Windows 7 mobile development.

Anyway I have started training and conducted one small test in order to evaluate my students.I am not going to share their scores but some questions I have asked.

  • Which code snippet determines whether the Silverlight application is running inside browser or OOB?
    1. App.GetState()
    2. System.Windows.Application.Current.IsRunningOutOfBrowser
    3. System.AppDomain.CurrentDomain.IsRunningOutOfBrowser
    4. Silverlight.IsRunningOutOfBrowser
  • Can we create folder in IsolatedStorage? (Yes/No)
  • Can we redirect the browser to a ASPX/HTML page from Silverlight?(Yes/No)
  • What is possible in OOB without using COM objects?
    1. Access registry
    2. Access file from C: drive
    3. Access file from MyDocuments
    4. All
  • Is it possible to refer a WPF 4.0 dll in Silverlight? (Yes/No)
  • Where we normally specify the window less mode?                           
    1. Hosting HTML page
    2. App.xaml.vb
    3. MainPage.xaml.vb
    4. None of the above                           
  • Where is isolated storage located?
    1. Main memory of server
    2. Hard disk of client
    3. Main memory of client
    4. Database
  • Can <Resources> tag in a xaml page contain a boolean value?(Yes/No)
  • Can we write code behind of ABC.xaml in XYZ.vb? (Yes/No)
  • Can Silverlight application access ASP.Net Session variable?
  • How Silverlight application gets values from its browser host at initialization time?                               
    1. Through constructor of App class                               
    2. Through Environment.CommandLine property                               
    3. Using ProvideInitValues event                               
    4. None of the above
  • How to add a resource programatically?
    1. Me.Resources.Add(1, New SolidColorBrush(Colors.Green))
    2. Me.Resources.AddResource(1, New SolidColorBrush(Colors.Green))
    3. Me.AddResource("mycolor", New SolidColorBrush(Colors.Green))
    4. None of the above
  • What is the base class of UserControl class?                           
    1. Control
    2. UIElement
    3. DependencyObject
    4. UserControlBase      
  • How Silverlight application can access SQL database ?
    • Through SQLDataAdapter
    • Through ODBC connection
    • Using WebService
    • Using Windows service     
  • Last question was to create a simple <Grid> based layout of a login page.

If you are a Silverlight developer you may feel that some questions are silly or too simple.But my students are in different categories.Some had projects in Silverlight others are hearing word Silverlight for the first time.So its a mix and people can just start learning concepts even if they are not able to answer.

Hope I don’t have to provide answers to these questions since all are known.Let me know if anybody needs clarification.

NB: These are not Silverlight interview questions and I think nobody will ask these type of questions in interview.

Tuesday, October 5, 2010

Why it is asking to update Silverlight version

So  many times I have seen this type of messages in dev environment.Now understood what was the reason..I was doing the same without knowing the actual facts.

Monday, September 27, 2010

Getting Silverlight version

Here is the post which gives you how to get the Silverlight version through Javascript.

If you want to get the Silverlight version inside Silverlight code you may invoke this function as follows.

Saturday, September 18, 2010

Silverlight security aspects

The below link explains the security aspects of Silverlight. ie differences among the Transparent code,Safe critical code and Critical code along with the theory of user initiation.

Monday, September 13, 2010

Using dynamic keyword in browser interaction

In my general code blog I talked about usage of dynamic keyword in Silverlight browser interaction applications.Here is the sample with source.

Generally the browser interaction is used to communicate with the browser elements from Silverlight application.Its not at all type safe.So we use the general methods like SetProperty to talk to the com objects.

The 'innerText' property isn't defined at compile-time - it's a Javascript property on the div. The way to do this without the dynamic keyword is:

var myDiv = HtmlPage.Document.GetElementById("myDiv");
myDiv.SetProperty("innerText", "Text was replaced!");

We can replace the SetProperty as the real property usage if we use the dynamic keyword.

dynamic myDiv = HtmlPage.Document.GetElementById("myDiv");
myDiv.innerText = "Text was replaced!";

Download the sample from here

Sunday, August 8, 2010

Single window F1 help in Silverlight

I know the title is confusing.You will know why I gave this title when you read further.When we talk about the Rich Internet Application we could see that they are half desktop and half web.The UI resembles a desktop application but they behave like web applications.

