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• Receiving "expected expression before" Error When Using A Struct

  - by Zach Dziura

  I'm in the process of creating a simple 2D game engine in C with a group of friends at school. I'd like to write this engine in an Object-Oriented way, using structs as classes, function pointers as methods, etc. To emulate standard OOP syntax, I created a create() function which allocates space in memory for the object. I'm in the process of testing it out, and I'm receiving an error. Here is my code for two files that I'm using to test: test.c: #include <stdio.h> int main() { typedef struct { int i; } Class; Class *test = (Class*) create(Class); test->i = 1; printf("The value of \"test\" is: %i\n", test->i); return 0; } utils.c: #include <stdio.h> #include <stdlib.h> #include "utils.h" void* create(const void* class) { void *obj = (void*) malloc(sizeof(class)); if (obj == 0) { printf("Error allocating memory.\n"); return (int*) -1; } else { return obj; } } void destroy(void* object) { free(object); } The utils.h file simply holds prototypes for the create() and destroy() functions. When I execute gcc test.c utils.c -o test, I'm receiving this error message: test.c: In function 'main': test.c:10:32: error: expected expression before 'Class' I know it has something to do with my typedef at the beginning, and how I'm probably not using proper syntax. But I have no idea what that proper syntax is. Can anyone help?

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• C++: Delete a struct?

  - by Rosarch

  I have a struct that contains pointers: struct foo { char* f; int* d; wchar* m; } I have a vector of shared pointers to these structs: vector<shared_ptr<foo>> vec; vec is allocated on the stack. When it passes out of scope at the end of the method, its destructor will be called. (Right?) That will in turn call the destructor of each element in the vector. (Right?) Does calling delete foo delete just the pointers such as foo.f, or does it actually free the memory from the heap?

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• Dynamic Array of Objects Sans Vector Class

  - by Connor Black

  I am doing a homework assignment for my summer OO class and we need to write two classes. One is called Sale and the other is called Register. I've written my Sale class; here's the .h file: enum ItemType {BOOK, DVD, SOFTWARE, CREDIT}; class Sale { public: Sale(); // default constructor, // sets numerical member data to 0 void MakeSale(ItemType x, double amt); ItemType Item(); // Returns the type of item in the sale double Price(); // Returns the price of the sale double Tax(); // Returns the amount of tax on the sale double Total(); // Returns the total price of the sale void Display(); // outputs sale info private: double price; // price of item or amount of credit double tax; // amount of sales tax double total; // final price once tax is added in. ItemType item; // transaction type }; For the Register class we need to include a dynamic array of Sale objects in our member data. We cannot use the vector class. How is this done? Here's my 'Register' '.h' class Register{ public: Register(int ident, int amount); ~Register(); int GetID(){return identification;} int GetAmount(){return amountMoney;} void RingUpSale(ItemType item, int basePrice); void ShowLast(); void ShowAll(); void Cancel(); int SalesTax(int n); private: int identification; int amountMoney; };

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• How is covariance cooler than polymorphism...and not redundant?

  - by P.Brian.Mackey

  .NET 4 introduces covariance. I guess it is useful. After all, MS went through all the trouble of adding it to the C# language. But, why is Covariance more useful than good old polymorphism? I wrote this example to understand why I should implement Covariance, but I still don't get it. Please enlighten me. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Sample { class Demo { public delegate void ContraAction<in T>(T a); public interface IContainer<out T> { T GetItem(); void Do(ContraAction<T> action); } public class Container<T> : IContainer<T> { private T item; public Container(T item) { this.item = item; } public T GetItem() { return item; } public void Do(ContraAction<T> action) { action(item); } } public class Shape { public void Draw() { Console.WriteLine("Shape Drawn"); } } public class Circle:Shape { public void DrawCircle() { Console.WriteLine("Circle Drawn"); } } public static void Main() { Circle circle = new Circle(); IContainer<Shape> container = new Container<Circle>(circle); container.Do(s => s.Draw());//calls shape //Old school polymorphism...how is this not the same thing? Shape shape = new Circle(); shape.Draw(); } } }

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• Why are my thread being terminated ?

  - by Sephy

  Hi, I'm trying to repeat calls to methods through 3 differents threads. But after I start my threads, during the next iteration of my loop, they are all terminated so nothing is executed... The code is as follows : public static void main(String[] args) { main = new Main(); pollingThread.start(); } static Thread pollingThread = new Thread() { @Override public void run() { while (isRunning) { main.poll(); // test the state of the threads try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } }; }; public void poll() { if (clientThread == null) { clientThread = new Thread(new Runnable() { @Override public void run() { //create some objects } }); clientThread.start(); } else if (clientThread.isAlive()) { // do some treatment } if (gestionnaireThread == null) { gestionnaireThread = new Thread(new Runnable() { @Override public void run() { //create some objects }; }); gestionnaireThread.start(); } else if (gestionnaireThread.isAlive()) { // do some treatment } if (marchandThread == null) { marchandThread = new Thread(new Runnable() { @Override public void run() { // create some objects }; }); marchandThread.start(); } else if (marchandThread.isAlive()) { // do some treatment } } And for some reason, when I test the state of my different threads, they appear as runnable and then a the 2nd iteration, they are all terminated... What am I doing wrong? I actually have no error, but the threads are terminated and so my loop keeps looping and telling me the threads are terminated.... Thanks for any help.

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• wifi provider onLocationChanged is never called

  - by Kelsie

  I got a weird problem. I uses wifi to retrieve user location. I have tested on several phones; on some of them, I could never get a location update. it seemed that the method onLocationChanged is never called. My code is attached below.. Any suggestions appreciated!!! @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); LocationManager locationManager; locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE); String provider = locationManager.NETWORK_PROVIDER; Location l = locationManager.getLastKnownLocation(provider); updateWithNewLocation(l); locationManager.requestLocationUpdates(provider, 0, 0, locationListener); } private void updateWithNewLocation(Location location) { TextView myLocationText; myLocationText = (TextView)findViewById(R.id.myLocationText); String latLongString = "No location found"; if (location != null) { double lat = location.getLatitude(); double lng = location.getLongitude(); latLongString = "Lat:" + lat + "\nLong:" + lng; } myLocationText.setText("Your Current Position is:\n" + latLongString); } private final LocationListener locationListener = new LocationListener() { public void onLocationChanged(Location location) { updateWithNewLocation(location); Log.i("onLocationChanged", "onLocationChanged"); Toast.makeText(getApplicationContext(), "location changed", Toast.LENGTH_SHORT).show(); } public void onProviderDisabled(String provider) {} public void onProviderEnabled(String provider) {} public void onStatusChanged(String provider, int status, Bundle extras) {} }; Manifest <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/> <uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/> <uses-permission android:name="android.permission.INTERNET"/>

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• Silverlight Recruiting Application Part 6 - Adding an Interview Scheduling Module/View

