public async void ProcessPage(Uri url)
{
  Task<string> downloader =  new WebClient().DownloadStringTaskAsync(url);
  string pageData = await downloader;
  // ... process ...
}

       /// <summary>
        /// A collection for ItemViewModel objects.
        /// </summary>
        public ObservableCollection<ItemViewModel> Items { get; private set; }

       /// <summary>
        /// A collection for Category and ItemViewModel objects.
        /// </summary>
        public ObservableCollection<ViewModelBase> CategoriesAndItems { get; private set; }

        /// <summary>
        /// Creates and adds a few ItemViewModel objects into the Items collection.
        /// </summary>
        public void LoadData()
        {
            // Sample data; replace with real data
            this.Items.Add(new ItemViewModel() {
                                  Id=Items.Count,
                                  Group="Group 1",
                                  LineOne = "runtime one",
                                  LineTwo = "Maecenas ... bibendum" });
                // ....
            this.Items.Add(new ItemViewModel() {
                                 Id = Items.Count,
                                 Group = "Group 4",
                                 LineOne = "runtime sixteen",
                                 LineTwo = "Nascetur....t pulvinar" });

            var categories = from i in Items
                                     group i by i.Group into category
                                     select new CategoryViewModel(category.Key, category);
            foreach (var category in categories)
            {
               CategoriesAndItems.Add(category);
                foreach (var item in category.Items)
                {
                    CategoriesAndItems.Add(item);
                }
            }
            this.IsDataLoaded = true;

            NotifyPropertyChanged("ItemsView");
        }

<Application.Resources>
        <DataTemplate x:Key="TestGroupedList.CategoryViewModel">
            <TextBlock Text="{Binding CategoryText}"
                       Style="{StaticResource PhoneTextGroupHeaderStyle}"
                       Margin="0,18,0,0"/>
        </DataTemplate>
        <DataTemplate x:Key="TestGroupedList.ItemViewModel">
            <StackPanel Margin="32,0,0,17"
                        Width="432">
                <TextBlock Text="{Binding LineOne}"
                           TextWrapping="Wrap"
                           Style="{StaticResource PhoneTextExtraLargeStyle}" />
                <TextBlock Text="{Binding LineTwo}"
                           TextWrapping="Wrap"
                           Margin="12,-6,12,0"
                           Style="{StaticResource PhoneTextSubtleStyle}" />
            </StackPanel>
        </DataTemplate>
    </Application.Resources>

public class DataTemplateSelector : ContentControl
{
    protected override void OnContentChanged(object oldContent, object newContent)
    {
        if (newContent == null)
       {
           ContentTemplate = null;
        } else {
            var type = newContent.GetType();
            if (Application.Current.Resources.Contains(type.FullName))
            {
                ContentTemplate = App.Current.Resources[type.FullName] as DataTemplate;
            }
         }
    }
}

<ListBox x:Name="MainListBox"
		 Margin="0,0,-12,0"
	                 ItemsSource="{Binding CategoriesAndItems}"
		SelectionChanged="MainListBox_SelectionChanged">
	<ListBox.ItemTemplate>
		<DataTemplate>
			<TestGroupedList:DataTemplateSelector Content="{Binding}" />
		</DataTemplate>
	</ListBox.ItemTemplate>
</ListBox>

 var item = MainListBox.SelectedItem as ItemViewModel;
 if (item != null)
 {
  // Navigate to the new page
  NavigationService.Navigate(new Uri("/DetailsPage.xaml?Id=" + item.Id,
                                                   UriKind.Relative));

