Hannes Preishuber

ADO.NET Dataservice This collection already contains an address with scheme http PartII

2009-01-22T20:04:39Z

You may have searched for

This collection already contains an address with scheme http. There can be at most one address per scheme in this collection.

Parameter name: item

I have written some time ago a blog post which have a workaround with removing http headers in iis.

Now I found in documentation prefixfilters which allow the use of ado.net dataservice with multiple host headers on website. There must be some setting in web.config like

  <system.serviceModel>
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" >
    <baseAddressPrefixFilters>
      <add prefix="http://www.vsone.de"/>
    </baseAddressPrefixFilters>
    </serviceHostingEnvironment>
  </system.serviceModel>
</configuration>

No I run in second problem.

IIS specified authentication schemes 'Basic, Anonymous', but the binding only supports specification of exactly one authentication scheme.

OK- it’s easy to change that in IIS. But what's about authenticated access e.g. for Frontpage server extensions?

Still looking….

Next I got a error message

Request Error
The server encountered an error processing the request. See server logs for more details
aha-mhh- which logs- where, WTF?

I found a sloution to display the full error within browser. You have to add in service metadata.

<System.ServiceModel.ServiceBehavior(IncludeExceptionDetailInFaults := true)> _
Public Class EventDataService1

Now I have the next error:

bei System.Data.Metadata.Edm.MetadataArtifactLoaderCompositeResource.LoadResources(String assemblyName, String resourceName, ICollection`1 uriRegistry, MetadataArtifactAssemblyResolver resolver) bei System.Data.Metadata.Edm.MetadataArtifactLoaderCompositeResource.CreateResourceLoader(String path, ExtensionCheck extensionCheck, String validExtension, ICollection`1 uriRegistry, MetadataArtifactAssemblyResolver resolver) bei System.Data.Metadata.Edm.MetadataArtifactLoader.Create(String path, ExtensionCheck extensionCheck, String validExtension, ICollection`1 uriRegistry, MetadataArtifactAssemblyResolver resolver) bei System.Data.EntityClient.EntityConnection.SplitPaths(String paths) bei System.Data.EntityClient.EntityConnection.GetMetadataWorkspace(Boolean initializeAllCollections) bei System.Data.Objects.ObjectContext.RetrieveMetadataWorkspaceFromConnection() bei System.Data.Objects.ObjectContext..ctor(EntityConnection connection, Boolean isConnectionConstructor) bei System.Data.Objects.ObjectContext..ctor(String connectionString, String defaultContainerName) bei eventsEntities..ctor() in C:\Inetpub\vs2005\App_Code\Model1.Designer.vb:Zeile 27. bei invoke_constructor() bei System.Data.Services.DataService`1.CreateDataSource() bei System.Data.Services.DataService`1.EnsureProviderAndConfigForRequest() bei System.Data.Services.DataService`1.ProcessRequestForMessage(Stream messageBody) bei SyncInvokeProcessRequestForMessage(Object , Object[] , Object[] ) bei System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs) bei System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc) bei System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc) bei System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage4(MessageRpc& rpc) bei System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage3(MessageRpc& rpc) bei System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage2(MessageRpc& rpc) bei System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage1(MessageRpc& rpc) bei System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)

Reason now is that I developed with a Silverlight 2 project. And destination is a website. Connection String must be diffrent.

Web Project

connectionString="metadata=res://*/Model1.csdl|res://*/Model1.ssdl|res://*/Model1.msl;

Web Site

connectionString="metadata=res://*;

Silverlight 2.0 Compression Rate

2009-01-02T14:11:00Z

After a short discussion in silverlight forums with a guy who have only 19kb line, I checked out compression for XAP files. A XAP is a zipped package of DLL’s and resources. With winrar installed you can open by context menu from Visual Studio Explorer the xap (clientbin). It contains files like

The size of the package in this case is 750 KB. I unzipped the content and compressed it with Winrar again and- surprise- surprise, package size is now 547 KB. A reduction more than 35%. Only rename the zip back to xap.