  Between the last post and this one I went ahead and carried the ideas for the Jobs module and view into the Applicants module and view- they're both doing more or less the same thing, except with different objects being at their core.  Made for an easy cut-and-paste operation with a few items being switched from one to another.  Now that we have the ability to add postings and applicants, wouldn't it be nice if we could schedule an interview?  Of course it would! Scheduling Module I think you get the drift from previous posts that these project structures start looking somewhat similar.  The interview scheduling module is no different than the rest- it gets a SchedulingModule.cs file at the root that inherits from IModule, and there is a single SchedulerView.xsml and SchedulerViewModel.cs setup for our V+VM.  We have one unique concern as we enter into this- RadScheduler deals with AppointmentsSource, not ItemsSource, so there are some special considerations to take into account when planning this module. First, I need something which inherits from AppointmentBase.  This is the core of the RadScheduler appointment, and if you are planning to do any form of custom appointment, you'll want it to inherit from this.  Then you can add-on functionality as needed.  Here is my addition to the mix, the InterviewAppointment: 01.public class InterviewAppointment : AppointmentBase 02.{ 03.    private int _applicantID; 04.    public int ApplicantID 05.    { 06.        get { return this._applicantID; } 07.        set 08.        { 09.            if (_applicantID != value) 10.            { 11.                _applicantID = value; 12.                OnPropertyChanged("ApplicantID"); 13.            } 14.        } 15.    } 16.   17.    private int _postingID; 18.    public int PostingID 19.    { 20.        get { return _postingID; } 21.        set 22.        { 23.            if (_postingID != value) 24.            { 25.                _postingID = value; 26.                OnPropertyChanged("PostingID"); 27.            } 28.        } 29.    } 30.   31.    private string _body; 32.    public string Body 33.    { 34.        get { return _body; } 35.        set 36.        { 37.            if (_body != value) 38.            { 39.                _body = value; 40.                OnPropertyChanged("Body"); 41.            } 42.        } 43.    } 44.   45.    private int _interviewID; 46.    public int InterviewID 47.    { 48.        get { return _interviewID; } 49.        set 50.        { 51.            if (_interviewID != value) 52.            { 53.                _interviewID = value; 54.                OnPropertyChanged("InterviewID"); 55.            } 56.        } 57.    } 58.   59.    public override IAppointment Copy() 60.    { 61.        IAppointment appointment = new InterviewAppointment(); 62.        appointment.CopyFrom(this);             63.        return appointment; 64.    } 65.   66.    public override void CopyFrom(IAppointment other) 67.    {             68.        base.CopyFrom(other); 69.        var appointment = other as InterviewAppointment; 70.        if (appointment != null) 71.        { 72.            ApplicantID = appointment.ApplicantID; 73.            PostingID = appointment.PostingID; 74.            Body = appointment.Body; 75.            InterviewID = appointment.InterviewID; 76.        } 77.    } 78.} Nothing too exciting going on here, we just make sure that our custom fields are persisted (specifically set in CopyFrom at the bottom) and notifications are fired- otherwise this ends up exactly like the standard appointment as far as interactions, etc.  But if we've got custom appointment items... that also means we need to customize what our appointment dialog window will look like. Customizing the Edit Appointment Dialog This initially sounds a lot more intimidating than it really is.  The first step here depends on what you're dealing with for theming, but for ease of everything I went ahead and extracted my templates in Blend for RadScheduler so I could modify it as I pleased.  For the faint of heart, the RadScheduler template is a few thousand lines of goodness since there are some very complex things going on in that control.  I've gone ahead and trimmed down the template parts I don't need as much as possible, so what is left is all that is relevant to the Edit Appointment Dialog.  Here's the resulting Xaml, with line numbers, so I can explain further: 001.<UserControl.Resources> 002.    <!-- begin Necessary Windows 7 Theme Resources for EditAppointmentTemplate --> 003.    <helpers:DataContextProxy x:Key="DataContextProxy" /> 004.       005.    <telerik:Windows7Theme x:Key="Theme" /> 006.    <SolidColorBrush x:Key="DialogWindowBackground" 007.                     Color="White" /> 008.    <SolidColorBrush x:Key="CategorySelectorBorderBrush" 009.                     Color="#FFB1B1B1" /> 010.    <LinearGradientBrush x:Key="RadToolBar_InnerBackground" 011.                         EndPoint="0.5,1" 012.                         StartPoint="0.5,0"> 013.        <GradientStop Color="#FFFDFEFF" 014.                      Offset="0" /> 015.        <GradientStop Color="#FFDDE9F7" 016.                      Offset="1" /> 017.        <GradientStop Color="#FFE6F0FA" 018.                      Offset="0.5" /> 019.        <GradientStop Color="#FFDCE6F4" 020.                      Offset="0.5" /> 021.    </LinearGradientBrush> 022.    <Style x:Key="FormElementTextBlockStyle" 023.           TargetType="TextBlock"> 024.        <Setter Property="HorizontalAlignment" 025.                Value="Right" /> 026.        <Setter Property="VerticalAlignment" 027.                Value="Top" /> 028.        <Setter Property="Margin" 029.                Value="15, 15, 0, 2" /> 030.    </Style> 031.    <Style x:Key="FormElementStyle" 032.           TargetType="FrameworkElement"> 033.        <Setter Property="Margin" 034.                Value="10, 10, 0, 2" /> 035.    </Style> 036.    <SolidColorBrush x:Key="GenericShallowBorderBrush" 037.                     Color="#FF979994" /> 038.    <telerik:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" /> 039.    <telerikScheduler:ImportanceToBooleanConverter x:Key="ImportanceToBooleanConverter" /> 040.    <telerikScheduler:NullToVisibilityConverter x:Key="NullToVisibilityConverter" /> 041.    <telerikScheduler:InvertedNullToVisibilityConverter x:Key="InvertedNullToVisibilityConverter" /> 042.    <scheduler:ResourcesSeparatorConverter x:Key="ResourcesSeparatorConverter" /> 043.    <DataTemplate x:Key="IconDataEditTemplate"> 044.        <Image Source="/Telerik.Windows.Controls.Scheduler;component/Themes/Office/Images/cal.png" 045.               Margin="3,3,0,0" 046.               Width="16" 047.               Height="16" /> 048.    </DataTemplate> 049.    <DataTemplate x:Key="SingleSelectionTemplate"> 050.        <Grid VerticalAlignment="Stretch" 051.              HorizontalAlignment="Stretch"> 052.            <Grid.RowDefinitions> 053.                <RowDefinition Height="Auto" /> 054.            </Grid.RowDefinitions> 055.            <Grid.ColumnDefinitions> 056.                <ColumnDefinition Width="Auto" 057.                                  MinWidth="84" /> 058.                <ColumnDefinition Width="Auto" 059.                                  MinWidth="200" /> 060.            </Grid.ColumnDefinitions> 061.            <TextBlock x:Name="SelectionNameLabel" 062.                       Margin="0,13,4,2" 063.                       Text="{Binding ResourceType.DisplayName}" 064.                       Style="{StaticResource FormElementTextBlockStyle}" 065.                       Grid.Column="0" /> 066.            <telerikInput:RadComboBox ItemsSource="{Binding ResourceItems}" 067.                                      Width="185" 068.                                      Margin="5,10,20,2" 069.                                      HorizontalAlignment="Left" 070.                                      Grid.Column="1" 071.                                      ClearSelectionButtonVisibility="Visible" 072.                                      ClearSelectionButtonContent="Clear All" 073.                                      DisplayMemberPath="Resource.DisplayName" 074.                                      telerik:StyleManager.Theme="{StaticResource Theme}" 075.                                      SelectedItem="{Binding SelectedItem, Mode=TwoWay}" /> 076.        </Grid> 077.    </DataTemplate> 078.    <DataTemplate x:Key="MultipleSelectionTemplate"> 079.        <Grid VerticalAlignment="Stretch" 080.              HorizontalAlignment="Stretch"> 081.            <Grid.RowDefinitions> 082.                <RowDefinition Height="Auto" /> 083.            </Grid.RowDefinitions> 084.            <Grid.ColumnDefinitions> 085.                <ColumnDefinition Width="Auto" 086.                                  MinWidth="84" /> 087.                <ColumnDefinition Width="Auto" 088.                                  MinWidth="200" /> 089.            </Grid.ColumnDefinitions> 090.            <TextBlock x:Name="SelectionNameLabel" 091.                       Grid.Column="0" 092.                       Text="{Binding ResourceType.DisplayName}" 093.                       Margin="0,13,4,2" 094.                       Style="{StaticResource FormElementTextBlockStyle}" /> 095.            <telerikInput:RadComboBox Grid.Column="1" 096.                                      Width="185" 097.                                      HorizontalAlignment="Left" 098.                                      Margin="5,10,20,2" 099.                                      ItemsSource="{Binding ResourceItems}" 100.                                      SelectedIndex="{Binding SelectedIndex, Mode=TwoWay}" 101.                                      ClearSelectionButtonVisibility="Visible" 102.                                      ClearSelectionButtonContent="Clear All" 103.                                      telerik:StyleManager.Theme="{StaticResource Theme}"> 104.                <telerikInput:RadComboBox.ItemTemplate> 105.                    <DataTemplate> 106.                        <Grid HorizontalAlignment="Stretch" 107.                              VerticalAlignment="Stretch"> 108.                            <CheckBox VerticalAlignment="Center" 109.                                      HorizontalContentAlignment="Stretch" 110.                                      VerticalContentAlignment="Center" 111.                                      IsChecked="{Binding IsChecked, Mode=TwoWay}" 112.                                      Content="{Binding Resource.DisplayName}"> 113.                                <CheckBox.ContentTemplate> 114.                                    <DataTemplate> 115.                                        <TextBlock HorizontalAlignment="Stretch" 116.                                                   VerticalAlignment="Stretch" 117.                                                   Text="{Binding Content, RelativeSource={RelativeSource TemplatedParent}}" /> 118.                                    </DataTemplate> 119.                                </CheckBox.ContentTemplate> 120.                            </CheckBox> 121.                        </Grid> 122.                    </DataTemplate> 123.                </telerikInput:RadComboBox.ItemTemplate> 124.            </telerikInput:RadComboBox> 125.        </Grid> 126.    </DataTemplate> 127.    <scheduler:ResourceTypeTemplateSelector x:Key="ItemTemplateSelector" 128.                                            MultipleSelectionTemplate="{StaticResource MultipleSelectionTemplate}" 129.                                            SingleSelectionTemplate="{StaticResource SingleSelectionTemplate}" /> 130.    <!-- end Necessary Windows 7 Theme Resources for EditAppointmentTemplate -->  131.       132.    <ControlTemplate x:Key="EditAppointmentTemplate" 133.                     TargetType="telerikScheduler:AppointmentDialogWindow"> 134.        <StackPanel Background="{TemplateBinding Background}" 135.                    UseLayoutRounding="True"> 136.            <StackPanel Grid.Row="0" 137.                        Orientation="Horizontal" 138.                        Background="{StaticResource RadToolBar_InnerBackground}" 139.                        Grid.ColumnSpan="2" 140.                        Height="0"> 141.                <!-- Recurrence buttons --> 142.                <Border Margin="1,1,0,0" 143.                        Background="#50000000" 144.                        HorizontalAlignment="Left" 145.                        VerticalAlignment="Center" 146.                        Width="2" 147.                        Height="16"> 148.                    <Border Margin="0,0,1,1" 149.                            Background="#80FFFFFF" 150.                            HorizontalAlignment="Left" 151.                            Width="1" /> 152.                </Border> 153.                <Border Margin="1,1,0,0" 154.                        Background="#50000000" 155.                        HorizontalAlignment="Left" 156.                        VerticalAlignment="Center" 157.                        Width="2" 158.                        Height="16"> 159.                    <Border Margin="0,0,1,1" 160.                            Background="#80FFFFFF" 161.                            HorizontalAlignment="Left" 162.                            Width="1" /> 163.                </Border> 164.                <TextBlock telerik:LocalizationManager.ResourceKey="ShowAs" 165.                           VerticalAlignment="Center" 166.                           Margin="5,0,0,0" /> 167.                <telerikInput:RadComboBox ItemsSource="{TemplateBinding TimeMarkers}" 168.                                          Width="100" 169.                                          Height="20" 170.                                          VerticalAlignment="Center" 171.                                          Margin="5,0,0,0" 172.                                          ClearSelectionButtonVisibility="Visible" 173.                                          ClearSelectionButtonContent="Clear" 174.                                          SelectedItem="{Binding TimeMarker,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" 175.                                          telerik:StyleManager.Theme="{StaticResource Theme}"> 176.                    <telerikInput:RadComboBox.ItemTemplate> 177.                        <DataTemplate> 178.                            <StackPanel Orientation="Horizontal"> 179.                                <Rectangle Fill="{Binding TimeMarkerBrush}" 180.                                           Margin="2" 181.                                           Width="12" 182.                                           Height="12" /> 183.                                <TextBlock Text="{Binding TimeMarkerName}" 184.                                           Margin="2" /> 185.                            </StackPanel> 186.                        </DataTemplate> 187.                    </telerikInput:RadComboBox.ItemTemplate> 188.                </telerikInput:RadComboBox> 189.                <telerik:RadToggleButton x:Name="High" 190.                                         BorderThickness="0" 191.                                         Background="{StaticResource RadToolBar_InnerBackground}" 192.                                         DataContext="{TemplateBinding EditedAppointment}" 193.                                         telerik:StyleManager.Theme="{StaticResource Theme}" 194.                                         IsChecked="{Binding Importance,Mode=TwoWay, Converter={StaticResource ImportanceToBooleanConverter},ConverterParameter=High}" 195.                                         Margin="2,2,0,2" 196.                                         Width="23" 197.                                         Height="23" 198.                                         HorizontalContentAlignment="Center" 199.                                         ToolTipService.ToolTip="High importance" 200.                                         CommandParameter="High" 201.                                         Command="telerikScheduler:RadSchedulerCommands.SetAppointmentImportance"> 202.                    <StackPanel HorizontalAlignment="Center"> 203.                        <Path Stretch="Fill" 204.                              Height="10" 205.                              HorizontalAlignment="Center" 206.                              VerticalAlignment="Top" 207.                              Width="5.451" 208.                              Data="M200.39647,58.840393 C200.39337,58.336426 201.14566,57.683922 202.56244,57.684292 C204.06589,57.684685 204.73764,58.357765 204.72783,58.992363 C205.04649,61.795574 203.04713,64.181099 202.47388,66.133446 C201.93753,64.154961 199.9471,61.560352 200.39647,58.840393 z"> 209.                            <Path.Fill> 210.                                <LinearGradientBrush EndPoint="1.059,0.375" 211.                                                     StartPoint="-0.457,0.519"> 212.                                    <GradientStop Color="#FFFF0606" 213.                                                  Offset="0.609" /> 214.                                    <GradientStop Color="#FFBF0303" 215.                                                  Offset="0.927" /> 216.                                </LinearGradientBrush> 217.                            </Path.Fill> 218.                        </Path> 219.                        <Ellipse Height="3" 220.                                 HorizontalAlignment="Center" 221.                                 Margin="0,-1,0,0" 222.                                 VerticalAlignment="Top" 223.                                 Width="3"> 224.                            <Ellipse.Fill> 225.                                <RadialGradientBrush> 226.                                    <GradientStop Color="#FFFF0606" 227.                                                  Offset="0" /> 228.                                    <GradientStop Color="#FFBF0303" 229.                                                  Offset="1" /> 230.                                </RadialGradientBrush> 231.                            </Ellipse.Fill> 232.                        </Ellipse> 233.                    </StackPanel> 234.                </telerik:RadToggleButton> 235.                <telerik:RadToggleButton x:Name="Low" 236.                                         HorizontalContentAlignment="Center" 237.                                         BorderThickness="0" 238.                                         Background="{StaticResource RadToolBar_InnerBackground}" 239.                                         DataContext="{TemplateBinding EditedAppointment}" 240.                                         IsChecked="{Binding Importance,Mode=TwoWay, Converter={StaticResource ImportanceToBooleanConverter},ConverterParameter=Low}" 241.                                         Margin="0,2,0,2" 242.                                         Width="23" 243.                                         Height="23" 244.                                         ToolTipService.ToolTip="Low importance" 245.                                         CommandParameter="Low" 246.                                         telerik:StyleManager.Theme="{StaticResource Theme}" 247.                                         Command="telerikScheduler:RadSchedulerCommands.SetAppointmentImportance"> 248.                    <Path Stretch="Fill" 249.                          Height="12" 250.                          HorizontalAlignment="Center" 251.                          VerticalAlignment="Top" 252.                          Width="9" 253.                          Data="M222.40353,60.139881 L226.65768,60.139843 L226.63687,67.240196 L229.15347,67.240196 L224.37816,71.394943 L219.65274,67.240196 L222.37572,67.219345 z" 254.                          Stroke="#FF0365A7"> 255.                        <Path.Fill> 256.                            <LinearGradientBrush EndPoint="1.059,0.375" 257.                                                 StartPoint="-0.457,0.519"> 258.                                <GradientStop Color="#FFBBE4FF" /> 259.                                <GradientStop Color="#FF024572" 260.                                              Offset="0.836" /> 261.                                <GradientStop Color="#FF43ADF4" 262.                                              Offset="0.466" /> 263.                            </LinearGradientBrush> 264.                        </Path.Fill> 265.                    </Path> 266.                </telerik:RadToggleButton> 267.            </StackPanel > 268.            <Border DataContext="{TemplateBinding EditedAppointment}" 269.                    Background="{Binding Category.CategoryBrush}" 270.                    Visibility="{Binding Category,Converter={StaticResource NullToVisibilityConverter}}" 271.                    CornerRadius="3" 272.                    Height="20" 273.                    Margin="5,10,5,0"> 274.                <TextBlock Text="{Binding Category.DisplayName}" 275.                           VerticalAlignment="Center" 276.                           Margin="5,0,0,0" /> 277.            </Border> 278.            <Grid VerticalAlignment="Stretch" 279.                  HorizontalAlignment="Stretch" 280.                  DataContext="{TemplateBinding EditedAppointment}" 281.                  Background="{TemplateBinding Background}"> 282.                <Grid.RowDefinitions> 283.                    <RowDefinition Height="Auto" /> 284.                    <RowDefinition Height="Auto" /> 285.                    <RowDefinition Height="Auto" /> 286.                    <RowDefinition Height="Auto" /> 287.                    <RowDefinition Height="Auto" /> 288.                    <RowDefinition Height="Auto" /> 289.                    <RowDefinition Height="Auto" /> 290.                    <RowDefinition Height="Auto" /> 291.                    <RowDefinition Height="Auto" /> 292.                    <RowDefinition Height="Auto" /> 293.                </Grid.RowDefinitions> 294.                <Grid.ColumnDefinitions> 295.                    <ColumnDefinition Width="Auto" 296.                                      MinWidth="100" /> 297.                    <ColumnDefinition Width="Auto" 298.                                      MinWidth="200" /> 299.                </Grid.ColumnDefinitions> 300.                <!-- Subject --> 301.                <TextBlock x:Name="SubjectLabel" 302.                           Grid.Row="0" 303.                           Grid.Column="0" 304.                           Margin="0,15,0,2" 305.                           telerik:LocalizationManager.ResourceKey="Subject" 306.                           Style="{StaticResource FormElementTextBlockStyle}" /> 307.                <TextBox x:Name="Subject" 308.                         Grid.Row="0" 309.                         Grid.Column="1" 310.                         MinHeight="22" 311.                         Padding="4 2" 312.                         Width="340" 313.                         HorizontalAlignment="Left" 314.                         Text="{Binding Subject, Mode=TwoWay}" 315.                         MaxLength="255" 316.                         telerik:StyleManager.Theme="{StaticResource Theme}" 317.                         Margin="10,12,20,2" /> 318.                <!-- Description --> 319.                <TextBlock x:Name="DescriptionLabel" 320.                           Grid.Row="1" 321.                           Grid.Column="0" 322.                           Margin="0,13,0,2" 323.                           telerik:LocalizationManager.ResourceKey="Body" 324.                           Style="{StaticResource FormElementTextBlockStyle}" /> 325.                <TextBox x:Name="Body" 326.                         VerticalAlignment="top" 327.                         Grid.Row="1" 328.                         Grid.Column="1" 329.                         Height="Auto" 330.                         MaxHeight="82" 331.                         Width="340" 332.                         HorizontalAlignment="Left" 333.                         MinHeight="22" 334.                         Padding="4 2" 335.                         TextWrapping="Wrap" 336.                         telerik:StyleManager.Theme="{StaticResource Theme}" 337.                         Text="{Binding Body, Mode=TwoWay}" 338.                         AcceptsReturn="true" 339.                         Margin="10,10,20,2" 340.                         HorizontalScrollBarVisibility="Auto" 341.                         VerticalScrollBarVisibility="Auto" /> 342.                <!-- Start/End date --> 343.                <TextBlock x:Name="StartDateLabel" 344.                           Grid.Row="2" 345.                           Grid.Column="0" 346.                           Margin="0,13,0,2" 347.                           telerik:LocalizationManager.ResourceKey="StartTime" 348.                           Style="{StaticResource FormElementTextBlockStyle}" /> 349.                <telerikScheduler:DateTimePicker x:Name="StartDateTime" 350.                                                 Height="22" 351.                                                 Grid.Row="2" 352.                                                 Grid.Column="1" 353.                                                 HorizontalAlignment="Left" 354.                                                 Margin="10,10,20,2" 355.                                                 Style="{StaticResource FormElementStyle}" 356.                                                 SelectedDateTime="{Binding Start, Mode=TwoWay}" 357.                                                 telerikScheduler:StartEndDatePicker.EndPicker="{Binding ElementName=EndDateTime}" 358.                                                 IsTabStop="False" 359.                                                 IsEnabled="False" /> 360.                <TextBlock x:Name="EndDateLabel" 361.                           Grid.Row="3" 362.                           Grid.Column="0" 363.                           Margin="0,13,0,2" 364.                           telerik:LocalizationManager.ResourceKey="EndTime" 365.                           Style="{StaticResource FormElementTextBlockStyle}" /> 366.                <telerikScheduler:DateTimePicker x:Name="EndDateTime" 367.                                                 Height="22" 368.                                                 Grid.Row="3" 369.                                                 Grid.Column="1" 370.                                                 HorizontalAlignment="Left" 371.                                                 Margin="10,10,20,2" 372.                                                 Style="{StaticResource FormElementStyle}" 373.                                                 IsTabStop="False" 374.                                                 IsEnabled="False" 375.                                                 SelectedDateTime="{Binding End, Mode=TwoWay}" /> 376.                <!-- Is-all-day selector --> 377.                <CheckBox x:Name="AllDayEventCheckbox" 378.                          IsChecked="{Binding IsAllDayEvent, Mode=TwoWay}" 379.                          Grid.Row="4" 380.                          Grid.Column="1" 381.                          Margin="10,10,20,2" 382.                          HorizontalAlignment="Left" 383.                          telerik:StyleManager.Theme="{StaticResource Theme}" 384.                          telerik:LocalizationManager.ResourceKey="AllDayEvent"> 385.                    <telerik:CommandManager.InputBindings> 386.                        <telerik:InputBindingCollection> 387.                            <telerik:MouseBinding Command="telerikScheduler:RadSchedulerCommands.ChangeTimePickersVisibility" 388.                                                  Gesture="LeftClick" /> 389.                        </telerik:InputBindingCollection> 390.                    </telerik:CommandManager.InputBindings> 391.                </CheckBox> 392.                <Grid Grid.Row="5" 393.                      Grid.ColumnSpan="2"> 394.                    <Grid.ColumnDefinitions> 395.                        <ColumnDefinition Width="Auto" 396.                                          MinWidth="100" /> 397.                        <ColumnDefinition Width="Auto" 398.                                          MinWidth="200" /> 399.                    </Grid.ColumnDefinitions> 400.                    <Grid.RowDefinitions> 401.                        <RowDefinition Height="Auto" /> 402.                        <RowDefinition Height="Auto" /> 403.                    </Grid.RowDefinitions> 404.                    <TextBlock Text="Applicant" 405.                               Margin="0,13,0,2" 406.                               Style="{StaticResource FormElementTextBlockStyle}" /> 407.                    <telerikInput:RadComboBox IsEditable="False" 408.                                              Grid.Column="1" 409.                                              Height="24" 410.                                              VerticalAlignment="Center" 411.                                              ItemsSource="{Binding Source={StaticResource DataContextProxy}, Path=DataSource.ApplicantList}" 412.                                              SelectedValue="{Binding ApplicantID, Mode=TwoWay}" 413.                                              SelectedValuePath="ApplicantID" 414.                                              DisplayMemberPath="FirstName" /> 415.                       416.                    <TextBlock Text="Job" 417.                               Margin="0,13,0,2" 418.                               Grid.Row="1" 419.                               Style="{StaticResource FormElementTextBlockStyle}" /> 420.                    <telerikInput:RadComboBox IsEditable="False" 421.                                              Grid.Column="1" 422.                                              Grid.Row="1" 423.                                              Height="24" 424.                                              VerticalAlignment="Center" 425.                                              ItemsSource="{Binding Source={StaticResource DataContextProxy}, Path=DataSource.JobsList}" 426.                                              SelectedValue="{Binding PostingID, Mode=TwoWay}" 427.                                              SelectedValuePath="PostingID" 428.                                              DisplayMemberPath="JobTitle"/> 429.                </Grid> 430.                    <!-- Resources --> 431.                <Grid x:Name="ResourcesLayout" 432.                      Grid.Row="7" 433.                      Grid.Column="0" 434.                      Grid.ColumnSpan="2" 435.                      MaxHeight="130" 436.                      Margin="20,5,20,0"> 437.                    <Border Margin="0" 438.                            BorderThickness="1" 439.                            BorderBrush="{StaticResource GenericShallowBorderBrush}" 440.                            Visibility="{Binding ElementName=ResourcesScrollViewer, Path=ComputedVerticalScrollBarVisibility}"></Border> 441.                    <ScrollViewer x:Name="ResourcesScrollViewer" 442.                                  IsTabStop="false" 443.                                  Grid.Row="6" 444.                                  Grid.Column="0" 445.                                  