   // Reset selected index to -1 (no selection)
    MainListBox.SelectedIndex = -1;
}

public enum ExternalEnum
{
    Ready,
    SoftwareUpdate,
    HardwareUpdate,
    Error,
    TimeOut
}

public enum InternalEnum
{
    DatabaseReady,
    Maintenance,
    ServerError
}

public static class EnumExtensions
{
    public static InternalEnum ToInternalEnum(this ExternalEnum value)
    {
        switch (value)
        {
            case ExternalEnum.Ready:
                return InternalEnum.DatabaseReady;
            case ExternalEnum.HardwareUpdate:
            case ExternalEnum.SoftwareUpdate:
                return InternalEnum.Maintenance;
            case ExternalEnum.TimeOut:
            case ExternalEnum.Error:
                return InternalEnum.ServerError;
            default:
                throw new InvalidCastException("Unknown value for ExternalEnum value " + value);
        }
    }
}

ExternalEnum wsResult = ...;
return wsResult.ToInternalEnum();

# Downloads with BitsTransfer
function Get-Downloads {
  Import-Module BitsTransfer
  Get-BitsTransfer | % { "{0}: {2} {3:0.00} MB/{4:0.00} MB ( {1:0.00}% )" -f $_.DisplayName, $(100*$_.BytesTransferred/$_.BytesTotal), $_.JobState, ($_.BytesTransferred/1MB), ($_.BytesTotal/1MB) }
}
Set-Alias "dl" "Get-Downloads"

# Get a list of all downloads
function Complete-Downloads
{
  Import-Module BitsTransfer
  Get-BitsTransfer | ? { $_.JobState -eq "Transferred" } | Complete-BitsTransfer
}

# suspend all Downloads (optional all below a certain threshhold
function Suspend-Downloads( [int] $maxPercent = 100 )
{
  Complete-Downloads
  Get-BitsTransfer | ? { $_.JobState -eq "Transferring"  -and ($_.BytesTransferred/$_.BytesTotal) -lt ($maxPercent/100) } | Suspend-BitsTransfer
}

#resume all Downloads (optional all above a certain threshhold
function Resume-Downloads( [int] $minPercent = 0 )
{
  Complete-Downloads
  Get-BitsTransfer | ? { $_.JobState -eq "Suspended" -and ($_.BytesTransferred/$_.BytesTotal) -gt ($minPercent/100) } | Resume-BitsTransfer -Async
}

# download Mix Session Videos. Call it like mix "EX21" "CL01" "FT05"
function Mix()
{
  complete-downloads; $args | % { & $scripthome\get-Mix10Video.ps1 $_ } ; sleep -Seconds 5; get-downloads
}

#requires -version 2.0
PARAM (
   [Parameter(Position=1, Mandatory=$false)]
   [String]$Video="?",

   [Parameter(Position=2, Mandatory=$false)]
   [ValidateSet("wmv","wmv-hq","pptx", "mp4")]
   [String]$MediaType ="wmv-hq",

   [string]$Destination = "F:\Videos\Mix10",

   [string]$rss = "http://live.visitmix.com/Sessions/RSS"
)

Import-Module BitsTransfer

#$illegalChars = "[{0}]" -f ([Regex]::Escape([String] [System.IO.Path]::GetInvalidFileNameChars()))
$illegalChars = '[:*?\\\/\t\n<>|"]'

# Get Session RSS, parse Titel, Speaker, Tags, Description, ...
$wc = new-object System.Net.WebClient
$rssdata = [xml]$wc.DownloadString($rss)
$item = $rssdata.rss.channel.item | ? { $_.link.EndsWith($Video) }

Push-Location $Destination
$Extension = $(switch -wildcard($MediaType){"wmv*"{"wmv"} "mp4"{"mp4"} "pptx"{"pptx"}})
$SrcUrl = "http://ecn.channel9.msdn.com/o9/mix/10/{0}/{2}.{1}" -f  $MediaType, $Extension, $Video
$Destfile = ( "{0}-{1}.{2}" -f $Video, $Title, $Extension ) -replace $illegalChars, ""
$Destpath = $("{0}\{1}" -f $Destination, $Destfile)
$indexFile =  $("{0}\{1}" -f $Destination, "index.xml")