As we know all the desktop applications comes with a help.We all would like to have a help popup on F1 key when we are struck on a desktop’s functionality. The same applies to RIA.Due to its richness like desktop we should have a F1 help window.This post talks about implementing a F1 help window for Silverlight applications.

Basically we need to capture the F1 key and show a popup.I don’t think people expects a huge hlp file on F1 because this is web and downloading a big file will take time.So better we can choose html or based help which are context based and easy to load. Now the things are simple just show a html popup on F1 press.

Here I am adding one good feature of Silverlight.Attached properties. This extends one class by introducing a new property implemented in another class.I am not going into details of attached properties.We can write a HelpProvier class which holds the attached property so that we can set the help source as follows from anywhere in our application.

<UserControl x:Class="F1Help.MainPage"
<Grid x:Name="LayoutRoot" Background="White" local:HelpProvider.Source="help.htm">
<TextBox Text="Enter the datas here"></TextBox>

Lets see how the HelpProvider is processing the F1 key.

using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Windows.Browser;

namespace F1Help
public class HelpProvider
public static Uri GetSource(DependencyObject obj)
return (Uri)obj.GetValue(SourceProperty);
public static void SetSource(DependencyObject obj, Uri value)
obj.SetValue(SourceProperty, value);
public static readonly DependencyProperty SourceProperty =
DependencyProperty.RegisterAttached("Source", typeof(Uri), typeof(HelpProvider), new PropertyMetadata(OnSourcePropertyChanged));
public static void OnSourcePropertyChanged(object sender, DependencyPropertyChangedEventArgs e)
if (e.NewValue != null && e.NewValue is Uri)
FrameworkElement element = sender as FrameworkElement;
element.KeyDown+=new KeyEventHandler(element_KeyDown);
static void element_KeyDown(object sender, KeyEventArgs e)
if (e.Key == Key.F1)
e.Handled = true;
e = null;
if (GetSource(sender as DependencyObject) != null)
ShowHelpFile(GetSource(sender as DependencyObject));
private static void ShowHelpFile(Uri source)
HtmlPage.Window.Navigate(source, "new");

The code is self explanatory.In the property changed method we are subscribing to the keydown event of the UIElement which requested help implementation.The event handler shows the htm file in a popup.Simple…

But you can see yourself this is not as simple as we thought when you run the app.F1 will show our help as well as browser help.The user needs our help only when he is in our application.So we need to avoid browser help at any cost.What to do? I know what everybody thinking as web developers.Yes Javascript…

function HideHelp() {
document.onhelp = function () { return (false); }
window.onhelp = function () { return (false); }

Call this function on document.onload.This is tested only in IE 8.Sample can be downloaded from here.

Monday, May 17, 2010

Location of OOB xap file in local file system

Everybody knows that there is Out of browser support in Silverlight 3 and Silverlight 4.Basically how it is working? Its simple.It downloads the xap file into a local folder and runs the xap from that location as similar to in browser.But with some more privileges.

All that are fine.So to which location the xap files is getting downloaded in my local machine? It’s very easy to find out.Right click on the OOB application icon in desktop and get select properties.You can get the application id.Using that application id you can find the application folder in the Out-of-browser cache in the below location.

C:\Users\<login id>\AppData\Local\Microsoft\Silverlight\OutOfBrowser

Saturday, April 24, 2010

Silverlight 4 RichTextBox lab

Got the below lab when I was looking for the usage of RichTextBox in Silverlight 4.This gives an idea how to use RichTextBox.

More labs here

Wednesday, April 21, 2010

Parser internal error: Object writer 'xClassNotDerivedFromElement'

If you are a Silverlight developer there is a chance that you may get the exception “Parser internal error: Object writer 'xClassNotDerivedFromElement'” very rarely which is difficult to track.Even you can’t put break points to track this.As a developer you will google the same.But most probably you will not get any results.

Only thing went wrong here is the namespace.But this is not at all mentioned in any of the exception The project which you are working on will not have a namespace or somebody in the project might forgot put the namespace in XAML or code files.

