Un point sur une actualité .NET particulièrement dense ces derniers jours :

• Microsoft annonce le passage en Release Candidate de Windows AppFabric et la beta de Biztalk Server 2010, permettant de faire un pas de plus vers un véritable serveur d’application .NET ouvert sur l’extérieur et sur le cloud.
  
  AppFabric (anciennement “Dublin”) permet d’héberger et de monitorer des services WCF et des processus metiers Workflow Foundation. Il propose également un cache distribué (anciennement “Velocity”) permettant d’accélérer l’accès aux données pour les applications, ainsi que des facilités pour faire communiquer les applications internes de l’entreprise avec celles basées dans le Cloud avec Azure.
• Les versions finales des Silverlight 4 Tools et des RIA Services ont été annoncées Les Tools intégrent le développement Silverlight dans Visual Studio 2010. Les RIA Services facilitent la production d’applications métiers en Silverlight en proposant des solutions aux problèmatiques les plus communes (communication client / serveur, pagination, validation, filtrage…)
• Fluent NHibernate passe en version 1.1. Cette librairie permet de configurer NHibernate et de constituer les mappings par le code de manière plus fluide grâce aux expressions lambdas et au principe de Fluent Interface. Le processus de refactoring du code s’en trouve simplifié.

• Oren Eini (a.k.a. Ayende Rahien) annonce la sortie de RavenDB, une base de données orientée documents pour .NET. Une base NoSQL à surveiller !
• A voir : cette vidéo présentant quelques technologies et langages à surveiller de prêt. Même si la sélection est limitée et que qu’il ne s’agit que d’un survol sans exemple de code, l’intérêt se trouve dans le débat et dans les nombreuses ressources évoquées.
• Dans la même veine, ce post présente quatre librairies et techniques qui gagnent à être connues : MEF pour l’extensibilité, Reactive pour de nouvelles utilisations des événements, Tasks pour la programmation parallèle et les utilisations des “Dynamic” apparus avec .NET 4
• A voir également, deux vidéos de Scott Guthrie portant sur Visual Studio et ASP.NET 4
• Ce post présente une sélection d’outils pour débuter avec WPF, la partie du framework qui permet de libérer le potentiel des applications Desktop. Au menu : des éditeurs XAML, des débuggers, des outils graphiques…
• A signaler également l’apparition d’un outil de profiling pour les applications WPF dans le SDK de Windows
• Enfin, Jeffrey Palermo nous signale que contenu de son livre “ASP.NET MVC 2 in Action” est disponible sur GitHub. A récupérer d’urgence pour se plonger encore plus facilement dans l’alternative aux WebForms.

  A bientôt pour plus d’actu !

  • Partager:
  • Facebook

I just finished the first version of the "twitter viewer" in C# with WPF. I’ve some
layout modifications to be done but the application is ready.

Download the source (Visual Studio 2008 beta 2)

Download the application (unzip and launch the .exe file)

Some screenshots :

when the user clicks on an hyperlink : 

the settings page, username and password for the first version :

In my TwitterViewer in WPF I found that status can have urls in the body so they can’t
be bind directly to a TextBlock.
With a Converter I find maybe a good solution : Split the text with a regular expression,
build inline elements (simple Run for
text and Hyperlink for
urls) and put them in the Inlines property of the TextBlock :

<
Label
Margin
="8,0,8,0"
x
:
Name
="status"
Grid
.
Column
="1"
>


      <
Label
.
Content
>





<
Binding
Path
="Text"
Converter
="{StaticResource
urlConverter}"/>


       </
Label
.
Content
>


</
Label
>

And the code of the Converter implementation :

          String[] LinksText = Regex.Split((String)value, @"(\bhttp://[^
]+\b)"); TextBlock txtBlock = newTextBlock();
txtBlock.TextWrapping = System.Windows.TextWrapping.Wrap; foreach (String textSplit in LinksText)
{ if (textSplit.Length > 0) { if (textSplit.Substring(0,
1).Equals("h")) { Hyperlink textFormate
= newHyperlink(newRun(textSplit));
textFormate.NavigateUri = newUri(textSplit);
txtBlock.Inlines.Add(textFormate); } else  {
txtBlock.Inlines.Add(newRun(textSplit));
} } } return txtBlock;