Grid.ColumnSpan="2" 446.                                  Margin="1" 447.                                  telerik:StyleManager.Theme="{StaticResource Theme}" 448.                                  VerticalScrollBarVisibility="Auto"> 449.                        <scheduler:ResourcesItemsControl x:Name="PART_Resources" 450.                                                         HorizontalAlignment="Left" 451.                                                         Padding="0,2,0,5" 452.                                                         IsTabStop="false" 453.                                                         ItemsSource="{TemplateBinding ResourceTypeModels}" 454.                                                         ItemTemplateSelector="{StaticResource ItemTemplateSelector}" /> 455.                    </ScrollViewer> 456.                </Grid> 457.                <StackPanel x:Name="FooterControls" 458.                            Margin="5 10 10 10" 459.                            Grid.Row="8" 460.                            Grid.Column="1" 461.                            HorizontalAlignment="Left" 462.                            Orientation="Horizontal"> 463.                    <telerik:RadButton x:Name="OKButton" 464.                                       Margin="5" 465.                                       Padding="10 0" 466.                                       MinWidth="80" 467.                                       Command="telerikScheduler:RadSchedulerCommands.SaveAppointment" 468.                                       telerik:StyleManager.Theme="{StaticResource Theme}" 469.                                       telerikNavigation:RadWindow.ResponseButton="Accept" 470.                                       telerik:LocalizationManager.ResourceKey="SaveAndCloseCommandText"> 471.                    </telerik:RadButton> 472.                    <telerik:RadButton x:Name="CancelButton" 473.                                       Margin="5" 474.                                       Padding="10 0" 475.                                       MinWidth="80" 476.                                       telerik:LocalizationManager.ResourceKey="Cancel" 477.                                       telerik:StyleManager.Theme="{StaticResource Theme}" 478.                                       telerikNavigation:RadWindow.ResponseButton="Cancel" 479.                                       Command="telerik:WindowCommands.Close"> 480.                    </telerik:RadButton> 481.                </StackPanel> 482.            </Grid> 483.            <vsm:VisualStateManager.VisualStateGroups> 484.                <vsm:VisualStateGroup x:Name="RecurrenceRuleState"> 485.                    <vsm:VisualState x:Name="RecurrenceRuleIsNull"> 486.                        <Storyboard> 487.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="StartDateTime" 488.                                                           Storyboard.TargetProperty="IsEnabled" 489.                                                           Duration="0"> 490.                                <DiscreteObjectKeyFrame KeyTime="0" 491.                                                        Value="True" /> 492.                            </ObjectAnimationUsingKeyFrames> 493.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="EndDateTime" 494.                                                           Storyboard.TargetProperty="IsEnabled" 495.                                                           Duration="0"> 496.                                <DiscreteObjectKeyFrame KeyTime="0" 497.                                                        Value="True" /> 498.                            </ObjectAnimationUsingKeyFrames> 499.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="AllDayEventCheckbox" 500.                                                           Storyboard.TargetProperty="IsEnabled" 501.                                                           Duration="0"> 502.                                <DiscreteObjectKeyFrame KeyTime="0" 503.                                                        Value="True" /> 504.                            </ObjectAnimationUsingKeyFrames> 505.                        </Storyboard> 506.                    </vsm:VisualState> 507.                    <vsm:VisualState x:Name="RecurrenceRuleIsNotNull"> 508.                        <Storyboard> 509.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="StartDateTime" 510.                                                           Storyboard.TargetProperty="IsEnabled" 511.                                                           Duration="0"> 512.                                <DiscreteObjectKeyFrame KeyTime="0" 513.                                                        Value="False" /> 514.                            </ObjectAnimationUsingKeyFrames> 515.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="EndDateTime" 516.                                                           Storyboard.TargetProperty="IsEnabled" 517.                                                           Duration="0"> 518.                                <DiscreteObjectKeyFrame KeyTime="0" 519.                                                        Value="False" /> 520.                            </ObjectAnimationUsingKeyFrames> 521.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="AllDayEventCheckbox" 522.                                                           Storyboard.TargetProperty="IsEnabled" 523.                                                           Duration="0"> 524.                                <DiscreteObjectKeyFrame KeyTime="0" 525.                                                        Value="False" /> 526.                            </ObjectAnimationUsingKeyFrames> 527.                        </Storyboard> 528.                    </vsm:VisualState> 529.                </vsm:VisualStateGroup> 530.            </vsm:VisualStateManager.VisualStateGroups> 531.        </StackPanel> 532.    </ControlTemplate> 533.    <DataTemplate x:Key="AppointmentDialogWindowHeaderDataTemplate"> 534.        <StackPanel Orientation="Horizontal" 535.                    MaxWidth="400"> 536.            <TextBlock telerik:LocalizationManager.ResourceKey="Event" 537.                       Visibility="{Binding Appointment.IsAllDayEvent, Converter={StaticResource BooleanToVisibilityConverter}}" /> 538.            <TextBlock telerik:LocalizationManager.ResourceKey="Appointment" 539.                       Visibility="{Binding Appointment.IsAllDayEvent, Converter={StaticResource InvertedBooleanToVisibilityConverter}}" /> 540.            <TextBlock Text=" - " /> 541.            <TextBlock x:Name="SubjectTextBlock" 542.                       Visibility="{Binding Appointment.Subject, Converter={StaticResource NullToVisibilityConverter}}" 543.                       Text="{Binding Appointment.Subject}" /> 544.            <TextBlock telerik:LocalizationManager.ResourceKey="Untitled" 545.                       Visibility="{Binding Appointment.Subject, Converter={StaticResource InvertedNullToVisibilityConverter}}" /> 546.        </StackPanel> 547.    </DataTemplate> 548.    <Style x:Key="EditAppointmentStyle" 549.           TargetType="telerikScheduler:AppointmentDialogWindow"> 550.        <Setter Property="IconTemplate" 551.                Value="{StaticResource IconDataEditTemplate}" /> 552.        <Setter Property="HeaderTemplate" 553.                Value="{StaticResource AppointmentDialogWindowHeaderDataTemplate}" /> 554.        <Setter Property="Background" 555.                Value="{StaticResource DialogWindowBackground}" /> 556.        <Setter Property="Template" 557.                Value="{StaticResource EditAppointmentTemplate}" /> 558.    </Style> 559.</UserControl.Resources> The first line there is the DataContextProxy I mentioned previously- we use that again to work a bit of magic in this template. Where we start getting into the dialog in question is line 132, but line 407 is where things start getting interesting.  The ItemsSource is pointing at a list that exists in my ViewModel (or code-behind, if it is used as a DataContext), the SelectedValue is the item I am actually binding from the applicant (note the TwoWay binding), and SelectedValuePath and DisplayMemberPath ensure the proper applicant is being displayed from the collection.  You will also see similar starting on line 420 where I do the same for the Jobs we'll be displaying. Just to wrap-up the Xaml, here's the RadScheduler declaraction that ties this all together and will be the main focus of our view: 01.<telerikScheduler:RadScheduler x:Name="xJobsScheduler" 02.                  Grid.Row="1" 03.                  Grid.Column="1" 04.                  Width="800" 05.                  MinWidth="600" 06.                  Height="500" 07.                  MinHeight="300" 08.                  AppointmentsSource="{Binding Interviews}" 09.                  EditAppointmentStyle="{StaticResource EditAppointmentStyle}" 10.                  command:AppointmentAddedEventClass.Command="{Binding AddAppointmentCommand}" 11.                  command:ApptCreatedEventClass.Command="{Binding ApptCreatingCommand}" 12.                  command:ApptEditedEventClass.Command="{Binding ApptEditedCommand}" 13.                  command:ApptDeletedEventClass.Command="{Binding ApptDeletedCommand}"> 14.</telerikScheduler:RadScheduler> Now, we get to the ViewModel and what it takes to get that rigged up.  And for those of you who remember the jobs post, those command:s in the Xaml are pointing to attached behavior commands that reproduce the respective events.  This becomes very handy when we're setting up the code-behind version. ;) ViewModel I've been liking this approach so far, so I'm going to put the entire ViewModel here and then go into the lines of interest.  Of course, feel free to ask me questions about anything that isn't clear (by line number, ideally) so I can help out if I have missed anything important: 001.public class SchedulerViewModel : ViewModelBase 002.{ 003.    private readonly IEventAggregator eventAggregator; 004.    private readonly IRegionManager regionManager; 005.   006.    public RecruitingContext context; 007.   008.    private ObservableItemCollection<InterviewAppointment> _interviews = new ObservableItemCollection<InterviewAppointment>(); 009.    public ObservableItemCollection<InterviewAppointment> Interviews 010.    { 011.        get { return _interviews; } 012.        set 013.        { 014.            if (_interviews != value) 015.            { 016.                _interviews = value; 017.                NotifyChanged("Interviews"); 018.            } 019.        } 020.    } 021.   022.    private QueryableCollectionView _jobsList; 023.    public QueryableCollectionView JobsList 024.    { 025.        get { return this._jobsList; } 026.        set 027.        { 028.            if (this._jobsList != value) 029.            { 030.                this._jobsList = value; 031.                this.NotifyChanged("JobsList"); 032.            } 033.        } 034.    } 035.   036.    private QueryableCollectionView _applicantList; 037.    public QueryableCollectionView ApplicantList 038.    { 039.        get { return _applicantList; } 040.        set 041.        { 042.            if (_applicantList != value) 043.            { 044.                _applicantList = value; 045.                NotifyChanged("ApplicantList"); 046.            } 047.        } 048.    } 049.   050.    public DelegateCommand<object> AddAppointmentCommand { get; set; } 051.    public DelegateCommand<object> ApptCreatingCommand { get; set; } 052.    public DelegateCommand<object> ApptEditedCommand { get; set; } 053.    public DelegateCommand<object> ApptDeletedCommand { get; set; } 054.   055.    public SchedulerViewModel(IEventAggregator eventAgg, IRegionManager regionmanager) 056.    { 057.        // set Unity items 058.        this.eventAggregator = eventAgg; 059.        this.regionManager = regionmanager; 060.   061.        // load our context 062.        context = new RecruitingContext(); 063.        LoadOperation<Interview> loadOp = context.Load(context.GetInterviewsQuery()); 064.        loadOp.Completed += new EventHandler(loadOp_Completed); 065.   066.        this._jobsList = new QueryableCollectionView(context.JobPostings); 067.        context.Load(context.GetJobPostingsQuery()); 068.   069.        this._applicantList = new QueryableCollectionView(context.Applicants); 070.        context.Load(context.GetApplicantsQuery()); 071.   072.        AddAppointmentCommand = new DelegateCommand<object>(this.AddAppt); 073.        ApptCreatingCommand = new DelegateCommand<object>(this.ApptCreating); 074.        ApptEditedCommand = new DelegateCommand<object>(this.ApptEdited); 075.        ApptDeletedCommand = new DelegateCommand<object>(this.ApptDeleted); 076.   077.    } 078.   079.    void loadOp_Completed(object sender, EventArgs e) 080.    { 081.        LoadOperation loadop = sender as LoadOperation; 082.   083.        foreach (var ent in loadop.Entities) 084.        { 085.            _interviews.Add(EntityToAppointment(ent as Interview)); 086.        } 087.    } 088.   089.    #region Appointment Adding 090.   091.    public void AddAppt(object obj) 092.    { 093.        // now we have a new InterviewAppointment to add to our QCV :) 094.        InterviewAppointment newInterview = obj as InterviewAppointment; 095.   096.        this.context.Interviews.Add(AppointmentToEntity(newInterview)); 097.        this.context.SubmitChanges((s) => 098.        { 099.            ActionHistory myAction = new ActionHistory(); 100.            myAction.InterviewID = newInterview.InterviewID; 101.            myAction.PostingID = newInterview.PostingID; 102.            myAction.ApplicantID = newInterview.ApplicantID; 103.            myAction.Description = String.Format("Interview with {0} has been created by {1}", newInterview.ApplicantID.ToString(), "default user"); 104.            myAction.TimeStamp = DateTime.Now; 105.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 106.        } 107.            , null); 108.    } 109.   110.    public void ApptCreating(object obj) 111.    { 112.        // handled in the behavior, just a placeholder to ensure it runs :) 113.    } 114.   115.    #endregion 116.   117.    #region Appointment Editing 118.   119.    public void ApptEdited(object obj) 120.    { 121.        Interview editedInterview = (from x in context.Interviews 122.                            where x.InterviewID == (obj as InterviewAppointment).InterviewID 123.                            select x).SingleOrDefault(); 124.   125.        CopyAppointmentEdit(editedInterview, obj as InterviewAppointment); 126.   127.        context.SubmitChanges((s) => { 128.            ActionHistory myAction = new ActionHistory(); 129.            myAction.InterviewID = editedInterview.InterviewID; 130.            myAction.PostingID = editedInterview.PostingID; 131.            myAction.ApplicantID = editedInterview.ApplicantID; 132.            myAction.Description = String.Format("Interview with {0} has been modified by {1}", editedInterview.ApplicantID.ToString(), "default user"); 133.            myAction.TimeStamp = DateTime.Now; 134.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); } 135.            , null); 136.    } 137.   138.    #endregion 139.   140.    #region Appointment Deleting 141.   142.    public void ApptDeleted(object obj) 143.    { 144.        Interview deletedInterview = (from x in context.Interviews 145.                                      where x.InterviewID == (obj as InterviewAppointment).InterviewID 146.                                      select x).SingleOrDefault(); 147.   148.        context.Interviews.Remove(deletedInterview); 149.        context.SubmitChanges((s) => 150.        { 151.            ActionHistory myAction = new ActionHistory(); 152.            myAction.InterviewID = deletedInterview.InterviewID; 153.            myAction.PostingID = deletedInterview.PostingID; 154.            myAction.ApplicantID = deletedInterview.ApplicantID; 155.            myAction.Description = String.Format("Interview with {0} has been deleted by {1}", deletedInterview.ApplicantID.ToString(), "default user"); 156.            myAction.TimeStamp = DateTime.Now; 157.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 158.        } 159.            , null); 160.    } 161.   162.    #endregion 163.   164.    #region Appointment Helpers :) 165.   166.    public Interview AppointmentToEntity(InterviewAppointment ia) 167.    { 168.        Interview newInterview = new Interview(); 169.        newInterview.Subject = ia.Subject; 170.        newInterview.Body = ia.Body; 171.        newInterview.Start = ia.Start; 172.        newInterview.End = ia.End; 173.        newInterview.ApplicantID = ia.ApplicantID; 174.        newInterview.PostingID = ia.PostingID; 175.        newInterview.InterviewID = ia.InterviewID; 176.   177.        return newInterview; 178.    } 179.   180.    public InterviewAppointment EntityToAppointment(Interview ia) 181.    { 182.        InterviewAppointment newInterview = new InterviewAppointment(); 183.        newInterview.Subject = ia.Subject; 184.        newInterview.Body = ia.Body; 185.        newInterview.Start = ia.Start; 186.        newInterview.End = ia.End; 187.        newInterview.ApplicantID = ia.ApplicantID; 188.        newInterview.PostingID = ia.PostingID; 189.        newInterview.InterviewID = ia.InterviewID; 190.   191.        return newInterview; 192.    } 193.   194.    public void CopyAppointmentEdit(Interview entityInterview, InterviewAppointment appointmentInterview) 195.    { 196.        entityInterview.Subject = appointmentInterview.Subject; 197.        entityInterview.Body = appointmentInterview.Body; 198.        entityInterview.Start = appointmentInterview.Start; 199.        entityInterview.End = appointmentInterview.End; 200.        entityInterview.ApplicantID = appointmentInterview.ApplicantID; 201.        entityInterview.PostingID = appointmentInterview.PostingID; 202.    } 203.   204.    #endregion 205.} One thing we're doing here which you won't see in any of the other ViewModels is creating a duplicate collection.  I know this is something which will be fixed down the line for using RadScheduler, simplifying this process, but with WCF RIA changing as it does I wanted to ensure functionality would remain consistent as I continued development on this application.  So, I do a little bit of duplication, but for the greater good.  This all takes place starting on line 79, so for every entity that comes back we add it to the collection that is bound to RadScheduler.  Otherwise, the DelegateCommands that you see correspond directly to the events they are named after.  In each case, rather than sending over the full event arguments, I just send in the appointment in question (coming through as the object obj in all cases) so I can add (line 91), edit (line 119), and delete appointments (line 142) like normal.  This just ensures they get updated back to my database.  Also, the one bit of code you won't see is for the Appointment Creating (line 110) event- that is because in the command I've created I simply make the replacement I need to: 1.void element_AppointmentCreating(object sender, AppointmentCreatingEventArgs e) 2.{ 3.    e.NewAppointment = new InterviewAppointment(); 4.    base.ExecuteCommand(); 5.} And the ViewModel is none the wiser, the appointments just work as far as it is concerned since as they are created they become InterviewAppointments.  End result?  I've customized my EditAppointmentDialog as follows: And adding, editing, and deleting appointments works like a charm.  I can even 'edit' by moving appointments around RadScheduler, so as they are dropped into a timeslot they perform their full edit routine and things get updated. And then, the Code-Behind Version Perhaps the thing I like the most about doing one then the other is I get to steal 90% or more of the code from the MVVM version.  For example, the only real changes to the Code-Behind Xaml file exist in the control declaration, in which I use events instead of attached-behavior-event-commands: 01.<telerikScheduler:RadScheduler x:Name="xJobsScheduler" 02.                  Grid.Row="1" 03.                  Grid.Column="1" 04.                  Width="800" 05.                  MinWidth="600" 06.                  Height="500" 07.                  MinHeight="300" 08.                  EditAppointmentStyle="{StaticResource EditAppointmentStyle}" 09.                  AppointmentAdded="xJobsScheduler_AppointmentAdded" 10.                  AppointmentCreating="xJobsScheduler_AppointmentCreating" 11.                  AppointmentEdited="xJobsScheduler_AppointmentEdited" 12.                  AppointmentDeleted="xJobsScheduler_AppointmentDeleted"> 13.</telerikScheduler:RadScheduler> Easy, right?  Otherwise, all the same styling in UserControl.Resources was re-used, right down to the DataContextProxy that lets us bind to a collection from our viewmodel (in this case, our code-behind) to use within the DataTemplate.  The code conversion gets even easier, as I could literally copy and paste almost everything from the ViewModel to my Code-Behind, just a matter of pasting the right section into the right event.  Here's the code-behind as proof: 001.public partial class SchedulingView : UserControl, INotifyPropertyChanged 002.{ 003.    public RecruitingContext context; 004.   005.    private QueryableCollectionView _jobsList; 006.    public QueryableCollectionView JobsList 007.    { 008.        get { return this._jobsList; } 009.        set 010.        { 011.            if (this._jobsList != value) 012.            { 013.                this._jobsList = value; 014.                this.NotifyChanged("JobsList"); 015.            } 016.        } 017.    } 018.   019.    private QueryableCollectionView _applicantList; 020.    public QueryableCollectionView ApplicantList 021.    { 022.        get { return _applicantList; } 023.        set 024.        { 025.            if (_applicantList != value) 026.            { 027.                _applicantList = value; 028.                NotifyChanged("ApplicantList"); 029.            } 030.        } 031.    } 032.   033.    private ObservableItemCollection<InterviewAppointment> _interviews = new ObservableItemCollection<InterviewAppointment>(); 034.    public ObservableItemCollection<InterviewAppointment> Interviews 035.    { 036.        get { return _interviews; } 037.        set 038.        { 039.            if (_interviews != value) 040.            { 041.                _interviews = value; 042.                NotifyChanged("Interviews"); 043.            } 044.        } 045.    } 046.   047.    public SchedulingView() 048.    { 049.        InitializeComponent(); 050.   051.        this.DataContext = this; 052.   053.        this.Loaded += new RoutedEventHandler(SchedulingView_Loaded); 054.    } 055.   056.    void SchedulingView_Loaded(object sender, RoutedEventArgs e) 057.    { 058.        this.xJobsScheduler.AppointmentsSource = Interviews; 059.   060.        context = new RecruitingContext(); 061.           062.        LoadOperation loadop = context.Load(context.GetInterviewsQuery()); 063.        loadop.Completed += new EventHandler(loadop_Completed); 064.   065.        this._applicantList = new QueryableCollectionView(context.Applicants); 066.        context.Load(context.GetApplicantsQuery()); 067.   068.        this._jobsList = new QueryableCollectionView(context.JobPostings); 069.        context.Load(context.GetJobPostingsQuery()); 070.    } 071.   072.    void loadop_Completed(object sender, EventArgs e) 073.    { 074.        LoadOperation loadop = sender as LoadOperation; 075.   076.        _interviews.Clear(); 077.   078.        foreach (var ent in loadop.Entities) 079.        { 080.            _interviews.Add(EntityToAppointment(ent as Interview)); 081.        } 082.    } 083.   084.    private void xJobsScheduler_AppointmentAdded(object sender, Telerik.Windows.Controls.AppointmentAddedEventArgs e) 085.    { 086.        // now we have a new InterviewAppointment to add to our QCV :) 087.        InterviewAppointment newInterview = e.Appointment as InterviewAppointment; 088.   089.        this.context.Interviews.Add(AppointmentToEntity(newInterview)); 090.        this.context.SubmitChanges((s) => 091.        { 092.            ActionHistory myAction = new ActionHistory(); 093.            myAction.InterviewID = newInterview.InterviewID; 094.            myAction.PostingID = newInterview.PostingID; 095.            myAction.ApplicantID = newInterview.ApplicantID; 096.            myAction.Description = String.Format("Interview with {0} has been created by {1}", newInterview.ApplicantID.ToString(), "default user"); 097.            myAction.TimeStamp = DateTime.Now; 098.            context.ActionHistories.Add(myAction); 099.            context.SubmitChanges(); 100.        } 101.            , null); 102.    } 103.   104.    private void xJobsScheduler_AppointmentCreating(object sender, Telerik.Windows.Controls.AppointmentCreatingEventArgs e) 105.    { 106.        e.NewAppointment = new InterviewAppointment(); 107.    } 108.   109.    private void xJobsScheduler_AppointmentEdited(object sender, Telerik.Windows.Controls.AppointmentEditedEventArgs e) 110.    { 111.        Interview editedInterview = (from x in context.Interviews 112.                                     where x.InterviewID == (e.Appointment as InterviewAppointment).InterviewID 113.                                     select x).SingleOrDefault(); 114.   115.        CopyAppointmentEdit(editedInterview, e.Appointment as InterviewAppointment); 116.   117.        context.SubmitChanges((s) => 118.        { 119.            ActionHistory myAction = new ActionHistory(); 120.            myAction.InterviewID = editedInterview.InterviewID; 121.            myAction.PostingID = editedInterview.PostingID; 122.            myAction.ApplicantID = editedInterview.ApplicantID; 123.            myAction.Description = String.Format("Interview with {0} has been modified by {1}", editedInterview.ApplicantID.ToString(), "default user"); 124.            myAction.TimeStamp = DateTime.Now; 125.            context.ActionHistories.Add(myAction); 126.            context.SubmitChanges(); 127.        } 128.            , null); 129.    } 130.   131.    private void xJobsScheduler_AppointmentDeleted(object sender, Telerik.Windows.Controls.AppointmentDeletedEventArgs e) 132.    { 133.        Interview deletedInterview = (from x in context.Interviews 134.                                      where x.InterviewID == (e.Appointment as InterviewAppointment).InterviewID 135.                                      select x).SingleOrDefault(); 136.   137.        context.Interviews.Remove(deletedInterview); 138.        context.SubmitChanges((s) => 139.        { 140.            ActionHistory myAction = new ActionHistory(); 141.            myAction.InterviewID = deletedInterview.InterviewID; 142.            myAction.PostingID = deletedInterview.PostingID; 143.            myAction.ApplicantID = deletedInterview.ApplicantID; 144.            myAction.Description = String.Format("Interview with {0} has been deleted by {1}", deletedInterview.ApplicantID.ToString(), "default user"); 145.            myAction.TimeStamp = DateTime.Now; 146.            context.ActionHistories.Add(myAction); 147.            context.SubmitChanges(); 148.        } 149.            , null); 150.    } 151.   152.    #region Appointment Helpers :) 153.   154.    public Interview AppointmentToEntity(InterviewAppointment ia) 155.    { 156.        Interview newInterview = new Interview(); 157.        newInterview.Subject = ia.Subject; 158.        newInterview.Body = ia.Body; 159.        newInterview.Start = ia.Start; 160.        newInterview.End = ia.End; 161.        newInterview.ApplicantID = ia.ApplicantID; 162.        newInterview.PostingID = ia.PostingID; 163.        newInterview.InterviewID = ia.InterviewID; 164.   165.        return newInterview; 166.    } 167.   168.    public InterviewAppointment EntityToAppointment(Interview ia) 169.    { 170.        InterviewAppointment newInterview = new InterviewAppointment(); 171.        newInterview.Subject = ia.Subject; 172.        newInterview.Body = ia.Body; 173.        newInterview.Start = ia.Start; 174.        newInterview.End = ia.End; 175.        newInterview.ApplicantID = ia.ApplicantID; 176.        newInterview.PostingID = ia.PostingID; 177.        newInterview.InterviewID = ia.InterviewID; 178.   179.        return newInterview; 180.    } 181.   182.    public void CopyAppointmentEdit(Interview entityInterview, InterviewAppointment appointmentInterview) 183.    { 184.        entityInterview.Subject = appointmentInterview.Subject; 185.        entityInterview.Body = appointmentInterview.Body; 186.        entityInterview.Start = appointmentInterview.Start; 187.        entityInterview.End = appointmentInterview.End; 188.        entityInterview.ApplicantID = appointmentInterview.ApplicantID; 189.        entityInterview.PostingID = appointmentInterview.PostingID; 190.    } 191.   192.    #endregion 193.   194.    #region INotifyPropertyChanged Members 195.   196.    public event PropertyChangedEventHandler PropertyChanged; 197.   198.    public void NotifyChanged(string propertyName) 199.    { 200.        if (string.IsNullOrEmpty(propertyName)) 201.            throw new ArgumentException("propertyName"); 202.   203.        PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 204.    } 205.   206.    #endregion 207.} Nice... right? :) One really important thing to note as well.  See on line 51 where I set the DataContext before the Loaded event?  This is super important, as if you don't have this set before the usercontrol is loaded, the DataContextProxy has no context to use and your EditAppointmentDialog Job/Applicant dropdowns will be blank and empty.  Trust me on this, took a little bit of debugging to figure out that by setting the DataContext post-loaded would only lead to disaster and frustration.  Otherwise, the only other real difference is that instead of sending an ActionHistory item through an event to get added to the database and saved, I do those right in the callback from submitting.  The Result Again, I only have to post one picture because these bad boys used nearly identical code for both the MVVM and the code-behind views, so our end result is... So what have we learned here today?  One, for the most part this MVVM thing is somewhat easy.  Yeah, you sometimes have to write a bunch of extra code, but with the help of a few useful snippits you can turn the process into a pretty streamlined little workflow.  Heck, this story gets even easier as you can see in this blog post by Michael Washington- specifically run a find on 'InvokeCommandAction' and you'll see the section regarding the command on TreeView in Blend 4.  Brilliant!  MVVM never looked so sweet! Otherwise, it is business as usual with RadScheduler for Silverlight whichever path you're choosing for your development.  Between now and the next post, I'll be cleaning up styles a bit (those RadComboBoxes are a little too close to my labels!) and adding some to the RowDetailsViews for Applicants and Jobs, so you can see all the info for an appointment in the dropdown tab view.  Otherwise, we're about ready to call a wrap on this oneDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Silverlight Recruiting Application Part 6 - Adding an Interview Scheduling Module/View