So make sure that there is namespace present in the project and the xaml files are correctly mapped to the corresponding code files in the x:Class attribute.

Note : We cannot have Silverlight projects without namespace.

I came to see this exception when one of my colleagues tried to write code which should  compile in both Silverlight 4 and WPF 4.

Saturday, March 20, 2010

Creating WCF proxy without reference

The problem : Creating WCF proxy in Silverlight without using the add service reference and it’s auto generated code

It was a debate that whether we can call a WCF service from Silverlight without using “Add Service Reference” menu item.In WPF or in the other .Net environments it is easy.We just need to refer the contracts dll and write a class which inherits from ClientBase.But this is Silverlight - A different runtime.

A Normal WCF service reference with all the generated code files

There were 3 opinions.Not at all possible,Possible with less amount of code,Possible if we create all those classes by our own.Just avoid the last one because that doesn’t give us any benefit as it is just making the process manual.

One of my Colleagues started research on that and was able to achieve the same.I am just sharing the idea.

Solution : We can achieve the same using contract interface,proxy class and a custom eventargs class

First of all there are no changes at the server side.Only 3 types we are going to write at client side which will be present in the reference.cs file if you create the proxy using “Add Service Reference” Dialog.

There will be a question for sure.Why are we writing the code which is being auto generated ? Why don’t we create a reference using the dialog and copy paste the reference.cs code?

The answer for both the questions is same.You can create reference using the dialog and get the code from reference.cs.That is enough.


  • Can avoid huge amount of code which is auto generated.
  • This is acting as a separate layer and can encapsulate operations here in future.

Implementation steps

Lets take example of implementing a DataService with one method GetData which returns a string.Don’t bother about the server side.Use the same.Below are the steps to perform at client side ie Silverlight side.

  1. Create interface IDataService
    1. Decorate with ServiceContract attribute.
    2. Add method BeginGetData.Decorate it with OpertionContract and Set AsyncPattern to True.
    3. Add Method EndGetData.
      Imports System.ServiceModel

      <ServiceContract()> _
      Public Interface IDataService
      <OperationContract(AsyncPattern:=True)> _
      Function BeginGetData(ByVal callback As System.AsyncCallback, ByVal asyncState As Object) As System.IAsyncResult
      Function EndGetData(ByVal result As System.IAsyncResult) As String
      End Interface

  2. Create eventArgs class deriving from System.ComponentModel.AsyncCompletedEventArgs

    1. Add required properties to pass values.

      Public Class GetDataCompletedEventArgs
      Inherits System.ComponentModel.AsyncCompletedEventArgs

      Private results() As Object

      Public Sub New(ByVal results() As Object, ByVal exception As System.Exception, ByVal cancelled As Boolean, ByVal userState As Object)
      MyBase.New(exception, cancelled, userState)
      Me.results = results
      End Sub

      Public ReadOnly Property Result() As String
      If Me.results IsNot Nothing Then
      Return CType(Me.results(0), String)
      End If
      Return Nothing
      End Get
      End Property
      End Class

  3. Create class DataServiceProxy derived from ClientBase which Implements IDataService.Write constructors.Implement methods.Write delegates and event which communicate back to the caller.

Public Class DataServiceProxy
Inherits ClientBase(Of IDataService)
Implements IDataService
#Region " Constructors"
Public Sub New()
End Sub

Public Sub New(ByVal endpointConfigurationName As String)
End Sub

Public Sub New(ByVal endpointConfigurationName As String, ByVal remoteAddress As String)
MyBase.New(endpointConfigurationName, remoteAddress)
End Sub

Public Sub New(ByVal endpointConfigurationName As String, ByVal remoteAddress As System.ServiceModel.EndpointAddress)
MyBase.New(endpointConfigurationName, remoteAddress)
End Sub

Public Sub New(ByVal binding As System.ServiceModel.Channels.Binding, ByVal remoteAddress As System.ServiceModel.EndpointAddress)
MyBase.New(binding, remoteAddress)
End Sub
#End Region