I’ve read a lot of tutorials about databinding in WPF but often it’s all about XAML.
In my TwitterViewer
application in WPF I need to update the TwitterManager class with username
and password of the user. I choose to set the binding in code. Here is the constructor
of the main page :

          public MainPage() { InitializeComponent(); //create
a provider  odp = newObjectDataProvider();
odp.MethodName = "GetStatuses"; odp.ObjectInstance
= newTwitterManager("tewmgd", "xxxx");
odp.IsInitialLoadEnabled = false; Binding myBinding
= newBinding();
myBinding.Source = odp; //set the source of the
ItemsSource  statusList.SetBinding(ListView.ItemsSourceProperty,
myBinding); odp.Refresh(); }

With an  hyperLink the user can navigate to another page to change the settings
(username and password). The PageFunction control
allows the launching page to subscribe to the Return event and since it’s a generic
class, the return object is typesafe :

          void settingsLink_Click(object sender, RoutedEventArgs e)
{ //create a new instance of the settings page SettingsPage pageFunction
= newSettingsPage(); //subscribe
to the return event  pageFunction.Return += newReturnEventHandler<TwitterManager>

(OnSettingsReturned); this.NavigationService.Navigate(pageFunction);
}

          public
          void OnSettingsReturned(object sender,ReturnEventArgs<TwitterManager>
e) { //change the source of the provider  odp.ObjectInstance
= e.Result; //refresh the provider and with it the
listview  odp.Refresh(); }

In the target page the button event
handler uses the OnReturn method to navigate backward and set the result object :

          private
          void OnClickDone(object sender, RoutedEventArgs e)
{ OnReturn(newReturnEventArgs<TwitterManager>(
newTwitterManager(this.txtUserName.Text,this.txtPassword.Text)));
}

          Update, screenshoots of the two pages :
        

One of the hardest things in WPF it’s that there are many ways to reach the
same result. The same is true with other frameworks, but WPF and its language,
XAML, allow for some powerful and complex design with a large collection
of concepts : dependency properties , attached properties, control templates,
item templates, styles and so on… I’m currently writing a simple Twitter viewer
as a way to learn WPF. This "application" simply shows the xml-based feed of a user’s
friends through the API :

I created classes from the feed through the XSD schema generation tool (xsd.exe).
Be careful before splitting the generated classes, read the Serialization
section on MSDN :

A helper class creates an HTTP request with basic authentication to get the feed :

          //object to hold twitter response 
          Statuses statuses
= null; //request
to twitter service HttpWebRequest request
= (HttpWebRequest)
WebRequest.Create("http://twitter.com/statuses/friends_timeline.xml"); //authentication
info CredentialCache authInfo = newCredentialCache();
authInfo.Add(newUri(http://twitter.com/statuses/friends_timeline.xml),

"Basic", newNetworkCredential(username,
password)); request.Credentials = authInfo; //make
the call WebResponse response =
request.GetResponse(); //deserialize response XmlSerializer mySerializer
= newXmlSerializer(typeof(Statuses));
statuses = (Statuses)mySerializer.Deserialize(response.GetResponseStream());
response.Close(); listStatut = newList<Status>(statuses.status);

This method is called by the ObjectDataProvider which
provides the user and password :

          <
          ObjectDataProvider
           x
          :
          Key
          ="TwitterDataSource"
           d
          :
          IsDataSource
          ="True"
          
            

ObjectType
          ="{x:Type TwitterWPF:TwitterManager}"
           MethodName
          ="GetStatuses"> 
           <
          ObjectDataProvider
          .
          ConstructorParameters
          > 
           <
          sys
          :
          String
          >
          user
          </
          sys
          :
          String
          > 
           <
          sys
          :
          String
          >
          password
          </
          sys
          :
          String
          > 
           </
          ObjectDataProvider
          .
          ConstructorParameters
          >
          
          
          </
          ObjectDataProvider
          >
        

This class puts the collection returned in an ObservableCollection object
that provides notification when an item is added or removed. This can be useful
since we want to refresh the UI with a timer to get new statuses from Twitter.