I will investigate a little bit, how to automate that within the build process.

B# and Silverlight Isolated Storage

2008-11-29T09:02:54Z

I am a VB developer. As most of expert coder are using C# I must step forward. B# is the language which can be written by VB guys and make it readable for C# gurus. Today's topic is the data store of Silverlight on client side- isolated storage.

Isolated Storage is a concept from .NET. It allows to store information on a per application base, like cookies. Major differences are much more space and more security. There exists several ways to store data. First option is like ASP.NET appsettings.

 Private appSettings As IsolatedStorageSettings = _
           IsolatedStorageSettings.ApplicationSettings ';

Based on a Key Object collection you can store simple data like strings or also complex data like generic lists.

 Dim liste As New List(Of tasks)';
.....
 appSettings.Add("daten", liste) ';
 appSettings.Add("test", New Date)';
 appSettings.Add("hannesKey", "Hannes Preishuber")';

Reading is as simple

 ausgabe.Text = appSettings("hannesKey")';

Isolated storage can also be used like a file system to store images or xaml. Code is written with B#.

Using mystore As IsolatedStorageFile = _
        IsolatedStorageFile.GetUserStoreForApplication()';

There are a lot of samples in web which shows file read and write access. I will top that with storing objects as file. For that object must be serialized. Silverlight supports XAML with DataContractSerializer class or JSON with DataContractJsonSerializer. For the last one you need to reference System.ServiceModel.Web.dll. With following code you can write the generic list as stream.

 Dim memStream As New MemoryStream';
 Dim ser As New DataContractJsonSerializer(liste.GetType)';
 ser.WriteObject(memStream, liste)';
 memStream.Position = 0';
 Dim mystore As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForApplication()';
 Using reader As New StreamReader(memStream)';
    Using writeStream As New IsolatedStorageFileStream("meinObjekt.txt", _
FileMode.Create, mystore)';
           Using writer As New StreamWriter(writeStream)';
                  Dim temp As String = reader.ReadToEnd';
                  writer.Write(temp)';
            End Using';
     End Using';
End Using';

What have been written can be read

Using mystore As IsolatedStorageFile = _';
        IsolatedStorageFile.GetUserStoreForApplication()';
        Using fStream As New IsolatedStorageFileStream( _';
              "meinObjekt.txt", FileMode.OpenOrCreate, mystore)';
            Using sr As New StreamReader(fStream)';
                    ausgabe.Text = sr.ReadToEnd()';
            End Using';
        End Using';
End Using';

The sample writes to Textblock as JSON

same as XML with DataContractSerializer

Input Validation with Silverlight

2008-11-23T10:23:00Z

I miss ASP.NET. With the 2.0 Microsoft had the world best technology for creating applications of all kind. Small or large, ASP.NET 2.0 have features for all. Now several years later we have Silverlight 2 (no 2.0) and should be good as ASP.NET 2.0!? I don't think so- Silverlight have some great advantages but even more missing features. And some of them essential and important.

For me user input validation is one of them. To get the right data from user in correct format is a huge challenge and costs a lot of development time. ASP.NET have rich and easy validator controls to do the job. Silverlight have not.

But Input validation must done, so how? I will show you my approach. First of all, where to validate?

Database
Data Layer
UI Layer
User Interface
Nowhere

I don't like typing things several times. I hate to make data access and type field name 10 times in table, properties and UI. I like the drag and drop stuff and get declaration of where and how my data comes. (no dataset at all ;-)). Silverlight doesn't have that by design and by architecture. The design part comes from Microsoft they have not enough resources to implement every feature within some weeks.

Second problem with data validation comes from loosely connected systems. The user interface is fare fare away from database. Sometimes thousands of km/ miles are between them. Proxy server, hubs, switches even different protocols and ports. So from that view it doesn't make sense to get data schema each time from table and reuse it in UI.

Input validation rules must be declared physical narrow to user interface. The closest thing I can imaging is within the same memory address space.