  Between the last post and this one I went ahead and carried the ideas for the Jobs module and view into the Applicants module and view- they're both doing more or less the same thing, except with different objects being at their core.  Made for an easy cut-and-paste operation with a few items being switched from one to another.  Now that we have the ability to add postings and applicants, wouldn't it be nice if we could schedule an interview?  Of course it would! Scheduling Module I think you get the drift from previous posts that these project structures start looking somewhat similar.  The interview scheduling module is no different than the rest- it gets a SchedulingModule.cs file at the root that inherits from IModule, and there is a single SchedulerView.xsml and SchedulerViewModel.cs setup for our V+VM.  We have one unique concern as we enter into this- RadScheduler deals with AppointmentsSource, not ItemsSource, so there are some special considerations to take into account when planning this module. First, I need something which inherits from AppointmentBase.  This is the core of the RadScheduler appointment, and if you are planning to do any form of custom appointment, you'll want it to inherit from this.  Then you can add-on functionality as needed.  Here is my addition to the mix, the InterviewAppointment: 01.public class InterviewAppointment : AppointmentBase 02.{ 03.    private int _applicantID; 04.    public int ApplicantID 05.    { 06.        get { return this._applicantID; } 07.        set 08.        { 09.            if (_applicantID != value) 10.            { 11.                _applicantID = value; 12.                OnPropertyChanged("ApplicantID"); 13.            } 14.        } 15.    } 16.   17.    private int _postingID; 18.    public int PostingID 19.    { 20.        get { return _postingID; } 21.        set 22.        { 23.            if (_postingID != value) 24.            { 25.                _postingID = value; 26.                OnPropertyChanged("PostingID"); 27.            } 28.        } 29.    } 30.   31.    private string _body; 32.    public string Body 33.    { 34.        get { return _body; } 35.        set 36.        { 37.            if (_body != value) 38.            { 39.                _body = value; 40.                OnPropertyChanged("Body"); 41.            } 42.        } 43.    } 44.   45.    private int _interviewID; 46.    public int InterviewID 47.    { 48.        get { return _interviewID; } 49.        set 50.        { 51.            if (_interviewID != value) 52.            { 53.                _interviewID = value; 54.                OnPropertyChanged("InterviewID"); 55.            } 56.        } 57.    } 58.   59.    public override IAppointment Copy() 60.    { 61.        IAppointment appointment = new InterviewAppointment(); 62.        appointment.CopyFrom(this);             63.        return appointment; 64.    } 65.   66.    public override void CopyFrom(IAppointment other) 67.    {             68.        base.CopyFrom(other); 69.        var appointment = other as InterviewAppointment; 70.        if (appointment != null) 71.        { 72.            ApplicantID = appointment.ApplicantID; 73.            PostingID = appointment.PostingID; 74.            Body = appointment.Body; 75.            InterviewID = appointment.InterviewID; 76.        } 77.    } 78.} Nothing too exciting going on here, we just make sure that our custom fields are persisted (specifically set in CopyFrom at the bottom) and notifications are fired- otherwise this ends up exactly like the standard appointment as far as interactions, etc.  But if we've got custom appointment items... that also means we need to customize what our appointment dialog window will look like. Customizing the Edit Appointment Dialog This initially sounds a lot more intimidating than it really is.  The first step here depends on what you're dealing with for theming, but for ease of everything I went ahead and extracted my templates in Blend for RadScheduler so I could modify it as I pleased.  For the faint of heart, the RadScheduler template is a few thousand lines of goodness since there are some very complex things going on in that control.  I've gone ahead and trimmed down the template parts I don't need as much as possible, so what is left is all that is relevant to the Edit Appointment Dialog.  Here's the resulting Xaml, with line numbers, so I can explain further: 001.<UserControl.Resources> 002.    <!-- begin Necessary Windows 7 Theme Resources for EditAppointmentTemplate --> 003.    <helpers:DataContextProxy x:Key="DataContextProxy" /> 004.       005.    <telerik:Windows7Theme x:Key="Theme" /> 006.    <SolidColorBrush x:Key="DialogWindowBackground" 007.                     Color="White" /> 008.    <SolidColorBrush x:Key="CategorySelectorBorderBrush" 009.                     Color="#FFB1B1B1" /> 010.    <LinearGradientBrush x:Key="RadToolBar_InnerBackground" 011.                         EndPoint="0.5,1" 012.                         StartPoint="0.5,0"> 013.        <GradientStop Color="#FFFDFEFF" 014.                      Offset="0" /> 015.        <GradientStop Color="#FFDDE9F7" 016.                      Offset="1" /> 017.        <GradientStop Color="#FFE6F0FA" 018.                      Offset="0.5" /> 019.        <GradientStop Color="#FFDCE6F4" 020.                      Offset="0.5" /> 021.    </LinearGradientBrush> 022.    <Style x:Key="FormElementTextBlockStyle" 023.           TargetType="TextBlock"> 024.        <Setter Property="HorizontalAlignment" 025.                Value="Right" /> 026.        <Setter Property="VerticalAlignment" 027.                Value="Top" /> 028.        <Setter Property="Margin" 029.                Value="15, 15, 0, 2" /> 030.    </Style> 031.    <Style x:Key="FormElementStyle" 032.           TargetType="FrameworkElement"> 033.        <Setter Property="Margin" 034.                Value="10, 10, 0, 2" /> 035.    </Style> 036.    <SolidColorBrush x:Key="GenericShallowBorderBrush" 037.                     Color="#FF979994" /> 038.    <telerik:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" /> 039.    <telerikScheduler:ImportanceToBooleanConverter x:Key="ImportanceToBooleanConverter" /> 040.    <telerikScheduler:NullToVisibilityConverter x:Key="NullToVisibilityConverter" /> 041.    <telerikScheduler:InvertedNullToVisibilityConverter x:Key="InvertedNullToVisibilityConverter" /> 042.    <scheduler:ResourcesSeparatorConverter x:Key="ResourcesSeparatorConverter" /> 043.    <DataTemplate x:Key="IconDataEditTemplate"> 044.        <Image Source="/Telerik.Windows.Controls.Scheduler;component/Themes/Office/Images/cal.png" 045.               Margin="3,3,0,0" 046.               Width="16" 047.               Height="16" /> 048.    </DataTemplate> 049.    <DataTemplate x:Key="SingleSelectionTemplate"> 050.        <Grid VerticalAlignment="Stretch" 051.              HorizontalAlignment="Stretch"> 052.            <Grid.RowDefinitions> 053.                <RowDefinition Height="Auto" /> 054.            </Grid.RowDefinitions> 055.            <Grid.ColumnDefinitions> 056.                <ColumnDefinition Width="Auto" 057.                                  MinWidth="84" /> 058.                <ColumnDefinition Width="Auto" 059.                                  MinWidth="200" /> 060.            </Grid.ColumnDefinitions> 061.            <TextBlock x:Name="SelectionNameLabel" 062.                       Margin="0,13,4,2" 063.                       Text="{Binding ResourceType.DisplayName}" 064.                       Style="{StaticResource FormElementTextBlockStyle}" 065.                       Grid.Column="0" /> 066.            <telerikInput:RadComboBox ItemsSource="{Binding ResourceItems}" 067.                                      Width="185" 068.                                      Margin="5,10,20,2" 069.                                      HorizontalAlignment="Left" 070.                                      Grid.Column="1" 071.                                      ClearSelectionButtonVisibility="Visible" 072.                                      ClearSelectionButtonContent="Clear All" 073.                                      DisplayMemberPath="Resource.DisplayName" 074.                                      telerik:StyleManager.Theme="{StaticResource Theme}" 075.                                      SelectedItem="{Binding SelectedItem, Mode=TwoWay}" /> 076.        </Grid> 077.    </DataTemplate> 078.    <DataTemplate x:Key="MultipleSelectionTemplate"> 079.        <Grid VerticalAlignment="Stretch" 080.              HorizontalAlignment="Stretch"> 081.            <Grid.RowDefinitions> 082.                <RowDefinition Height="Auto" /> 083.            </Grid.RowDefinitions> 084.            <Grid.ColumnDefinitions> 085.                <ColumnDefinition Width="Auto" 086.                                  MinWidth="84" /> 087.                <ColumnDefinition Width="Auto" 088.                                  MinWidth="200" /> 089.            </Grid.ColumnDefinitions> 090.            <TextBlock x:Name="SelectionNameLabel" 091.                       Grid.Column="0" 092.                       Text="{Binding ResourceType.DisplayName}" 093.                       Margin="0,13,4,2" 094.                       Style="{StaticResource FormElementTextBlockStyle}" /> 095.            <telerikInput:RadComboBox Grid.Column="1" 096.                                      Width="185" 097.                                      HorizontalAlignment="Left" 098.                                      Margin="5,10,20,2" 099.                                      ItemsSource="{Binding ResourceItems}" 100.                                      SelectedIndex="{Binding SelectedIndex, Mode=TwoWay}" 101.                                      ClearSelectionButtonVisibility="Visible" 102.                                      ClearSelectionButtonContent="Clear All" 103.                                      telerik:StyleManager.Theme="{StaticResource Theme}"> 104.                <telerikInput:RadComboBox.ItemTemplate> 105.                    <DataTemplate> 106.                        <Grid HorizontalAlignment="Stretch" 107.                              VerticalAlignment="Stretch"> 108.                            <CheckBox VerticalAlignment="Center" 109.                                      HorizontalContentAlignment="Stretch" 110.                                      VerticalContentAlignment="Center" 111.                                      IsChecked="{Binding IsChecked, Mode=TwoWay}" 112.                                      Content="{Binding Resource.DisplayName}"> 113.                                <CheckBox.ContentTemplate> 114.                                    <DataTemplate> 115.                                        <TextBlock HorizontalAlignment="Stretch" 116.                                                   VerticalAlignment="Stretch" 117.                                                   Text="{Binding Content, RelativeSource={RelativeSource TemplatedParent}}" /> 118.                                    </DataTemplate> 119.                                </CheckBox.ContentTemplate> 120.                            </CheckBox> 121.                        </Grid> 122.                    </DataTemplate> 123.                </telerikInput:RadComboBox.ItemTemplate> 124.            </telerikInput:RadComboBox> 125.        </Grid> 126.    </DataTemplate> 127.    <scheduler:ResourceTypeTemplateSelector x:Key="ItemTemplateSelector" 128.                                            MultipleSelectionTemplate="{StaticResource MultipleSelectionTemplate}" 129.                                            SingleSelectionTemplate="{StaticResource SingleSelectionTemplate}" /> 130.    <!-- end Necessary Windows 7 Theme Resources for EditAppointmentTemplate -->  131.       132.    <ControlTemplate x:Key="EditAppointmentTemplate" 133.                     TargetType="telerikScheduler:AppointmentDialogWindow"> 134.        <StackPanel Background="{TemplateBinding Background}" 135.                    UseLayoutRounding="True"> 136.            <StackPanel Grid.Row="0" 137.                        Orientation="Horizontal" 138.                        Background="{StaticResource RadToolBar_InnerBackground}" 139.                        Grid.ColumnSpan="2" 140.                        Height="0"> 141.                <!-- Recurrence buttons --> 142.                <Border Margin="1,1,0,0" 143.                        Background="#50000000" 144.                        HorizontalAlignment="Left" 145.                        VerticalAlignment="Center" 146.                        Width="2" 147.                        Height="16"> 148.                    <Border Margin="0,0,1,1" 149.                            Background="#80FFFFFF" 150.                            HorizontalAlignment="Left" 151.                            Width="1" /> 152.                </Border> 153.                <Border Margin="1,1,0,0" 154.                        Background="#50000000" 155.                        HorizontalAlignment="Left" 156.                        VerticalAlignment="Center" 157.                        Width="2" 158.                        Height="16"> 159.                    <Border Margin="0,0,1,1" 160.                            Background="#80FFFFFF" 161.                            HorizontalAlignment="Left" 162.                            Width="1" /> 163.                </Border> 164.                <TextBlock telerik:LocalizationManager.ResourceKey="ShowAs" 165.                           VerticalAlignment="Center" 166.                           Margin="5,0,0,0" /> 167.                <telerikInput:RadComboBox ItemsSource="{TemplateBinding TimeMarkers}" 168.                                          Width="100" 169.                                          Height="20" 170.                                          VerticalAlignment="Center" 171.                                          Margin="5,0,0,0" 172.                                          ClearSelectionButtonVisibility="Visible" 173.                                          ClearSelectionButtonContent="Clear" 174.                                          SelectedItem="{Binding TimeMarker,RelativeSource={RelativeSource TemplatedParent},Mode=TwoWay}" 175.                                          telerik:StyleManager.Theme="{StaticResource Theme}"> 176.                    <telerikInput:RadComboBox.ItemTemplate> 177.                        <DataTemplate> 178.                            <StackPanel Orientation="Horizontal"> 179.                                <Rectangle Fill="{Binding TimeMarkerBrush}" 180.                                           Margin="2" 181.                                           Width="12" 182.                                           Height="12" /> 183.                                <TextBlock Text="{Binding TimeMarkerName}" 184.                                           Margin="2" /> 185.                            </StackPanel> 186.                        </DataTemplate> 187.                    </telerikInput:RadComboBox.ItemTemplate> 188.                </telerikInput:RadComboBox> 189.                <telerik:RadToggleButton x:Name="High" 190.                                         BorderThickness="0" 191.                                         Background="{StaticResource RadToolBar_InnerBackground}" 192.                                         DataContext="{TemplateBinding EditedAppointment}" 193.                                         telerik:StyleManager.Theme="{StaticResource Theme}" 194.                                         IsChecked="{Binding Importance,Mode=TwoWay, Converter={StaticResource ImportanceToBooleanConverter},ConverterParameter=High}" 195.                                         Margin="2,2,0,2" 196.                                         Width="23" 197.                                         Height="23" 198.                                         HorizontalContentAlignment="Center" 199.                                         ToolTipService.ToolTip="High importance" 200.                                         CommandParameter="High" 201.                                         Command="telerikScheduler:RadSchedulerCommands.SetAppointmentImportance"> 202.                    <StackPanel HorizontalAlignment="Center"> 203.                        <Path Stretch="Fill" 204.                              Height="10" 205.                              HorizontalAlignment="Center" 206.                              VerticalAlignment="Top" 207.                              Width="5.451" 208.                              Data="M200.39647,58.840393 C200.39337,58.336426 201.14566,57.683922 202.56244,57.684292 C204.06589,57.684685 204.73764,58.357765 204.72783,58.992363 C205.04649,61.795574 203.04713,64.181099 202.47388,66.133446 C201.93753,64.154961 199.9471,61.560352 200.39647,58.840393 z"> 209.                            <Path.Fill> 210.                                <LinearGradientBrush EndPoint="1.059,0.375" 211.                                                     StartPoint="-0.457,0.519"> 212.                                    <GradientStop Color="#FFFF0606" 213.                                                  Offset="0.609" /> 214.                                    <GradientStop Color="#FFBF0303" 215.                                                  Offset="0.927" /> 216.                                </LinearGradientBrush> 217.                            </Path.Fill> 218.                        </Path> 219.                        <Ellipse Height="3" 220.                                 HorizontalAlignment="Center" 221.                                 Margin="0,-1,0,0" 222.                                 VerticalAlignment="Top" 223.                                 Width="3"> 224.                            <Ellipse.Fill> 225.                                <RadialGradientBrush> 226.                                    <GradientStop Color="#FFFF0606" 227.                                                  Offset="0" /> 228.                                    <GradientStop Color="#FFBF0303" 229.                                                  Offset="1" /> 230.                                </RadialGradientBrush> 231.                            </Ellipse.Fill> 232.                        </Ellipse> 233.                    </StackPanel> 234.                </telerik:RadToggleButton> 235.                <telerik:RadToggleButton x:Name="Low" 236.                                         HorizontalContentAlignment="Center" 237.                                         BorderThickness="0" 238.                                         Background="{StaticResource RadToolBar_InnerBackground}" 239.                                         DataContext="{TemplateBinding EditedAppointment}" 240.                                         IsChecked="{Binding Importance,Mode=TwoWay, Converter={StaticResource ImportanceToBooleanConverter},ConverterParameter=Low}" 241.                                         Margin="0,2,0,2" 242.                                         Width="23" 243.                                         Height="23" 244.                                         ToolTipService.ToolTip="Low importance" 245.                                         CommandParameter="Low" 246.                                         telerik:StyleManager.Theme="{StaticResource Theme}" 247.                                         Command="telerikScheduler:RadSchedulerCommands.SetAppointmentImportance"> 248.                    <Path Stretch="Fill" 249.                          Height="12" 250.                          HorizontalAlignment="Center" 251.                          VerticalAlignment="Top" 252.                          Width="9" 253.                          Data="M222.40353,60.139881 L226.65768,60.139843 L226.63687,67.240196 L229.15347,67.240196 L224.37816,71.394943 L219.65274,67.240196 L222.37572,67.219345 z" 254.                          Stroke="#FF0365A7"> 255.                        <Path.Fill> 256.                            <LinearGradientBrush EndPoint="1.059,0.375" 257.                                                 StartPoint="-0.457,0.519"> 258.                                <GradientStop Color="#FFBBE4FF" /> 259.                                <GradientStop Color="#FF024572" 260.                                              Offset="0.836" /> 261.                                <GradientStop Color="#FF43ADF4" 262.                                              Offset="0.466" /> 263.                            </LinearGradientBrush> 264.                        </Path.Fill> 265.                    </Path> 266.                </telerik:RadToggleButton> 267.            </StackPanel > 268.            <Border DataContext="{TemplateBinding EditedAppointment}" 269.                    Background="{Binding Category.CategoryBrush}" 270.                    Visibility="{Binding Category,Converter={StaticResource NullToVisibilityConverter}}" 271.                    CornerRadius="3" 272.                    Height="20" 273.                    