I found severalarticles to
design items with alternate backgrounds in a ListView but
none works for me. They overwrite the style property of the items and they will
hide the background of the border. This border
is used to simulate rounded panels around the text :

          <
          ListView
          .
          ItemTemplate
          > 
          
          
          <
          DataTemplate
          >

          <
          Border
           Width
          ="400"
           Height
          ="75"
           CornerRadius
          ="10,10,10,10"
           Margin
          ="4,4,4,4"
          
            

Padding
          ="4,4,4,4" 
          Background
          ="{Binding
RelativeSource={RelativeSource AncestorType=ListViewItem},

Converter={StaticResource backgroundConverter}}"> 
          
          
          <
          Grid
           x
          :
          Name
          ="statusBox"
           Height
          ="auto"
           Width
          ="auto"> 
          
          
          <
          Grid
          .
          ColumnDefinitions
          > 
          
          
          <
          ColumnDefinition
           Width
          ="0.168*"
/> 
          
          
          <
          ColumnDefinition
           Width
          ="0.832*"
/> 
          
          
          </
          Grid
          .
          ColumnDefinitions
          > 
          
          
          <
          Grid
          .
          RowDefinitions
          > 
          
          
          <
          RowDefinition
          />
          
          
          </
          Grid
          .
          RowDefinitions
          >
          
          
          <
          Image
           Source
          ="{Binding
Path=User.ProfileImageUrl}"
          
            

Grid
          .
          Column
          ="0"
           Grid
          .
          Row
          ="0"
           x
          :
          Name
          ="userImage"/>
          
          
          <
          Label
           Margin
          ="8,0,8,0"
           x
          :
          Name
          ="status"
           Grid
          .
          Column
          ="1"
> 
          
          
          <
          TextBlock
           TextWrapping
          ="WrapWithOverflow"
          
            

Text
          ="{Binding Path=Text}"></
          TextBlock
          > 
          
          
          </
          Label
          >
          
          
          </
          Grid
          > 
          
          
          </
          Border
          > 
          
          
          </
          DataTemplate
          > 
          </
          ListView
          .
          ItemTemplate
          >
        

So I built an implementation of IValueConverter to
convert the binding of the background value property. I need to know the current ListViewItem,
so I provide the ancestor of type ListViewItem as the object to be converted. The
converter class finds its index inside the ListView and returns the color accordingly
:

          public
          object Convert(object value, Type targetType,

object parameter, System.Globalization.CultureInfo culture)
{ ListViewItem item = (ListViewItem)value; ListView listView
= ItemsControl.ItemsControlFromItemContainer(item) asListView; //
Get the index of a ListViewItem int index
= listView.ItemContainerGenerator.IndexFromContainer(item); if (index
% 2 == 0) { returnBrushes.LightBlue;
} else  { returnBrushes.Beige;
} }

The last thing to add is the call to refresh the list of the statuses : I put
a timer that refreshes both the  ObjectDataProvider and the ListView (without
the latter the index property is not correctly returned in the converter method) :

          void TimerClock_Tick(object sender, EventArgs e)
{ ObjectDataProvider odp = Resources["TwitterDataSource"] asObjectDataProvider;
odp.Refresh(); ICollectionView dataView
= CollectionViewSource.GetDefaultView(statusList.ItemsSource);
dataView.Refresh(); }

As I said, there are surely other ways to do this, maybe even more efficiently.
But the Twitter API returning only the 20 latest statuses,  efficiently is not
an issue. And it’s a good thing because I’m still discovering the WPF world.

download
the Visual Studio Orcas solution (beta1).