The practice

Cause of disliking typing code I use a ADO.NET Entity model and a ADO.NET Dataservice to get the data. Visual Studio 2008 creates a proxy class (reference.vb) for the Silverlight project. Database is northwind with table customer. The goal is a input dialog. Phone number is limited to 20 characters. Error is shown as tooltip (zu lange). Textfield is marked as read. Tabbing out will do the validation.

First of all I create the rule set. I do that in the created proxy class (reference.vb) and check the length and throw an exception.

Public Property Phone() As String
        Get
                Return Me._Phone
        End Get
        Set
                If Len(value) > 20 Then
                    Throw New Exception("zu lange")
                End If
                Me.OnPhoneChanging(value)
                Me._Phone = value
                Me.OnPhoneChanged()
        End Set
End Property

Not the best solution. If somebody is updating service reference, your code will be overwritten.

The databinding in the Textbox must have twoway binding and two additional attributes set. That is necessary to get a special event in error case (exception) which will defined in next step

<TextBox Margin="8,8,144,8" Grid.Column="1" Grid.Row="3" 
Text="{Binding Phone,Mode=TwoWay,NotifyOnValidationError=true,  
ValidatesOnExceptions=true}"/>

Then we can create the code for the event BindingValidationError of the grid, named Layoutroot. I decided to show the exception message as tooltip and to change backcolor of Texbox. eventargs gives reference to Textbox and also to eventaction (Added, Removed)

Private Sub LayoutRoot_BindingValidationError(ByVal sender As System.Object, 
ByVal e As System.Windows.Controls.ValidationErrorEventArgs)
     If e.Action = ValidationErrorEventAction.Added Then
            CType(e.OriginalSource, TextBox).Background = _
New SolidColorBrush(Colors.Red)
            ToolTipService.SetToolTip(CType(e.OriginalSource, TextBox), _
e.Error.Exception.Message)
     Else
            CType(e.OriginalSource, TextBox).Background = _
New SolidColorBrush(Colors.White)
     End If
End Sub

Full code for completion

Partial Public Class page29
    Inherits UserControl
    Dim cust As ServiceReference1.NorthwindEntities = _
New ServiceReference1.NorthwindEntities(New Uri("WebDataService1.svc", UriKind.Relative))

    Public Sub New 
        InitializeComponent()
    End Sub

    

    Private Sub page29_Loaded(ByVal sender As Object, 
ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded
        cust.BeginExecute(Of ServiceReference1.Customers)_
(New Uri("Customers", UriKind.Relative), AddressOf fertig, cust)

    End Sub
    Public Sub fertig(ByVal result As IAsyncResult)
        LayoutRoot.DataContext = _
cust.EndExecute(Of ServiceReference1.Customers)(result).First

    End Sub

    Private Sub LayoutRoot_BindingValidationError(ByVal sender As System.Object, 
ByVal e As System.Windows.Controls.ValidationErrorEventArgs)
        If e.Action = ValidationErrorEventAction.Added Then
            CType(e.OriginalSource, TextBox).Background = _
New SolidColorBrush(Colors.Red)
            ToolTipService.SetToolTip(CType(e.OriginalSource, TextBox), 
e.Error.Exception.Message)
        Else
            CType(e.OriginalSource, TextBox).Background = _
New SolidColorBrush(Colors.White)
        End If
    End Sub

    Private Sub Button_Click(ByVal sender As System.Object, 
ByVal e As System.Windows.RoutedEventArgs)
        Dim o As ServiceReference1.Customers = LayoutRoot.DataContext
        cust.UpdateObject(o)
        cust.BeginSaveChanges(AddressOf saveFertig, o)

    End Sub
    Public Sub saveFertig(ByVal result As IAsyncResult)
        cust.EndSaveChanges(result)

    End Sub
End Class

Rownumber in Silverlight Datagrid or Listbox

2008-11-18T19:42:20Z

My next sample uses a converter to show a line number within a datalist. I am not really satisfied with the solution, perhaps I will find in future a better way. But the concept is quite interesting and it works.