$Title = $item.title

# get index.xml
$index = new-object XML
$index.Load($indexFile)

# returns the list of the missing sessions if code is ? or item not found
# use filter like | ? { $_.tags -contains "WindowsPhone" } | % { .\Get-Mix10Video.ps $_.code }
if ( $Video -eq "?" -or $item -eq $null )
{
    $rssdata.rss.channel.item |  % {
         New-Object PsObject -Property @{
            code    = $_.link.Substring($_.link.LastIndexOf("/") +1 )
            title   = $_.title
            speaker = $_.author
            tags    = @( $_.category )
        }
    } | ? {
        $xpath = "//session[code='"+ $_.code +"']"
       $index.SelectSingleNode($xpath) -eq $null
    } | sort -Property "code"
    return
}

# does index already contains session?
$session = $index.SelectSingleNode("//session[code='$Video']")
if ($session -eq $null) {
  $firstSession = @( $index.sessions.session )[0]
  $session = $firstSession.Clone()
  $session.code = $Video
  [void]$index.sessions.AppendChild($session)
}

$session.title = $Title
$session.speaker = $item.author
$session.tags = $item.category  -join ","
$session.sessionref = $item.link
$session.local = $Destpath
$session.href = $SrcUrl
$session.description = $item.description

# remove dummy as it is no longer needed
$dummy = $session = $index.SelectSingleNode("//session[code='DMY00']")
if ($dummy -ne $null) { $index.sessions.RemoveChild( $dummy ) }

# sort sessions by code
[void] ( $index.sessions.session | sort -Property "code" | % { $index.sessions.RemoveChild($_); $index.sessions.AppendChild($_) } )

$index.Save($indexFile)

# file downloaded in former session?
if (Test-Path "$Video*.$Extension") {
  $title = "File $Video*.$Extension already exists!"
  $message = "Do you want to delete the existing file and download it new?"

  $yes = New-Object System.Management.Automation.Host.ChoiceDescription "&Yes", `
      "Delete $Destfile and start download"

  $continue = New-Object System.Management.Automation.Host.ChoiceDescription "&Continue", `
      "Continue without deleting file"

  $no = New-Object System.Management.Automation.Host.ChoiceDescription "&No", `
      "Hold file and skip download"

  $options = [System.Management.Automation.Host.ChoiceDescription[]]($yes, $continue, $no)

  $result = $host.ui.PromptForChoice($title, $message, $options, 2) 

  switch ($result)
    {
        0 { delete $Destpath }
        1 { "Continuing with download" }
        2 {
            Pop-Location
            return
          }
    }

}

#start download
[void] ( Start-BitsTransfer -Source $SrcUrl -Destination $Destpath -DisplayName ($Video +": "+$Title)  -Description $item.description -Async )

Pop-Location

Write-Host "You may now use Get-BitsTransfer to check on the status of the downloads. By default, failed transfers will be retried every 10 minutes for two weeks."

<?xml version="1.0" encoding="utf-8"?>
<!-- Sessionlist unter http://live.visitmix.com/Sessions/RSS brauchbar? -->
<sessions>
  <session>
    <code>CL01</code>
    <title>Changing our Game – an Introduction to Windows Phone 7 Series</title>
    <speaker>Joe Belfiore</speaker>
    <tags>Mobile, Windows Phone</tags>
    <href>http://ecn.channel9.msdn.com/o9/mix/10/wmv-hq/CL01.wmv</href>
    <sessionref>http://live.visitmix.com/MIX10/Sessions/CL01</sessionref>
    <local>CL01-Introduction to Windows Phone 7 Series.wmv</local>
    <description>
      Major changes are coming to Windows Phone! This session goes in-depth on the design and
      features of Windows Phone and gives a comprehensive picture of what’s
      coming in this exciting new release.
    </description>
    <filesize>
    </filesize>
    <length>
    </length>
  </session>
</sessions>

Technorati-Tags: PowerShell,MIX2010,MIX10,Videos,Sessions,Download,BitsTransfer