Margin="5,10,5,0"> 274.                <TextBlock Text="{Binding Category.DisplayName}" 275.                           VerticalAlignment="Center" 276.                           Margin="5,0,0,0" /> 277.            </Border> 278.            <Grid VerticalAlignment="Stretch" 279.                  HorizontalAlignment="Stretch" 280.                  DataContext="{TemplateBinding EditedAppointment}" 281.                  Background="{TemplateBinding Background}"> 282.                <Grid.RowDefinitions> 283.                    <RowDefinition Height="Auto" /> 284.                    <RowDefinition Height="Auto" /> 285.                    <RowDefinition Height="Auto" /> 286.                    <RowDefinition Height="Auto" /> 287.                    <RowDefinition Height="Auto" /> 288.                    <RowDefinition Height="Auto" /> 289.                    <RowDefinition Height="Auto" /> 290.                    <RowDefinition Height="Auto" /> 291.                    <RowDefinition Height="Auto" /> 292.                    <RowDefinition Height="Auto" /> 293.                </Grid.RowDefinitions> 294.                <Grid.ColumnDefinitions> 295.                    <ColumnDefinition Width="Auto" 296.                                      MinWidth="100" /> 297.                    <ColumnDefinition Width="Auto" 298.                                      MinWidth="200" /> 299.                </Grid.ColumnDefinitions> 300.                <!-- Subject --> 301.                <TextBlock x:Name="SubjectLabel" 302.                           Grid.Row="0" 303.                           Grid.Column="0" 304.                           Margin="0,15,0,2" 305.                           telerik:LocalizationManager.ResourceKey="Subject" 306.                           Style="{StaticResource FormElementTextBlockStyle}" /> 307.                <TextBox x:Name="Subject" 308.                         Grid.Row="0" 309.                         Grid.Column="1" 310.                         MinHeight="22" 311.                         Padding="4 2" 312.                         Width="340" 313.                         HorizontalAlignment="Left" 314.                         Text="{Binding Subject, Mode=TwoWay}" 315.                         MaxLength="255" 316.                         telerik:StyleManager.Theme="{StaticResource Theme}" 317.                         Margin="10,12,20,2" /> 318.                <!-- Description --> 319.                <TextBlock x:Name="DescriptionLabel" 320.                           Grid.Row="1" 321.                           Grid.Column="0" 322.                           Margin="0,13,0,2" 323.                           telerik:LocalizationManager.ResourceKey="Body" 324.                           Style="{StaticResource FormElementTextBlockStyle}" /> 325.                <TextBox x:Name="Body" 326.                         VerticalAlignment="top" 327.                         Grid.Row="1" 328.                         Grid.Column="1" 329.                         Height="Auto" 330.                         MaxHeight="82" 331.                         Width="340" 332.                         HorizontalAlignment="Left" 333.                         MinHeight="22" 334.                         Padding="4 2" 335.                         TextWrapping="Wrap" 336.                         telerik:StyleManager.Theme="{StaticResource Theme}" 337.                         Text="{Binding Body, Mode=TwoWay}" 338.                         AcceptsReturn="true" 339.                         Margin="10,10,20,2" 340.                         HorizontalScrollBarVisibility="Auto" 341.                         VerticalScrollBarVisibility="Auto" /> 342.                <!-- Start/End date --> 343.                <TextBlock x:Name="StartDateLabel" 344.                           Grid.Row="2" 345.                           Grid.Column="0" 346.                           Margin="0,13,0,2" 347.                           telerik:LocalizationManager.ResourceKey="StartTime" 348.                           Style="{StaticResource FormElementTextBlockStyle}" /> 349.                <telerikScheduler:DateTimePicker x:Name="StartDateTime" 350.                                                 Height="22" 351.                                                 Grid.Row="2" 352.                                                 Grid.Column="1" 353.                                                 HorizontalAlignment="Left" 354.                                                 Margin="10,10,20,2" 355.                                                 Style="{StaticResource FormElementStyle}" 356.                                                 SelectedDateTime="{Binding Start, Mode=TwoWay}" 357.                                                 telerikScheduler:StartEndDatePicker.EndPicker="{Binding ElementName=EndDateTime}" 358.                                                 IsTabStop="False" 359.                                                 IsEnabled="False" /> 360.                <TextBlock x:Name="EndDateLabel" 361.                           Grid.Row="3" 362.                           Grid.Column="0" 363.                           Margin="0,13,0,2" 364.                           telerik:LocalizationManager.ResourceKey="EndTime" 365.                           Style="{StaticResource FormElementTextBlockStyle}" /> 366.                <telerikScheduler:DateTimePicker x:Name="EndDateTime" 367.                                                 Height="22" 368.                                                 Grid.Row="3" 369.                                                 Grid.Column="1" 370.                                                 HorizontalAlignment="Left" 371.                                                 Margin="10,10,20,2" 372.                                                 Style="{StaticResource FormElementStyle}" 373.                                                 IsTabStop="False" 374.                                                 IsEnabled="False" 375.                                                 SelectedDateTime="{Binding End, Mode=TwoWay}" /> 376.                <!-- Is-all-day selector --> 377.                <CheckBox x:Name="AllDayEventCheckbox" 378.                          IsChecked="{Binding IsAllDayEvent, Mode=TwoWay}" 379.                          Grid.Row="4" 380.                          Grid.Column="1" 381.                          Margin="10,10,20,2" 382.                          HorizontalAlignment="Left" 383.                          telerik:StyleManager.Theme="{StaticResource Theme}" 384.                          telerik:LocalizationManager.ResourceKey="AllDayEvent"> 385.                    <telerik:CommandManager.InputBindings> 386.                        <telerik:InputBindingCollection> 387.                            <telerik:MouseBinding Command="telerikScheduler:RadSchedulerCommands.ChangeTimePickersVisibility" 388.                                                  Gesture="LeftClick" /> 389.                        </telerik:InputBindingCollection> 390.                    </telerik:CommandManager.InputBindings> 391.                </CheckBox> 392.                <Grid Grid.Row="5" 393.                      Grid.ColumnSpan="2"> 394.                    <Grid.ColumnDefinitions> 395.                        <ColumnDefinition Width="Auto" 396.                                          MinWidth="100" /> 397.                        <ColumnDefinition Width="Auto" 398.                                          MinWidth="200" /> 399.                    </Grid.ColumnDefinitions> 400.                    <Grid.RowDefinitions> 401.                        <RowDefinition Height="Auto" /> 402.                        <RowDefinition Height="Auto" /> 403.                    </Grid.RowDefinitions> 404.                    <TextBlock Text="Applicant" 405.                               Margin="0,13,0,2" 406.                               Style="{StaticResource FormElementTextBlockStyle}" /> 407.                    <telerikInput:RadComboBox IsEditable="False" 408.                                              Grid.Column="1" 409.                                              Height="24" 410.                                              VerticalAlignment="Center" 411.                                              ItemsSource="{Binding Source={StaticResource DataContextProxy}, Path=DataSource.ApplicantList}" 412.                                              SelectedValue="{Binding ApplicantID, Mode=TwoWay}" 413.                                              SelectedValuePath="ApplicantID" 414.                                              DisplayMemberPath="FirstName" /> 415.                       416.                    <TextBlock Text="Job" 417.                               Margin="0,13,0,2" 418.                               Grid.Row="1" 419.                               Style="{StaticResource FormElementTextBlockStyle}" /> 420.                    <telerikInput:RadComboBox IsEditable="False" 421.                                              Grid.Column="1" 422.                                              Grid.Row="1" 423.                                              Height="24" 424.                                              VerticalAlignment="Center" 425.                                              ItemsSource="{Binding Source={StaticResource DataContextProxy}, Path=DataSource.JobsList}" 426.                                              SelectedValue="{Binding PostingID, Mode=TwoWay}" 427.                                              SelectedValuePath="PostingID" 428.                                              DisplayMemberPath="JobTitle"/> 429.                </Grid> 430.                    <!-- Resources --> 431.                <Grid x:Name="ResourcesLayout" 432.                      Grid.Row="7" 433.                      Grid.Column="0" 434.                      Grid.ColumnSpan="2" 435.                      MaxHeight="130" 436.                      Margin="20,5,20,0"> 437.                    <Border Margin="0" 438.                            BorderThickness="1" 439.                            BorderBrush="{StaticResource GenericShallowBorderBrush}" 440.                            Visibility="{Binding ElementName=ResourcesScrollViewer, Path=ComputedVerticalScrollBarVisibility}"></Border> 441.                    <ScrollViewer x:Name="ResourcesScrollViewer" 442.                                  IsTabStop="false" 443.                                  Grid.Row="6" 444.                                  Grid.Column="0" 445.                                  Grid.ColumnSpan="2" 446.                                  Margin="1" 447.                                  telerik:StyleManager.Theme="{StaticResource Theme}" 448.                                  VerticalScrollBarVisibility="Auto"> 449.                        <scheduler:ResourcesItemsControl x:Name="PART_Resources" 450.                                                         HorizontalAlignment="Left" 451.                                                         Padding="0,2,0,5" 452.                                                         IsTabStop="false" 453.                                                         ItemsSource="{TemplateBinding ResourceTypeModels}" 454.                                                         ItemTemplateSelector="{StaticResource ItemTemplateSelector}" /> 455.                    </ScrollViewer> 456.                </Grid> 457.                <StackPanel x:Name="FooterControls" 458.                            Margin="5 10 10 10" 459.                            Grid.Row="8" 460.                            Grid.Column="1" 461.                            HorizontalAlignment="Left" 462.                            Orientation="Horizontal"> 463.                    <telerik:RadButton x:Name="OKButton" 464.                                       Margin="5" 465.                                       Padding="10 0" 466.                                       MinWidth="80" 467.                                       Command="telerikScheduler:RadSchedulerCommands.SaveAppointment" 468.                                       telerik:StyleManager.Theme="{StaticResource Theme}" 469.                                       telerikNavigation:RadWindow.ResponseButton="Accept" 470.                                       telerik:LocalizationManager.ResourceKey="SaveAndCloseCommandText"> 471.                    </telerik:RadButton> 472.                    <telerik:RadButton x:Name="CancelButton" 473.                                       Margin="5" 474.                                       Padding="10 0" 475.                                       MinWidth="80" 476.                                       telerik:LocalizationManager.ResourceKey="Cancel" 477.                                       telerik:StyleManager.Theme="{StaticResource Theme}" 478.                                       telerikNavigation:RadWindow.ResponseButton="Cancel" 479.                                       Command="telerik:WindowCommands.Close"> 480.                    </telerik:RadButton> 481.                </StackPanel> 482.            </Grid> 483.            <vsm:VisualStateManager.VisualStateGroups> 484.                <vsm:VisualStateGroup x:Name="RecurrenceRuleState"> 485.                    <vsm:VisualState x:Name="RecurrenceRuleIsNull"> 486.                        <Storyboard> 487.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="StartDateTime" 488.                                                           Storyboard.TargetProperty="IsEnabled" 489.                                                           Duration="0"> 490.                                <DiscreteObjectKeyFrame KeyTime="0" 491.                                                        Value="True" /> 492.                            </ObjectAnimationUsingKeyFrames> 493.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="EndDateTime" 494.                                                           Storyboard.TargetProperty="IsEnabled" 495.                                                           Duration="0"> 496.                                <DiscreteObjectKeyFrame KeyTime="0" 497.                                                        Value="True" /> 498.                            </ObjectAnimationUsingKeyFrames> 499.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="AllDayEventCheckbox" 500.                                                           Storyboard.TargetProperty="IsEnabled" 501.                                                           Duration="0"> 502.                                <DiscreteObjectKeyFrame KeyTime="0" 503.                                                        Value="True" /> 504.                            </ObjectAnimationUsingKeyFrames> 505.                        </Storyboard> 506.                    </vsm:VisualState> 507.                    <vsm:VisualState x:Name="RecurrenceRuleIsNotNull"> 508.                        <Storyboard> 509.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="StartDateTime" 510.                                                           Storyboard.TargetProperty="IsEnabled" 511.                                                           Duration="0"> 512.                                <DiscreteObjectKeyFrame KeyTime="0" 513.                                                        Value="False" /> 514.                            </ObjectAnimationUsingKeyFrames> 515.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="EndDateTime" 516.                                                           Storyboard.TargetProperty="IsEnabled" 517.                                                           Duration="0"> 518.                                <DiscreteObjectKeyFrame KeyTime="0" 519.                                                        Value="False" /> 520.                            </ObjectAnimationUsingKeyFrames> 521.                            <ObjectAnimationUsingKeyFrames Storyboard.TargetName="AllDayEventCheckbox" 522.                                                           Storyboard.TargetProperty="IsEnabled" 523.                                                           Duration="0"> 524.                                <DiscreteObjectKeyFrame KeyTime="0" 525.                                                        Value="False" /> 526.                            </ObjectAnimationUsingKeyFrames> 527.                        </Storyboard> 528.                    </vsm:VisualState> 529.                </vsm:VisualStateGroup> 530.            </vsm:VisualStateManager.VisualStateGroups> 531.        </StackPanel> 532.    </ControlTemplate> 533.    <DataTemplate x:Key="AppointmentDialogWindowHeaderDataTemplate"> 534.        <StackPanel Orientation="Horizontal" 535.                    MaxWidth="400"> 536.            <TextBlock telerik:LocalizationManager.ResourceKey="Event" 537.                       Visibility="{Binding Appointment.IsAllDayEvent, Converter={StaticResource BooleanToVisibilityConverter}}" /> 538.            <TextBlock telerik:LocalizationManager.ResourceKey="Appointment" 539.                       Visibility="{Binding Appointment.IsAllDayEvent, Converter={StaticResource InvertedBooleanToVisibilityConverter}}" /> 540.            <TextBlock Text=" - " /> 541.            <TextBlock x:Name="SubjectTextBlock" 542.                       Visibility="{Binding Appointment.Subject, Converter={StaticResource NullToVisibilityConverter}}" 543.                       Text="{Binding Appointment.Subject}" /> 544.            <TextBlock telerik:LocalizationManager.ResourceKey="Untitled" 545.                       Visibility="{Binding Appointment.Subject, Converter={StaticResource InvertedNullToVisibilityConverter}}" /> 546.        </StackPanel> 547.    </DataTemplate> 548.    <Style x:Key="EditAppointmentStyle" 549.           TargetType="telerikScheduler:AppointmentDialogWindow"> 550.        <Setter Property="IconTemplate" 551.                Value="{StaticResource IconDataEditTemplate}" /> 552.        <Setter Property="HeaderTemplate" 553.                Value="{StaticResource AppointmentDialogWindowHeaderDataTemplate}" /> 554.        <Setter Property="Background" 555.                Value="{StaticResource DialogWindowBackground}" /> 556.        <Setter Property="Template" 557.                Value="{StaticResource EditAppointmentTemplate}" /> 558.    </Style> 559.</UserControl.Resources> The first line there is the DataContextProxy I mentioned previously- we use that again to work a bit of magic in this template. Where we start getting into the dialog in question is line 132, but line 407 is where things start getting interesting.  The ItemsSource is pointing at a list that exists in my ViewModel (or code-behind, if it is used as a DataContext), the SelectedValue is the item I am actually binding from the applicant (note the TwoWay binding), and SelectedValuePath and DisplayMemberPath ensure the proper applicant is being displayed from the collection.  You will also see similar starting on line 420 where I do the same for the Jobs we'll be displaying. Just to wrap-up the Xaml, here's the RadScheduler declaraction that ties this all together and will be the main focus of our view: 01.<telerikScheduler:RadScheduler x:Name="xJobsScheduler" 02.                  Grid.Row="1" 03.                  Grid.Column="1" 04.                  Width="800" 05.                  MinWidth="600" 06.                  Height="500" 07.                  MinHeight="300" 08.                  AppointmentsSource="{Binding Interviews}" 09.                  EditAppointmentStyle="{StaticResource EditAppointmentStyle}" 10.                  command:AppointmentAddedEventClass.Command="{Binding AddAppointmentCommand}" 11.                  command:ApptCreatedEventClass.Command="{Binding ApptCreatingCommand}" 12.                  command:ApptEditedEventClass.Command="{Binding ApptEditedCommand}" 13.                  command:ApptDeletedEventClass.Command="{Binding ApptDeletedCommand}"> 14.</telerikScheduler:RadScheduler> Now, we get to the ViewModel and what it takes to get that rigged up.  And for those of you who remember the jobs post, those command:s in the Xaml are pointing to attached behavior commands that reproduce the respective events.  This becomes very handy when we're setting up the code-behind version. ;) ViewModel I've been liking this approach so far, so I'm going to put the entire ViewModel here and then go into the lines of interest.  Of course, feel free to ask me questions about anything that isn't clear (by line number, ideally) so I can help out if I have missed anything important: 001.public class SchedulerViewModel : ViewModelBase 002.{ 003.    private readonly IEventAggregator eventAggregator; 004.    private readonly IRegionManager regionManager; 005.   006.    public RecruitingContext context; 007.   008.    private ObservableItemCollection<InterviewAppointment> _interviews = new ObservableItemCollection<InterviewAppointment>(); 009.    public ObservableItemCollection<InterviewAppointment> Interviews 010.    { 011.        get { return _interviews; } 012.        