First we need a TextBlock to display the row number. The content is controlled by databinding. Unique data (here [daten]) is needed as parameter for later converting.

<ListBox x:Name="lstFields" SelectionChanged="lstFields_SelectionChanged"   
Height="60" VerticalAlignment="Top">
      <ListBox.ItemTemplate>
            <DataTemplate>
            <StackPanel Orientation="Horizontal" x:Name="stack1">
           <TextBlock Text="{Binding daten, 
Converter={StaticResource rownumberconverter} }"></TextBlock>

The converter needs to be declared as resource.

xmlns:c="clr-namespace:SilverlightApplication1test">
    <UserControl.Resources>
        <c:rowNumberConverter x:Key="rownumberconverter"></c:rowNumberConverter>
    </UserControl.Resources>

The converter is implemented as class which uses a special interface. The trick is to get a reference to the original data. As you can see I get a reference to application.current and cast it to the class, which is named page17. Page17 is the xaml page. There I can find my listbox named lstfields and get all items. The items are from type listboxdaten and have a property [daten]. If you compare the property with the value from the converter you get the index of the datarow.

Public Class rowNumberConverter
    Implements IValueConverter
    Public Function Convert(ByVal value As Object, ByVal targetType As System.Type,
 ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object 
Implements System.Windows.Data.IValueConverter.Convert
        Dim mypage As page17 = CType(CType(Application.Current, App).RootVisual, page17)
        For i = 0 To mypage.lstFields.Items.Count - 1
            If CType(mypage.lstFields.Items(i), Listboxdaten).daten = value Then
                Return i + 1
            End If
        Next
        Return "nan" 'should never happen
    End Function

    Public Function ConvertBack(ByVal value As Object, ByVal targetType As System.Type, 
ByVal parameter As Object, ByVal culture As System.Globalization.CultureInfo) As Object 
Implements System.Windows.Data.IValueConverter.ConvertBack
        Throw New NotImplementedException()
    End Function
End Class

get ID inside a Silverlight Datagrid when Button clicked

2008-11-15T10:22:07Z

This blog pots describes a datagrid and a encapsulated custom button for each row. I want to show two methods how to get information about the underlaying data of the row.

I use a ado.net data service and a entity datamodel, which is not part of the article, to get the data. Database is good old northwind and table is customer. When use clicks on button messagebox comes up with some information about the row.

First the xaml code

<Grid x:Name="LayoutRoot" Background="White">
<data:DataGrid x:Name="DataGrid1" >
            <data:DataGrid.Columns>
                <data:DataGridTemplateColumn Width="100">
                    <data:DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <Button Content="{Binding CustomerID}" Click="Button_Click" Tag="{Binding CustomerID}"></Button>
                        </DataTemplate>
                    </data:DataGridTemplateColumn.CellTemplate>
                </data:DataGridTemplateColumn>
            </data:DataGrid.Columns>
</data:DataGrid>

The databinding to the tag attribute is necessary for my first trick

Private Sub Button_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
        MessageBox.Show(CType(e.OriginalSource, Button).Tag)
End Sub

Easy or? Do you like it more complex, than following code gives you the select row as number

Private Sub Button_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
        Dim datenliste As List(Of ServiceReference1.Customers)
        datenliste = DataGrid1.ItemsSource 'automatischer cast
        Dim datenButton As Object = CType(e.OriginalSource, Button).DataContext()
        MessageBox.Show(datenliste.IndexOf(datenButton))
End Sub

Silverlight Multiselect Listbox

2008-11-07T14:44:33Z

The Listbox control of Silverlight 2 have no multi selection. Datagrid have! I want to show how to build a Listbox with Checkboxes and iterate at the end through all items an see if they are checked. Seams to be easy!?

But isn't. You can not access the content of the datatemplate. One solution is to use visualtreehelper to iterate through all controls of controltree. That is quite complkicated cause e.g a checkbox is a composition of Textblock and Rectangle.

I show the databinding way which is quite cool

First I have to generate a class where all data is in and a additional field for the checked value.