#Region "GetData"
Private onBeginGetDataDelegate As BeginOperationDelegate
Private onEndGetDataDelegate As EndOperationDelegate
Private onGetDataCompletedDelegate As System.Threading.SendOrPostCallback
Public Event GetDataCompleted As System.EventHandler(Of GetDataCompletedEventArgs)

Public Function BeginGetData(ByVal callback As System.AsyncCallback, ByVal asyncState As Object) As System.IAsyncResult Implements ServiceContracts.IDataService.BeginGetData
Return MyBase.Channel.BeginGetData(callback, asyncState)

End Function

Public Function EndGetData(ByVal result As System.IAsyncResult) As String Implements ServiceContracts.IDataService.EndGetData
Return MyBase.Channel.EndGetData(result)
End Function

Private Function OnBeginGetData(ByVal inValues() As Object, ByVal callback As System.AsyncCallback, ByVal asyncState As Object) As System.IAsyncResult
'Dim engID As String = CType(inValues(0), String)
'Dim libraryID As String = CType(inValues(1), String)
'Dim folderName As String = CType(inValues(2), String)
'Dim parentFolder As PathInfo = CType(inValues(3), PathInfo)
'Dim folderGeneralProperties As FolderGeneralProperties = CType(inValues(4), FolderGeneralProperties)
'Dim additionalProperties As System.Collections.Generic.Dictionary(Of String, String) = CType(inValues(5), System.Collections.Generic.Dictionary(Of String, String))
Return CType(Me, IDataService).BeginGetData(callback, asyncState)
End Function

'Private Function GetData() As String Implements IDataService.GetData
'Return MyBase.Channel.GetData()
'End Function

Private Function OnEndGetData(ByVal result As System.IAsyncResult) As Object()
Dim retVal As String = CType(Me, IDataService).EndGetData(result)
Return New Object() {retVal}
End Function

Private Sub OnGetDataCompleted(ByVal state As Object)
'If Not (GetDataCompleted Is Nothing) Then
Dim e As InvokeAsyncCompletedEventArgs = CType(state, InvokeAsyncCompletedEventArgs)
RaiseEvent GetDataCompleted(Me, New GetDataCompletedEventArgs(e.Results, e.Error, e.Cancelled, e.UserState))
'End If
End Sub

Public Overloads Sub GetDataAsync()
If (Me.onBeginGetDataDelegate Is Nothing) Then
Me.onBeginGetDataDelegate = AddressOf Me.OnBeginGetData
End If
If (Me.onEndGetDataDelegate Is Nothing) Then
Me.onEndGetDataDelegate = AddressOf Me.OnEndGetData
End If
If (Me.onGetDataCompletedDelegate Is Nothing) Then
Me.onGetDataCompletedDelegate = AddressOf Me.OnGetDataCompleted
End If
MyBase.InvokeAsync(Me.onBeginGetDataDelegate, New Object() {}, Me.onEndGetDataDelegate, Me.onGetDataCompletedDelegate, Nothing)
End Sub
#End Region
End Class

Uploaded a sample which does the same.

Wednesday, March 3, 2010

Silverlight Installation issues I faced

Here are some details about the installation issues which I faced when tried to setup my machine for Silverlight 4 with Visual studio 2010. No need to read further, if you are able to setup your machine with Silverlight 3 + VS 2008 and Silverlight 4 + VS 2010 without issues ;-)

After the completion of previous project which is done in VSTS 2008 and Silverlight 3 we decided to port the same to Silverlight 4.According to my knowledge it is difficult to have 2 versions of Visual studio if any version of them are in beta.Here to work with Silverlight 4 we need Visual studio 2010 beta 2.So normally I uninstalled Silverlight 3 and  started uninstalling VS 2008.

Everything went fine until my onsite counterpart called and asked me to setup my machine with VS 2008 + Silverlight 3and VSTS2010 beta 2 + Silverlight 4 beta .The reason was simple.We may need to support client for the previous project.The good news was he setup his machine with the above mentioned configuration.

So I stopped the uninstallation of VSTS 2008.Seems the problems started here.Started installation of Silverlight 3.Got the simple error message.Not able to complete the installation.Log says a previous version of Silverlight is there.Tried with different versions of Silverlight 3 which were available with colleagues.Hours passed with Uninstallations, Installations and reboots.Finally downloaded the Silverlight 3 version from net and tried.That too not worked out.