set 013.        { 014.            if (_interviews != value) 015.            { 016.                _interviews = value; 017.                NotifyChanged("Interviews"); 018.            } 019.        } 020.    } 021.   022.    private QueryableCollectionView _jobsList; 023.    public QueryableCollectionView JobsList 024.    { 025.        get { return this._jobsList; } 026.        set 027.        { 028.            if (this._jobsList != value) 029.            { 030.                this._jobsList = value; 031.                this.NotifyChanged("JobsList"); 032.            } 033.        } 034.    } 035.   036.    private QueryableCollectionView _applicantList; 037.    public QueryableCollectionView ApplicantList 038.    { 039.        get { return _applicantList; } 040.        set 041.        { 042.            if (_applicantList != value) 043.            { 044.                _applicantList = value; 045.                NotifyChanged("ApplicantList"); 046.            } 047.        } 048.    } 049.   050.    public DelegateCommand<object> AddAppointmentCommand { get; set; } 051.    public DelegateCommand<object> ApptCreatingCommand { get; set; } 052.    public DelegateCommand<object> ApptEditedCommand { get; set; } 053.    public DelegateCommand<object> ApptDeletedCommand { get; set; } 054.   055.    public SchedulerViewModel(IEventAggregator eventAgg, IRegionManager regionmanager) 056.    { 057.        // set Unity items 058.        this.eventAggregator = eventAgg; 059.        this.regionManager = regionmanager; 060.   061.        // load our context 062.        context = new RecruitingContext(); 063.        LoadOperation<Interview> loadOp = context.Load(context.GetInterviewsQuery()); 064.        loadOp.Completed += new EventHandler(loadOp_Completed); 065.   066.        this._jobsList = new QueryableCollectionView(context.JobPostings); 067.        context.Load(context.GetJobPostingsQuery()); 068.   069.        this._applicantList = new QueryableCollectionView(context.Applicants); 070.        context.Load(context.GetApplicantsQuery()); 071.   072.        AddAppointmentCommand = new DelegateCommand<object>(this.AddAppt); 073.        ApptCreatingCommand = new DelegateCommand<object>(this.ApptCreating); 074.        ApptEditedCommand = new DelegateCommand<object>(this.ApptEdited); 075.        ApptDeletedCommand = new DelegateCommand<object>(this.ApptDeleted); 076.   077.    } 078.   079.    void loadOp_Completed(object sender, EventArgs e) 080.    { 081.        LoadOperation loadop = sender as LoadOperation; 082.   083.        foreach (var ent in loadop.Entities) 084.        { 085.            _interviews.Add(EntityToAppointment(ent as Interview)); 086.        } 087.    } 088.   089.    #region Appointment Adding 090.   091.    public void AddAppt(object obj) 092.    { 093.        // now we have a new InterviewAppointment to add to our QCV :) 094.        InterviewAppointment newInterview = obj as InterviewAppointment; 095.   096.        this.context.Interviews.Add(AppointmentToEntity(newInterview)); 097.        this.context.SubmitChanges((s) => 098.        { 099.            ActionHistory myAction = new ActionHistory(); 100.            myAction.InterviewID = newInterview.InterviewID; 101.            myAction.PostingID = newInterview.PostingID; 102.            myAction.ApplicantID = newInterview.ApplicantID; 103.            myAction.Description = String.Format("Interview with {0} has been created by {1}", newInterview.ApplicantID.ToString(), "default user"); 104.            myAction.TimeStamp = DateTime.Now; 105.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 106.        } 107.            , null); 108.    } 109.   110.    public void ApptCreating(object obj) 111.    { 112.        // handled in the behavior, just a placeholder to ensure it runs :) 113.    } 114.   115.    #endregion 116.   117.    #region Appointment Editing 118.   119.    public void ApptEdited(object obj) 120.    { 121.        Interview editedInterview = (from x in context.Interviews 122.                            where x.InterviewID == (obj as InterviewAppointment).InterviewID 123.                            select x).SingleOrDefault(); 124.   125.        CopyAppointmentEdit(editedInterview, obj as InterviewAppointment); 126.   127.        context.SubmitChanges((s) => { 128.            ActionHistory myAction = new ActionHistory(); 129.            myAction.InterviewID = editedInterview.InterviewID; 130.            myAction.PostingID = editedInterview.PostingID; 131.            myAction.ApplicantID = editedInterview.ApplicantID; 132.            myAction.Description = String.Format("Interview with {0} has been modified by {1}", editedInterview.ApplicantID.ToString(), "default user"); 133.            myAction.TimeStamp = DateTime.Now; 134.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); } 135.            , null); 136.    } 137.   138.    #endregion 139.   140.    #region Appointment Deleting 141.   142.    public void ApptDeleted(object obj) 143.    { 144.        Interview deletedInterview = (from x in context.Interviews 145.                                      where x.InterviewID == (obj as InterviewAppointment).InterviewID 146.                                      select x).SingleOrDefault(); 147.   148.        context.Interviews.Remove(deletedInterview); 149.        context.SubmitChanges((s) => 150.        { 151.            ActionHistory myAction = new ActionHistory(); 152.            myAction.InterviewID = deletedInterview.InterviewID; 153.            myAction.PostingID = deletedInterview.PostingID; 154.            myAction.ApplicantID = deletedInterview.ApplicantID; 155.            myAction.Description = String.Format("Interview with {0} has been deleted by {1}", deletedInterview.ApplicantID.ToString(), "default user"); 156.            myAction.TimeStamp = DateTime.Now; 157.            eventAggregator.GetEvent<AddActionEvent>().Publish(myAction); 158.        } 159.            , null); 160.    } 161.   162.    #endregion 163.   164.    #region Appointment Helpers :) 165.   166.    public Interview AppointmentToEntity(InterviewAppointment ia) 167.    { 168.        Interview newInterview = new Interview(); 169.        newInterview.Subject = ia.Subject; 170.        newInterview.Body = ia.Body; 171.        newInterview.Start = ia.Start; 172.        newInterview.End = ia.End; 173.        newInterview.ApplicantID = ia.ApplicantID; 174.        newInterview.PostingID = ia.PostingID; 175.        newInterview.InterviewID = ia.InterviewID; 176.   177.        return newInterview; 178.    } 179.   180.    public InterviewAppointment EntityToAppointment(Interview ia) 181.    { 182.        InterviewAppointment newInterview = new InterviewAppointment(); 183.        newInterview.Subject = ia.Subject; 184.        newInterview.Body = ia.Body; 185.        newInterview.Start = ia.Start; 186.        newInterview.End = ia.End; 187.        newInterview.ApplicantID = ia.ApplicantID; 188.        newInterview.PostingID = ia.PostingID; 189.        newInterview.InterviewID = ia.InterviewID; 190.   191.        return newInterview; 192.    } 193.   194.    public void CopyAppointmentEdit(Interview entityInterview, InterviewAppointment appointmentInterview) 195.    { 196.        entityInterview.Subject = appointmentInterview.Subject; 197.        entityInterview.Body = appointmentInterview.Body; 198.        entityInterview.Start = appointmentInterview.Start; 199.        entityInterview.End = appointmentInterview.End; 200.        entityInterview.ApplicantID = appointmentInterview.ApplicantID; 201.        entityInterview.PostingID = appointmentInterview.PostingID; 202.    } 203.   204.    #endregion 205.} One thing we're doing here which you won't see in any of the other ViewModels is creating a duplicate collection.  I know this is something which will be fixed down the line for using RadScheduler, simplifying this process, but with WCF RIA changing as it does I wanted to ensure functionality would remain consistent as I continued development on this application.  So, I do a little bit of duplication, but for the greater good.  This all takes place starting on line 79, so for every entity that comes back we add it to the collection that is bound to RadScheduler.  Otherwise, the DelegateCommands that you see correspond directly to the events they are named after.  In each case, rather than sending over the full event arguments, I just send in the appointment in question (coming through as the object obj in all cases) so I can add (line 91), edit (line 119), and delete appointments (line 142) like normal.  This just ensures they get updated back to my database.  Also, the one bit of code you won't see is for the Appointment Creating (line 110) event- that is because in the command I've created I simply make the replacement I need to: 1.void element_AppointmentCreating(object sender, AppointmentCreatingEventArgs e) 2.{ 3.    e.NewAppointment = new InterviewAppointment(); 4.    base.ExecuteCommand(); 5.} And the ViewModel is none the wiser, the appointments just work as far as it is concerned since as they are created they become InterviewAppointments.  End result?  I've customized my EditAppointmentDialog as follows: And adding, editing, and deleting appointments works like a charm.  I can even 'edit' by moving appointments around RadScheduler, so as they are dropped into a timeslot they perform their full edit routine and things get updated. And then, the Code-Behind Version Perhaps the thing I like the most about doing one then the other is I get to steal 90% or more of the code from the MVVM version.  For example, the only real changes to the Code-Behind Xaml file exist in the control declaration, in which I use events instead of attached-behavior-event-commands: 01.<telerikScheduler:RadScheduler x:Name="xJobsScheduler" 02.                  Grid.Row="1" 03.                  Grid.Column="1" 04.                  Width="800" 05.                  MinWidth="600" 06.                  Height="500" 07.                  MinHeight="300" 08.                  EditAppointmentStyle="{StaticResource EditAppointmentStyle}" 09.                  AppointmentAdded="xJobsScheduler_AppointmentAdded" 10.                  AppointmentCreating="xJobsScheduler_AppointmentCreating" 11.                  AppointmentEdited="xJobsScheduler_AppointmentEdited" 12.                  AppointmentDeleted="xJobsScheduler_AppointmentDeleted"> 13.</telerikScheduler:RadScheduler> Easy, right?  Otherwise, all the same styling in UserControl.Resources was re-used, right down to the DataContextProxy that lets us bind to a collection from our viewmodel (in this case, our code-behind) to use within the DataTemplate.  The code conversion gets even easier, as I could literally copy and paste almost everything from the ViewModel to my Code-Behind, just a matter of pasting the right section into the right event.  Here's the code-behind as proof: 001.public partial class SchedulingView : UserControl, INotifyPropertyChanged 002.{ 003.    public RecruitingContext context; 004.   005.    private QueryableCollectionView _jobsList; 006.    public QueryableCollectionView JobsList 007.    { 008.        get { return this._jobsList; } 009.        set 010.        { 011.            if (this._jobsList != value) 012.            { 013.                this._jobsList = value; 014.                this.NotifyChanged("JobsList"); 015.            } 016.        } 017.    } 018.   019.    private QueryableCollectionView _applicantList; 020.    public QueryableCollectionView ApplicantList 021.    { 022.        get { return _applicantList; } 023.        set 024.        { 025.            if (_applicantList != value) 026.            { 027.                _applicantList = value; 028.                NotifyChanged("ApplicantList"); 029.            } 030.        } 031.    } 032.   033.    private ObservableItemCollection<InterviewAppointment> _interviews = new ObservableItemCollection<InterviewAppointment>(); 034.    public ObservableItemCollection<InterviewAppointment> Interviews 035.    { 036.        get { return _interviews; } 037.        set 038.        { 039.            if (_interviews != value) 040.            { 041.                _interviews = value; 042.                NotifyChanged("Interviews"); 043.            } 044.        } 045.    } 046.   047.    public SchedulingView() 048.    { 049.        InitializeComponent(); 050.   051.        this.DataContext = this; 052.   053.        this.Loaded += new RoutedEventHandler(SchedulingView_Loaded); 054.    } 055.   056.    void SchedulingView_Loaded(object sender, RoutedEventArgs e) 057.    { 058.        this.xJobsScheduler.AppointmentsSource = Interviews; 059.   060.        context = new RecruitingContext(); 061.           062.        LoadOperation loadop = context.Load(context.GetInterviewsQuery()); 063.        loadop.Completed += new EventHandler(loadop_Completed); 064.   065.        this._applicantList = new QueryableCollectionView(context.Applicants); 066.        context.Load(context.GetApplicantsQuery()); 067.   068.        this._jobsList = new QueryableCollectionView(context.JobPostings); 069.        context.Load(context.GetJobPostingsQuery()); 070.    } 071.   072.    void loadop_Completed(object sender, EventArgs e) 073.    { 074.        LoadOperation loadop = sender as LoadOperation; 075.   076.        _interviews.Clear(); 077.   078.        foreach (var ent in loadop.Entities) 079.        { 080.            _interviews.Add(EntityToAppointment(ent as Interview)); 081.        } 082.    } 083.   084.    private void xJobsScheduler_AppointmentAdded(object sender, Telerik.Windows.Controls.AppointmentAddedEventArgs e) 085.    { 086.        // now we have a new InterviewAppointment to add to our QCV :) 087.        InterviewAppointment newInterview = e.Appointment as InterviewAppointment; 088.   089.        this.context.Interviews.Add(AppointmentToEntity(newInterview)); 090.        this.context.SubmitChanges((s) => 091.        { 092.            ActionHistory myAction = new ActionHistory(); 093.            myAction.InterviewID = newInterview.InterviewID; 094.            myAction.PostingID = newInterview.PostingID; 095.            myAction.ApplicantID = newInterview.ApplicantID; 096.            myAction.Description = String.Format("Interview with {0} has been created by {1}", newInterview.ApplicantID.ToString(), "default user"); 097.            myAction.TimeStamp = DateTime.Now; 098.            context.ActionHistories.Add(myAction); 099.            context.SubmitChanges(); 100.        } 101.            , null); 102.    } 103.   104.    private void xJobsScheduler_AppointmentCreating(object sender, Telerik.Windows.Controls.AppointmentCreatingEventArgs e) 105.    { 106.        e.NewAppointment = new InterviewAppointment(); 107.    } 108.   109.    private void xJobsScheduler_AppointmentEdited(object sender, Telerik.Windows.Controls.AppointmentEditedEventArgs e) 110.    { 111.        Interview editedInterview = (from x in context.Interviews 112.                                     where x.InterviewID == (e.Appointment as InterviewAppointment).InterviewID 113.                                     select x).SingleOrDefault(); 114.   115.        CopyAppointmentEdit(editedInterview, e.Appointment as InterviewAppointment); 116.   117.        context.SubmitChanges((s) => 118.        { 119.            ActionHistory myAction = new ActionHistory(); 120.            myAction.InterviewID = editedInterview.InterviewID; 121.            myAction.PostingID = editedInterview.PostingID; 122.            myAction.ApplicantID = editedInterview.ApplicantID; 123.            myAction.Description = String.Format("Interview with {0} has been modified by {1}", editedInterview.ApplicantID.ToString(), "default user"); 124.            myAction.TimeStamp = DateTime.Now; 125.            context.ActionHistories.Add(myAction); 126.            context.SubmitChanges(); 127.        } 128.            , null); 129.    } 130.   131.    private void xJobsScheduler_AppointmentDeleted(object sender, Telerik.Windows.Controls.AppointmentDeletedEventArgs e) 132.    { 133.        Interview deletedInterview = (from x in context.Interviews 134.                                      where x.InterviewID == (e.Appointment as InterviewAppointment).InterviewID 135.                                      select x).SingleOrDefault(); 136.   137.        context.Interviews.Remove(deletedInterview); 138.        context.SubmitChanges((s) => 139.        { 140.            ActionHistory myAction = new ActionHistory(); 141.            myAction.InterviewID = deletedInterview.InterviewID; 142.            myAction.PostingID = deletedInterview.PostingID; 143.            myAction.ApplicantID = deletedInterview.ApplicantID; 144.            myAction.Description = String.Format("Interview with {0} has been deleted by {1}", deletedInterview.ApplicantID.ToString(), "default user"); 145.            myAction.TimeStamp = DateTime.Now; 146.            context.ActionHistories.Add(myAction); 147.            context.SubmitChanges(); 148.        } 149.            , null); 150.    } 151.   152.    #region Appointment Helpers :) 153.   154.    public Interview AppointmentToEntity(InterviewAppointment ia) 155.    { 156.        Interview newInterview = new Interview(); 157.        newInterview.Subject = ia.Subject; 158.        newInterview.Body = ia.Body; 159.        newInterview.Start = ia.Start; 160.        newInterview.End = ia.End; 161.        newInterview.ApplicantID = ia.ApplicantID; 162.        newInterview.PostingID = ia.PostingID; 163.        newInterview.InterviewID = ia.InterviewID; 164.   165.        return newInterview; 166.    } 167.   168.    public InterviewAppointment EntityToAppointment(Interview ia) 169.    { 170.        InterviewAppointment newInterview = new InterviewAppointment(); 171.        newInterview.Subject = ia.Subject; 172.        newInterview.Body = ia.Body; 173.        newInterview.Start = ia.Start; 174.        newInterview.End = ia.End; 175.        newInterview.ApplicantID = ia.ApplicantID; 176.        newInterview.PostingID = ia.PostingID; 177.        newInterview.InterviewID = ia.InterviewID; 178.   179.        return newInterview; 180.    } 181.   182.    public void CopyAppointmentEdit(Interview entityInterview, InterviewAppointment appointmentInterview) 183.    { 184.        entityInterview.Subject = appointmentInterview.Subject; 185.        entityInterview.Body = appointmentInterview.Body; 186.        entityInterview.Start = appointmentInterview.Start; 187.        entityInterview.End = appointmentInterview.End; 188.        entityInterview.ApplicantID = appointmentInterview.ApplicantID; 189.        entityInterview.PostingID = appointmentInterview.PostingID; 190.    } 191.   192.    #endregion 193.   194.    #region INotifyPropertyChanged Members 195.   196.    public event PropertyChangedEventHandler PropertyChanged; 197.   198.    public void NotifyChanged(string propertyName) 199.    { 200.        if (string.IsNullOrEmpty(propertyName)) 201.            throw new ArgumentException("propertyName"); 202.   203.        PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); 204.    } 205.   206.    #endregion 207.} Nice... right? :) One really important thing to note as well.  See on line 51 where I set the DataContext before the Loaded event?  This is super important, as if you don't have this set before the usercontrol is loaded, the DataContextProxy has no context to use and your EditAppointmentDialog Job/Applicant dropdowns will be blank and empty.  Trust me on this, took a little bit of debugging to figure out that by setting the DataContext post-loaded would only lead to disaster and frustration.  Otherwise, the only other real difference is that instead of sending an ActionHistory item through an event to get added to the database and saved, I do those right in the callback from submitting.  The Result Again, I only have to post one picture because these bad boys used nearly identical code for both the MVVM and the code-behind views, so our end result is... So what have we learned here today?  One, for the most part this MVVM thing is somewhat easy.  Yeah, you sometimes have to write a bunch of extra code, but with the help of a few useful snippits you can turn the process into a pretty streamlined little workflow.  Heck, this story gets even easier as you can see in this blog post by Michael Washington- specifically run a find on 'InvokeCommandAction' and you'll see the section regarding the command on TreeView in Blend 4.  Brilliant!  MVVM never looked so sweet! Otherwise, it is business as usual with RadScheduler for Silverlight whichever path you're choosing for your development.  Between now and the next post, I'll be cleaning up styles a bit (those RadComboBoxes are a little too close to my labels!) and adding some to the RowDetailsViews for Applicants and Jobs, so you can see all the info for an appointment in the dropdown tab view.  Otherwise, we're about ready to call a wrap on this oneDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Creating STA COM compatible ASP.NET Applications