Imports System.ComponentModel
Imports System.Collections.ObjectModel
Public Class Listboxdaten
    Implements INotifyPropertyChanged
    Private _checked As Boolean
    Public Property checked() As Boolean
        Get
            Return _checked
        End Get
        Set(ByVal value As Boolean)
            _checked = value
            OnPropertyChanged("checked")
        End Set
    End Property

    Private _daten As String
    Public Property daten() As String
        Get
            Return _daten
        End Get
        Set(ByVal value As String)
            _daten = value
            OnPropertyChanged("daten")
        End Set
    End Property
Public Event PropertyChanged(ByVal sender As Object, ByVal e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged
    Protected Sub OnPropertyChanged(ByVal name As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(name))
    End Sub
End Class

I dont like the typing, but that is another story. Now comes the cool part in XAML. The trick is to do a two way binding.

<ListBox x:Name="lstFields" SelectionChanged="lstFields_SelectionChanged" >
     <ListBox.ItemTemplate>
                <DataTemplate>
              <StackPanel Orientation="Horizontal" x:Name="stack1">
                   <CheckBox x:Name="chkFields" IsChecked="{Binding checked, Mode=TwoWay}"></CheckBox>
                      <TextBlock Text="{Binding daten}"></TextBlock>
                </StackPanel>
         </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>
<Button x:Name="Button1" Width="30" Height="20" Click="Button1_Click"></Button>

A little bit code to fill the data onload

Private Sub page17_Loaded(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded
        lstFields.Items.Add(New Listboxdaten With {.checked = True, .daten = "eins"})
        lstFields.Items.Add(New Listboxdaten With {.checked = True, .daten = "zwei"})
        lstFields.Items.Add(New Listboxdaten With {.checked = True, .daten = "drei"})

A little bit more code to get the items an see if it is checked

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)
        For Each i In lstFields.Items
            If CType(i, Listboxdaten).checked Then
                MessageBox.Show("checked")
            End If
        Next
End Sub

Do you like it? Feel free to comment

Silverlight and ADO.NET Dataservices RTW changes

2008-10-14T21:13:38Z

Till the days of Silverlight RC0 (so yesterday ;-)) we had to generate the proxy class for ado.net dataservice service by hand like:

dataSvcUtil.exe /out:dsProxy.vb /language:VB /uri:http://localhost:64184/eventsDataService1.svc/

Surprisingly the final RTW of silverlight tools for visual studio have the feature to create the proxy by wizard. Everything you have to do, is to select from menu “add service reference” and to press discover button

You get in your project a little bit more then before. The logic is in reference.vb and looks exactly the same as with command line tool.

A instance of the entity is then created with code like that

 Dim srv As New ServiceReference1.eventsEntities

The edmx from the silverlight project is in my case not editable with designer. In the source model, which exists in the website, it works fine.

ADO.NET Dataservices: Fancy Error Part II

2008-10-13T09:13:55Z

Today my first Silverlight 2 application goes live. It is a customer feedback app for the ADC 08 conference. After successfully installed and tested a few hours everything went well. But then data was not show. on direct call of ado.net dataservice vcs in browser following error comes up

Die Datei oder Assembly App_Web_znszzsfo, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null oder eine Abhängigkeit davon wurde nicht gefunden. Das System kann die angegebene Datei nicht finden

The rest of the asp.net site works well.

As I was used to from earlier experience with ADO.NET dataservices on IIS 6 the error message is not what it seams. I tryed restart of IIS, delete temp ASP.NET compiled files of website. Nothing helped.

The original reason was a change of the server ip address by admin. Workaround was to delete temp files from root folder.

ADO.NET Dataservices:This collection already contains an address with scheme http

2008-10-10T17:52:44Z

I have deployed a Silverlight 2 application which uses ADO.NET Dataservices to a IIS 6.