As usual I asked Google what is this error message by pasting the installation log in search box.Got a good link with Silverlight error messages and their solutions.

Silverlight 3 installation Error messages :

I figured out that there are 2 patches which are stopping me from installation.They are KB967143 and KB956453 and the solution was to manually uninstall those.But when I tried uninstalling it said “Update removal was disallowed by policy”.What policy ? Its My machine and my login with admin privileges.I haven’t set any policy.

After a google I came to know more things about the patches.There are different types of patches and these patches fall into UNINSTALLABLE patch category.The only solution was to reinstall the application without applying those patches.

Uninstallable patches:

Again uninstalling and installing VS 2008.Then Silverlight 3.Next series was VS 2010 beta 2 and Silverlight 4 beta.Tested whether the old project is running or not in VS 2008 and creation of Silverlight 3 and 4 projects in VS 2008 and VS 2010 respectively.Overall cost - a weekend and 2 week days.

Sometimes I am getting error message “VB.Net compiler is not responding” when I compile Silverlight 3 projects in VS 2008.But not consistent.Other than that everything works perfect.

Tuesday, March 2, 2010

Add Reference is empty in Silverlight 4 Beta

As I told in the last post ,I have started with the Silverlight 4 research using Visual Studio 2010 beta 2 .The first thing I noted is the add reference box in Silverlight project is empty.

According to Microsoft this is a bug and has fixed.
In the add reference dialog manually browse the dll from the folder [Install Drive]:\Program Files\Microsoft SDKs\Silverlight\v4.0\Libraries\Client

Saturday, February 27, 2010

Return of the blogger

I was not able to blog more after joining my current company because of an important project.That project was in Silverlight 3 to show an existing big business application can be ported to Silverlight 3 and runs properly.

We achieved our goal this week and the client accepted the same.According to my small experience that project will be the biggest business application ever built using Silverlight or even RIA technologies.Sorry I am not in a position to tell any more details about that application due to NDA.

Anyway we are progressing to port the same to Silverlight 4 and the research for that is already started. Thats it for now.Stay subscribed for more news. 

Friday, January 29, 2010

Silverlight Media Framework v1.1 Released

This open source framework will make developer’s work much easier when they develop a media player for Silverlight.

More details in codeplex along with videos shows how to use it.

PDF Viewer for Silverlight

It seems the days of HTML overlay is coming to an end.A pdf viewer for Silverlight is ready by first floor software who gives Silverlight spy.Read the details here.

See it in action here

Monday, January 25, 2010

What is Managed Entity Framework - MEF

After joining in new company I rarely get time to learn new technologies than my previous company.Obviously its due to more responsibilities.But this week end I was managed to find some time to learn MEF (Managed Entity Framework) which was introduced some time back.

In simple words its all about Export,Import and you export a type or property then you import into another property which is present in another class.For this to happen there should be somebody in the middle.That is composition.

The export and import takes place by using attributes.Just decorate the class or property with the attribute export or import to achieve the functionality.For composition you just need one line code :-)

Exporting one type

public class Employee

The above code just exports one class.Lets see how this is being used or imported.

public class EmployeeViewModel
[Import ("Emp")]
public Employee Current { get; set; }

The employee view model class receives the exported type as Current.This code it not completed.To complete the code we need to compose.It is done by the line below.

public EmployeeViewModel()

This is the constructor of EmployeeViewModel class and the first line does the composition and after that if we access the object it will be initialized and ready for use.In this case it will display the default ToString method’s output ie the class name.

This is the basic concept of MEF.This can be used in data binding and for collection types etc…Next time will discuss about a data binding and MEF.

The project contains a reference to the dll System.ComponentModel.Composition.dll.You can locate this file from the attached sample or in the Silverlight 4 installation.

Sample can be downloaded from here.

Sunday, January 17, 2010

Performance optimization in Silverlight 3

Just now got a good link in MSDN for performance optimization in Silverlight 3 applications.

Don’t know when can I get a chance to apply this in my current project :-(