  - by Rick Strahl

  When building ASP.NET applications that interface with old school COM objects like those created with VB6 or Visual FoxPro (MTDLL), it's extremely important that the threads that are serving requests use Single Threaded Apartment Threading. STA is a COM built-in technology that allows essentially single threaded components to operate reliably in a multi-threaded environment. STA's guarantee that COM objects instantiated on a specific thread stay on that specific thread and any access to a COM object from another thread automatically marshals that thread to the STA thread. The end effect is that you can have multiple threads, but a COM object instance lives on a fixed never changing thread. ASP.NET by default uses MTA (multi-threaded apartment) threads which are truly free spinning threads that pay no heed to COM object marshaling. This is vastly more efficient than STA threading which has a bit of overhead in determining whether it's OK to run code on a given thread or whether some sort of thread/COM marshaling needs to occur. MTA COM components can be very efficient, but STA COM components in a multi-threaded environment always tend to have a fair amount of overhead. It's amazing how much COM Interop I still see today so while it seems really old school to be talking about this topic, it's actually quite apropos for me as I have many customers using legacy COM systems that need to interface with other .NET applications. In this post I'm consolidating some of the hacks I've used to integrate with various ASP.NET technologies when using STA COM Components. STA in ASP.NET Support for STA threading in the ASP.NET framework is fairly limited. Specifically only the original ASP.NET WebForms technology supports STA threading directly via its STA Page Handler implementation or what you might know as ASPCOMPAT mode. For WebForms running STA components is as easy as specifying the ASPCOMPAT attribute in the @Page tag:<%@ Page Language="C#" AspCompat="true" %> which runs the page in STA mode. Removing it runs in MTA mode. Simple. Unfortunately all other ASP.NET technologies built on top of the core ASP.NET engine do not support STA natively. So if you want to use STA COM components in MVC or with class ASMX Web Services, there's no automatic way like the ASPCOMPAT keyword available. So what happens when you run an STA COM component in an MTA application? In low volume environments - nothing much will happen. The COM objects will appear to work just fine as there are no simultaneous thread interactions and the COM component will happily run on a single thread or multiple single threads one at a time. So for testing running components in MTA environments may appear to work just fine. However as load increases and threads get re-used by ASP.NET COM objects will end up getting created on multiple different threads. This can result in crashes or hangs, or data corruption in the STA components which store their state in thread local storage on the STA thread. If threads overlap this global store can easily get corrupted which in turn causes problems. STA ensures that any COM object instance loaded always stays on the same thread it was instantiated on. What about COM+? COM+ is supposed to address the problem of STA in MTA applications by providing an abstraction with it's own thread pool manager for COM objects. It steps in to the COM instantiation pipeline and hands out COM instances from its own internally maintained STA Thread pool. This guarantees that the COM instantiation threads are STA threads if using STA components. COM+ works, but in my experience the technology is very, very slow for STA components. It adds a ton of overhead and reduces COM performance noticably in load tests in IIS. COM+ can make sense in some situations but for Web apps with STA components it falls short. In addition there's also the need to ensure that COM+ is set up and configured on the target machine and the fact that components have to be registered in COM+. COM+ also keeps components up at all times, so if a component needs to be replaced the COM+ package needs to be unloaded (same is true for IIS hosted components but it's more common to manage that). COM+ is an option for well established components, but native STA support tends to provide better performance and more consistent usability, IMHO. STA for non supporting ASP.NET Technologies As mentioned above only WebForms supports STA natively. However, by utilizing the WebForms ASP.NET Page handler internally it's actually possible to trick various other ASP.NET technologies and let them work with STA components. This is ugly but I've used each of these in various applications and I've had minimal problems making them work with FoxPro STA COM components which is about as dififcult as it gets for COM Interop in .NET. In this post I summarize several STA workarounds that enable you to use STA threading with these ASP.NET Technologies: ASMX Web Services ASP.NET MVC WCF Web Services ASP.NET Web API ASMX Web Services I start with classic ASP.NET ASMX Web Services because it's the easiest mechanism that allows for STA modification. It also clearly demonstrates how the WebForms STA Page Handler is the key technology to enable the various other solutions to create STA components. Essentially the way this works is to override the WebForms Page class and hijack it's init functionality for processing requests. Here's what this looks like for Web Services:namespace FoxProAspNet { public class WebServiceStaHandler : System.Web.UI.Page, IHttpAsyncHandler { protected override void OnInit(EventArgs e) { IHttpHandler handler = new WebServiceHandlerFactory().GetHandler( this.Context, this.Context.Request.HttpMethod, this.Context.Request.FilePath, this.Context.Request.PhysicalPath); handler.ProcessRequest(this.Context); this.Context.ApplicationInstance.CompleteRequest(); } public IAsyncResult BeginProcessRequest( HttpContext context, AsyncCallback cb, object extraData) { return this.AspCompatBeginProcessRequest(context, cb, extraData); } public void EndProcessRequest(IAsyncResult result) { this.AspCompatEndProcessRequest(result); } } public class AspCompatWebServiceStaHandlerWithSessionState : WebServiceStaHandler, IRequiresSessionState { } } This class overrides the ASP.NET WebForms Page class which has a little known AspCompatBeginProcessRequest() and AspCompatEndProcessRequest() method that is responsible for providing the WebForms ASPCOMPAT functionality. These methods handle routing requests to STA threads. Note there are two classes - one that includes session state and one that does not. If you plan on using ASP.NET Session state use the latter class, otherwise stick to the former. This maps to the EnableSessionState page setting in WebForms. This class simply hooks into this functionality by overriding the BeginProcessRequest and EndProcessRequest methods and always forcing it into the AspCompat methods. The way this works is that BeginProcessRequest() fires first to set up the threads and starts intializing the handler. As part of that process the OnInit() method is fired which is now already running on an STA thread. The code then creates an instance of the actual WebService handler factory and calls its ProcessRequest method to start executing which generates the Web Service result. Immediately after ProcessRequest the request is stopped with Application.CompletRequest() which ensures that the rest of the Page handler logic doesn't fire. This means that even though the fairly heavy Page class is overridden here, it doesn't end up executing any of its internal processing which makes this code fairly efficient. In a nutshell, we're highjacking the Page HttpHandler and forcing it to process the WebService process handler in the context of the AspCompat handler behavior. Hooking up the Handler Because the above is an HttpHandler implementation you need to hook up the custom handler and replace the standard ASMX handler. To do this you need to modify the web.config file (here for IIS 7 and IIS Express): <configuration> <system.webServer> <handlers> <remove name="WebServiceHandlerFactory-Integrated-4.0" /> <add name="Asmx STA Web Service Handler" path="*.asmx" verb="*" type="FoxProAspNet.WebServiceStaHandler" precondition="integrated"/> </handlers> </system.webServer> </configuration> (Note: The name for the WebServiceHandlerFactory-Integrated-4.0 might be slightly different depending on your server version. Check the IIS Handler configuration in the IIS Management Console for the exact name or simply remove the handler from the list there which will propagate to your web.config). For IIS 5 & 6 (Windows XP/2003) or the Visual Studio Web Server use:<configuration> <system.web> <httpHandlers> <remove path="*.asmx" verb="*" /> <add path="*.asmx" verb="*" type="FoxProAspNet.WebServiceStaHandler" /> </httpHandlers> </system.web></configuration> To test, create a new ASMX Web Service and create a method like this: [WebService(Namespace = "http://foxaspnet.org/")] [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] public class FoxWebService : System.Web.Services.WebService { [WebMethod] public string HelloWorld() { return "Hello World. Threading mode is: " + System.Threading.Thread.CurrentThread.GetApartmentState(); } } Run this before you put in the web.config configuration changes and you should get: Hello World. Threading mode is: MTA Then put the handler mapping into Web.config and you should see: Hello World. Threading mode is: STA And you're on your way to using STA COM components. It's a hack but it works well! I've used this with several high volume Web Service installations with various customers and it's been fast and reliable. ASP.NET MVC ASP.NET MVC has quickly become the most popular ASP.NET technology, replacing WebForms for creating HTML output. MVC is more complex to get started with, but once you understand the basic structure of how requests flow through the MVC pipeline it's easy to use and amazingly flexible in manipulating HTML requests. In addition, MVC has great support for non-HTML output sources like JSON and XML, making it an excellent choice for AJAX requests without any additional tools. Unlike WebForms ASP.NET MVC doesn't support STA threads natively and so some trickery is needed to make it work with STA threads as well. MVC gets its handler implementation through custom route handlers using ASP.NET's built in routing semantics. To work in an STA handler requires working in the Page Handler as part of the Route Handler implementation. As with the Web Service handler the first step is to create a custom HttpHandler that can instantiate an MVC request pipeline properly:public class MvcStaThreadHttpAsyncHandler : Page, IHttpAsyncHandler, IRequiresSessionState { private RequestContext _requestContext; public MvcStaThreadHttpAsyncHandler(RequestContext requestContext) { if (requestContext == null) throw new ArgumentNullException("requestContext"); _requestContext = requestContext; } public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData) { return this.AspCompatBeginProcessRequest(context, cb, extraData); } protected override void OnInit(EventArgs e) { var controllerName = _requestContext.RouteData.GetRequiredString("controller"); var controllerFactory = ControllerBuilder.Current.GetControllerFactory(); var controller = controllerFactory.CreateController(_requestContext, controllerName); if (controller == null) throw new InvalidOperationException("Could not find controller: " + controllerName); try { controller.Execute(_requestContext); } finally { controllerFactory.ReleaseController(controller); } this.Context.ApplicationInstance.CompleteRequest(); } public void EndProcessRequest(IAsyncResult result) { this.AspCompatEndProcessRequest(result); } public override void ProcessRequest(HttpContext httpContext) { throw new NotSupportedException("STAThreadRouteHandler does not support ProcessRequest called (only BeginProcessRequest)"); } } This handler code figures out which controller to load and then executes the controller. MVC internally provides the information needed to route to the appropriate method and pass the right parameters. Like the Web Service handler the logic occurs in the OnInit() and performs all the processing in that part of the request. Next, we need a RouteHandler that can actually pick up this handler. Unlike the Web Service handler where we simply registered the handler, MVC requires a RouteHandler to pick up the handler. RouteHandlers look at the URL's path and based on that decide on what handler to invoke. The route handler is pretty simple - all it does is load our custom handler: public class MvcStaThreadRouteHandler : IRouteHandler { public IHttpHandler GetHttpHandler(RequestContext requestContext) { if (requestContext == null) throw new ArgumentNullException("requestContext"); return new MvcStaThreadHttpAsyncHandler(requestContext); } } At this point you can instantiate this route handler and force STA requests to MVC by specifying a route. The following sets up the ASP.NET Default Route:Route mvcRoute = new Route("{controller}/{action}/{id}", new RouteValueDictionary( new { controller = "Home", action = "Index", id = UrlParameter.Optional }), new MvcStaThreadRouteHandler()); RouteTable.Routes.Add(mvcRoute);   To make this code a little easier to work with and mimic the behavior of the routes.MapRoute() functionality extension method that MVC provides, here is an extension method for MapMvcStaRoute(): public static class RouteCollectionExtensions { public static void MapMvcStaRoute(this RouteCollection routeTable, string name, string url, object defaults = null) { Route mvcRoute = new Route(url, new RouteValueDictionary(defaults), new MvcStaThreadRouteHandler()); RouteTable.Routes.Add(mvcRoute); } } With this the syntax to add  route becomes a little easier and matches the MapRoute() method:RouteTable.Routes.MapMvcStaRoute( name: "Default", url: "{controller}/{action}/{id}", defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional } ); The nice thing about this route handler, STA Handler and extension method is that it's fully self contained. You can put all three into a single class file and stick it into your Web app, and then simply call MapMvcStaRoute() and it just works. Easy! To see whether this works create an MVC controller like this: public class ThreadTestController : Controller { public string ThreadingMode() { return Thread.CurrentThread.GetApartmentState().ToString(); } } Try this test both with only the MapRoute() hookup in the RouteConfiguration in which case you should get MTA as the value. Then change the MapRoute() call to MapMvcStaRoute() leaving all the parameters the same and re-run the request. You now should see STA as the result. You're on your way using STA COM components reliably in ASP.NET MVC. WCF Web Services running through IIS WCF Web Services provide a more robust and wider range of services for Web Services. You can use WCF over HTTP, TCP, and Pipes, and WCF services support WS* secure services. There are many features in WCF that go way beyond what ASMX can do. But it's also a bit more complex than ASMX. As a basic rule if you need to serve straight SOAP Services over HTTP I 'd recommend sticking with the simpler ASMX services especially if COM is involved. If you need WS* support or want to serve data over non-HTTP protocols then WCF makes more sense. WCF is not my forte but I found a solution from Scott Seely on his blog that describes the progress and that seems to work well. I'm copying his code below so this STA information is all in one place and quickly explain. Scott's code basically works by creating a custom OperationBehavior which can be specified via an [STAOperation] attribute on every method. Using his attribute you end up with a class (or Interface if you separate the contract and class) that looks like this: [ServiceContract] public class WcfService { [OperationContract] public string HelloWorldMta() { return Thread.CurrentThread.GetApartmentState().ToString(); } // Make sure you use this custom STAOperationBehavior // attribute to force STA operation of service methods [STAOperationBehavior] [OperationContract] public string HelloWorldSta() { return Thread.CurrentThread.GetApartmentState().ToString(); } } Pretty straight forward. The latter method returns STA while the former returns MTA. To make STA work every method needs to be marked up. The implementation consists of the attribute and OperationInvoker implementation. Here are the two classes required to make this work from Scott's post:public class STAOperationBehaviorAttribute : Attribute, IOperationBehavior { public void AddBindingParameters(OperationDescription operationDescription, System.ServiceModel.Channels.BindingParameterCollection bindingParameters) { } public void ApplyClientBehavior(OperationDescription operationDescription, System.ServiceModel.Dispatcher.ClientOperation clientOperation) { // If this is applied on the client, well, it just doesn’t make sense. // Don’t throw in case this attribute was applied on the contract // instead of the implementation. } public void ApplyDispatchBehavior(OperationDescription operationDescription, System.ServiceModel.Dispatcher.DispatchOperation dispatchOperation) { // Change the IOperationInvoker for this operation. dispatchOperation.Invoker = new STAOperationInvoker(dispatchOperation.Invoker); } public void Validate(OperationDescription operationDescription) { if (operationDescription.SyncMethod == null) { throw new InvalidOperationException("The STAOperationBehaviorAttribute " + "only works for synchronous method invocations."); } } } public class STAOperationInvoker : IOperationInvoker { IOperationInvoker _innerInvoker; public STAOperationInvoker(IOperationInvoker invoker) { _innerInvoker = invoker; } public object[] AllocateInputs() { return _innerInvoker.AllocateInputs(); } public object Invoke(object instance, object[] inputs, out object[] outputs) { // Create a new, STA thread object[] staOutputs = null; object retval = null; Thread thread = new Thread( delegate() { retval = _innerInvoker.Invoke(instance, inputs, out staOutputs); }); thread.SetApartmentState(ApartmentState.STA); thread.Start(); thread.Join(); outputs = staOutputs; return retval; } public IAsyncResult InvokeBegin(object instance, object[] inputs, AsyncCallback callback, object state) { // We don’t handle async… throw new NotImplementedException(); } public object InvokeEnd(object instance, out object[] outputs, IAsyncResult result) { // We don’t handle async… throw new NotImplementedException(); } public bool IsSynchronous { get { return true; } } } The key in this setup is the Invoker and the Invoke method which creates a new thread and then fires the request on this new thread. Because this approach creates a new thread for every request it's not super efficient. There's a bunch of overhead involved in creating the thread and throwing it away after each thread, but it'll work for low volume requests and insure each thread runs in STA mode. If better performance is required it would be useful to create a custom thread manager that can pool a number of STA threads and hand off threads as needed rather than creating new threads on every request. If your Web Service needs are simple and you need only to serve standard SOAP 1.x requests, I would recommend sticking with ASMX services. It's easier to set up and work with and for STA component use it'll be significantly better performing since ASP.NET manages the STA thread pool for you rather than firing new threads for each request. One nice thing about Scotts code is though that it works in any WCF environment including self hosting. It has no dependency on ASP.NET or WebForms for that matter. STA - If you must STA components are a  pain in the ass and thankfully there isn't too much stuff out there anymore that requires it. But when you need it and you need to access STA functionality from .NET at least there are a few options available to make it happen. Each of these solutions is a bit hacky, but they work - I've used all of them in production with good results with FoxPro components. I hope compiling all of these in one place here makes it STA consumption a little bit easier. I feel your pain :-) Resources Download STA Handler Code Examples Scott Seely's original STA WCF OperationBehavior Article© Rick Strahl, West Wind Technologies, 2005-2012Posted in FoxPro   ASP.NET  .NET  COM   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Use Extension method to write cleaner code