Problem #1: you see nothing in Browser

Problem #2: no data is sown in Silverlight

In my case it was a 2nd hostheader entry in the Web site. Remove the 2nd hostheader, restart the service and call the ADO.NET Dataservice (svc) directly in Browser

I Love VB: Silverlight UI Creation with XML Literals

2008-09-05T06:25:17Z

My actual problem is to develop a image (object) carousel. There are a lot of details to take care about. One of them is to create images dynamically with a great UI like border or shadow. First I startet up to write code like:

 Dim brd As New Border
 brd.Height = 130 'Bildhöhe+ 30 für text
 brd.Background = New SolidColorBrush(Colors.LightGray)
 brd.CornerRadius = New CornerRadius(3)
 brd.BorderThickness = New Thickness(3)
 Dim grdcoll As New GradientStopCollection()
 Dim grdstop As New GradientStop
 grdstop.Offset = 0
 grdstop.Color = Colors.LightGray
  grdcoll.Add(grdstop)

To create a good UI by code is really a pain. It is much easier to draw with Expression Blend. VB 2008 have a feature called XML literals and XAML is XML. So I copy the xaml code direct to Visual Studio like

   Dim ui = <Border xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                         Height="130" CornerRadius="3,3,3,3"
                         BorderThickness="0,0,0,3">
                         <Border.BorderBrush>
                             <RadialGradientBrush>
                                 <RadialGradientBrush.RelativeTransform>
                                     <TransformGroup>
                                         <ScaleTransform CenterX="0.5" CenterY="0.5" ScaleY="0.129"/>
                                         <SkewTransform CenterX="0.5" CenterY="0.5"/>
                                         <RotateTransform CenterX="0.5" CenterY="0.5"/>
                                         <TranslateTransform X="0" Y="0.476"/>
                                     </TransformGroup>
                                 </RadialGradientBrush.RelativeTransform>
                                 <GradientStop Color="#FF706F6F"/>
                                 <GradientStop Color="#FFF7F2F2" Offset="1"/>
                             </RadialGradientBrush>
                         </Border.BorderBrush>
                         <Canvas>
                             <Image Source=<%= "/images/" + dateien(i) %>
                                 Width="100" Height="100"
                                 VerticalAlignment="Top"/>
                             <TextBlock Canvas.Left="0" TextAlignment="Center"
                                 Canvas.Top="100" VerticalAlignment="Center"
                                 Width="100"
                                 >
                                 <%= Replace(dateien(i), ".jpg", "") %>
                             </TextBlock>
                         </Canvas>
                     </Border>

            Dim xaml1 = XamlReader.Load(ui.ToString)
            Me.Children.Add(CType(xaml1, UIElement))

As you can see there is also the posibility to set attributes with expressions (like in asp.net) which I have used for image path. Then you can create from xaml fragment a control and add it to a node of the xaml hierarchy.

Great – I love that way.

The actual result shows the speakers of the ADC conference

Silverlight 2.0 plugin ID or not ID

2008-08-24T06:05:26Z

My original problem was a call from HTMl via Jscript to the internals of a Silverlight plugin. My code fails I had huge problems to find the issue cause debugging doesn’t help and jScript doesnt support intellisense i a complete matter.

My checklist

1) Silverlight 1.0 uses a findname construct, Silverlight 2.0 the xaml class must expose a <Scriptable> member and it must be registered with RegisterScriptObject

HtmlPage.RegisterScriptableObject(

"hannespre", Me)

2) The Call by Jscript from a Silverlight event method like loaded, have a sender object as parameter. On that you can use getHost to get a instance of Silverlight host.

If you call without, like a hmtl button click, you have to find the the Silverlight plugin.

var slhost = document.getElementById("sl1");

3) ASPX or HTML. Silverlight projects in Visual Studio 2008 creates a additional web project. This have to test pages. A html and a aspx.

ASPX

<asp:Silverlight ID="SilverlightControl"

PluginBackground=Transparent

runat="server" HtmlAccess=Enabled

Source="~/ClientBin/SilverlightApplication1test.xap"

MinimumVersion="2.0.30812" Width="100%" Height="600"

HTML

object data="data:application/x-silverlight," id="sl1"

type="application/x-silverlight-2" width="600px" height="400px">

</a>

</object>

The ID of the Silverlight Plugin is set with the ID attribute. There are different default values in ASPX and HTML (XAML1). If you miss the ID, Silverlight will work.

4) you can read the created plugin id during runtime

 Private Sub page8_Loaded(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded
        HtmlPage.RegisterScriptableObject("hannespre", Me)
        label1.Text = HtmlPage.Plugin.Id
End Sub

5) From HTML following code access Plugin

function Button1_onclick()

{

var slhost = document.getElementById("sl1");

slhost.content.hannespre.interntext(

"geht");

}

6) take care on pressing F5 and starting debugging. Can start HTMl or ASPX page (and your code is in other page)

Bind with Expression Blend: cannot create Instance Exception

2008-08-11T05:40:29Z

Databinding with XAML is a lot of work. There is no drag drop table wizard, don’t search for it. Expression Blend (2.5) have a little bit more automatic support for binding Objects. When Blend is in Design View there is under Project tab a Data tab.

Step1: open + CLR Object option- then you get a error message “loading assembly” which can be ignored (what else?)

In the next dialog the class have to be selected which returns the data.

In my case I got 100 times an error in Blend. The exception says nothing for me.

Step 2: Debugging

Expression Blend tries to create a instance of my object during design time. That's a risk cause many parameters can differ to run time like, connections string, database, path and so one.

First there must be some split between design and runtime code. There is a trick to do that. If no htmlpage is present, the container must be something else. Till now a usual container of silverlight xap applications is a browser (and nothing else)

Public Sub New()

' für Blend Designmode

If HtmlPage.IsEnabled = False Then

'dummydaten mit vollem pfad

Dim myxml = XDocument.Load("northwind.xml")

In this container is Blend. Then attach the Blend process to visual studio debugger. For that visual stuido must be open and the project must be compiled. Take Blend for compiling makes it a little bit easier for me. Dont forget to set breakpoint into your constructor.

In my case the code failes on the load place. The reason is ( now I know it) that i have added the XML file as content to my xap packet. But there is no xap package for blend.

The solution is to include the xml as resource into the assembly and load the xml with following code

Dim myxml = XDocument.Load("/databindingvb;component/northwindblend.xml")

Hope this will save you some hour.

set as start page: Silverlight XAML

2008-07-31T08:54:17Z

I really miss the option “set as start page” in Visual Studio Explorer for Silverlight Projects. If I have time in the next days (;-))Ii will write visual studio extension for that purpose.

In fact it is not complicated. The app.xaml have a codebehind file ( app.xaml.vb or app.xaml.cs) which create a instance of the visible XAML. Btw that is the reason for changing xaml to usercontrol in B2.

All you have to to, to change the start page is to change one line of code in startup. Instead of page write the name of the class you want to show.

Private Sub Application_Startup(ByVal o As Object, ByVal e As StartupEventArgs) Handles Me.Startup
        Me.RootVisual = New secondXAML()
End Sub

fast and furios Silverlight Databinding with Gridview and embedded XML Data Resources

2008-07-29T18:32:00Z

I am currently writing a Silverlight 2.0 course. I always try to focus on the problem and reduce the code overhead. For my Module “Databinding with Silverlight 2.0” I try to include the data as raw xml. For that purpose I include a northwind.xml file as data source into the project to focus on datagrid details. The most important part is, to set the build action to content, which ends up in including the xml file into the xap package.

Then you can load the xml directly by xdocument.load. I had problems when xml is not valif or have exoctic encoding ( windows-1252). Rest is a little bit LINQ to create collection of northwinddata objects.

 Dim myxml = XDocument.Load("northwind.xml")

 Dim xmlquery1 = From x In myxml.Descendants("row") _

               Select New northwinddata With _

               {.customerid = x.@CustomerID, _

                .companyname = x.@CompanyName}

 dataGrid1.ItemsSource = xmlquery1

Finally the result

Interesting note at the bottom line. It is also possible to load the xaml content.

 Dim myxml  XDocument.Load("/gird1;component/page.xaml")