  - by Fredrik N

  This blog post will show you step by step to refactoring some code to be more readable (at least what I think). Patrik Löwnedahl gave me some of the ideas when we where talking about making code much cleaner. The following is an simple application that will have a list of movies (Normal and Transfer). The task of the application is to calculate the total sum of each movie and also display the price of each movie. class Program { enum MovieType { Normal, Transfer } static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfNormalMovie = 0; int totalPriceOfTransferMovie = 0; foreach (var movie in movies) { if (movie == MovieType.Normal) { totalPriceOfNormalMovie += 2; Console.WriteLine("$2"); } else if (movie == MovieType.Transfer) { totalPriceOfTransferMovie += 3; Console.WriteLine("$3"); } } } private static IEnumerable<MovieType> GetMovies() { return new List<MovieType>() { MovieType.Normal, MovieType.Transfer, MovieType.Normal }; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } In the code above I’m using an enum, a good way to add types (isn’t it ;)). I also use one foreach loop to calculate the price, the loop has a condition statement to check what kind of movie is added to the list of movies. I want to reuse the foreach only to increase performance and let it do two things (isn’t that smart of me?! ;)). First of all I can admit, I’m not a big fan of enum. Enum often results in ugly condition statements and can be hard to maintain (if a new type is added we need to check all the code in our app to see if we use the enum somewhere else). I don’t often care about pre-optimizations when it comes to write code (of course I have performance in mind). I rather prefer to use two foreach to let them do one things instead of two. So based on what I don’t like and Martin Fowler’s Refactoring catalog, I’m going to refactoring this code to what I will call a more elegant and cleaner code. First of all I’m going to use Split Loop to make sure the foreach will do one thing not two, it will results in two foreach (Don’t care about performance here, if the results will results in bad performance, you can refactoring later, but computers are so fast to day, so iterating through a list is not often so time consuming.) Note: The foreach actually do four things, will come to is later. var movies = GetMovies(); int totalPriceOfNormalMovie = 0; int totalPriceOfTransferMovie = 0; foreach (var movie in movies) { if (movie == MovieType.Normal) { totalPriceOfNormalMovie += 2; Console.WriteLine("$2"); } } foreach (var movie in movies) { if (movie == MovieType.Transfer) { totalPriceOfTransferMovie += 3; Console.WriteLine("$3"); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To remove the condition statement we can use the Where extension method added to the IEnumerable<T> and is located in the System.Linq namespace: foreach (var movie in movies.Where( m => m == MovieType.Normal)) { totalPriceOfNormalMovie += 2; Console.WriteLine("$2"); } foreach (var movie in movies.Where( m => m == MovieType.Transfer)) { totalPriceOfTransferMovie += 3; Console.WriteLine("$3"); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The above code will still do two things, calculate the total price, and display the price of the movie. I will not take care of it at the moment, instead I will focus on the enum and try to remove them. One way to remove enum is by using the Replace Conditional with Polymorphism. So I will create two classes, one base class called Movie, and one called MovieTransfer. The Movie class will have a property called Price, the Movie will now hold the price:   public class Movie { public virtual int Price { get { return 2; } } } public class MovieTransfer : Movie { public override int Price { get { return 3; } } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The following code has no enum and will use the new Movie classes instead: class Program { static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfNormalMovie = 0; int totalPriceOfTransferMovie = 0; foreach (var movie in movies.Where( m => m is Movie)) { totalPriceOfNormalMovie += movie.Price; Console.WriteLine(movie.Price); } foreach (var movie in movies.Where( m => m is MovieTransfer)) { totalPriceOfTransferMovie += movie.Price; Console.WriteLine(movie.Price); } } private static IEnumerable<Movie> GetMovies() { return new List<Movie>() { new Movie(), new MovieTransfer(), new Movie() }; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   If you take a look at the foreach now, you can see it still actually do two things, calculate the price and display the price. We can do some more refactoring here by using the Sum extension method to calculate the total price of the movies:   static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfNormalMovie = movies.Where(m => m is Movie) .Sum(m => m.Price); int totalPriceOfTransferMovie = movies.Where(m => m is MovieTransfer) .Sum(m => m.Price); foreach (var movie in movies.Where( m => m is Movie)) Console.WriteLine(movie.Price); foreach (var movie in movies.Where( m => m is MovieTransfer)) Console.WriteLine(movie.Price); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now when the Movie object will hold the price, there is no need to use two separate foreach to display the price of the movies in the list, so we can use only one instead: foreach (var movie in movies) Console.WriteLine(movie.Price); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If we want to increase the Maintainability index we can use the Extract Method to move the Sum of the prices into two separate methods. The name of the method will explain what we are doing: static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfMovie = TotalPriceOfMovie(movies); int totalPriceOfTransferMovie = TotalPriceOfMovieTransfer(movies); foreach (var movie in movies) Console.WriteLine(movie.Price); } private static int TotalPriceOfMovieTransfer(IEnumerable<Movie> movies) { return movies.Where(m => m is MovieTransfer) .Sum(m => m.Price); } private static int TotalPriceOfMovie(IEnumerable<Movie> movies) { return movies.Where(m => m is Movie) .Sum(m => m.Price); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now to the last thing, I love the ForEach method of the List<T>, but the IEnumerable<T> doesn’t have it, so I created my own ForEach extension, here is the code of the ForEach extension method: public static class LoopExtensions { public static void ForEach<T>(this IEnumerable<T> values, Action<T> action) { Contract.Requires(values != null); Contract.Requires(action != null); foreach (var v in values) action(v); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } I will now replace the foreach by using this ForEach method: static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfMovie = TotalPriceOfMovie(movies); int totalPriceOfTransferMovie = TotalPriceOfMovieTransfer(movies); movies.ForEach(m => Console.WriteLine(m.Price)); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The ForEach on the movies will now display the price of the movie, but maybe we want to display the name of the movie etc, so we can use Extract Method by moving the lamdba expression into a method instead, and let the method explains what we are displaying: movies.ForEach(DisplayMovieInfo); private static void DisplayMovieInfo(Movie movie) { Console.WriteLine(movie.Price); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now the refactoring is done! Here is the complete code:   class Program { static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfMovie = TotalPriceOfMovie(movies); int totalPriceOfTransferMovie = TotalPriceOfMovieTransfer(movies); movies.ForEach(DisplayMovieInfo); } private static void DisplayMovieInfo(Movie movie) { Console.WriteLine(movie.Price); } private static int TotalPriceOfMovieTransfer(IEnumerable<Movie> movies) { return movies.Where(m => m is MovieTransfer) .Sum(m => m.Price); } private static int TotalPriceOfMovie(IEnumerable<Movie> movies) { return movies.Where(m => m is Movie) .Sum(m => m.Price); } private static IEnumerable<Movie> GetMovies() { return new List<Movie>() { new Movie(), new MovieTransfer(), new Movie() }; } } public class Movie { public virtual int Price { get { return 2; } } } public class MovieTransfer : Movie { public override int Price { get { return 3; } } } pulbic static class LoopExtensions { public static void ForEach<T>(this IEnumerable<T> values, Action<T> action) { Contract.Requires(values != null); Contract.Requires(action != null); foreach (var v in values) action(v); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } I think the new code is much cleaner than the first one, and I love the ForEach extension on the IEnumerable<T>, I can use it for different kind of things, for example: movies.Where(m => m is Movie) .ForEach(DoSomething); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } By using the Where and ForEach extension method, some if statements can be removed and will make the code much cleaner. But the beauty is in the eye of the beholder. What would you have done different, what do you think will make the first example in the blog post look much cleaner than my results, comments are welcome! If you want to know when I will publish a new blog post, you can follow me on twitter: http://www.twitter.com/fredrikn

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• Using a WCF Message Inspector to extend AppFabric Monitoring

  - by Shawn Cicoria

  I read through Ron Jacobs post on Monitoring WCF Data Services with AppFabric http://blogs.msdn.com/b/endpoint/archive/2010/06/09/tracking-wcf-data-services-with-windows-server-appfabric.aspx What is immediately striking are 2 things – it’s so easy to get monitoring data into a viewer (AppFabric Dashboard) w/ very little work.  And the 2nd thing is, why can’t this be a WCF message inspector on the dispatch side. So, I took the base class WCFUserEventProvider that’s located in the WCF/WF samples [1] in the following path, \WF_WCF_Samples\WCF\Basic\Management\AnalyticTraceExtensibility\CS\WCFAnalyticTracingExtensibility\  and then created a few classes that project the injection as a IEndPointBehavior There are just 3 classes to drive injection of the inspector at runtime via config: IDispatchMessageInspector implementation BehaviorExtensionElement implementation IEndpointBehavior implementation The full source code is below with a link to the solution file here: [Solution File] using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.ServiceModel.Dispatcher; using System.ServiceModel.Channels; using System.ServiceModel; using System.ServiceModel.Configuration; using System.ServiceModel.Description; using Microsoft.Samples.WCFAnalyticTracingExtensibility; namespace Fabrikam.Services { public class AppFabricE2EInspector : IDispatchMessageInspector { static WCFUserEventProvider evntProvider = null; static AppFabricE2EInspector() { evntProvider = new WCFUserEventProvider(); } public object AfterReceiveRequest( ref Message request, IClientChannel channel, InstanceContext instanceContext) { OperationContext ctx = OperationContext.Current; var opName = ctx.IncomingMessageHeaders.Action; evntProvider.WriteInformationEvent("start", string.Format("operation: {0} at address {1}", opName, ctx.EndpointDispatcher.EndpointAddress)); return null; } public void BeforeSendReply(ref System.ServiceModel.Channels.Message reply, object correlationState) { OperationContext ctx = OperationContext.Current; var opName = ctx.IncomingMessageHeaders.Action; evntProvider.WriteInformationEvent("end", string.Format("operation: {0} at address {1}", opName, ctx.EndpointDispatcher.EndpointAddress)); } } public class AppFabricE2EBehaviorElement : BehaviorExtensionElement { #region BehaviorExtensionElement /// <summary> /// Gets the type of behavior. /// </summary> /// <value></value> /// <returns>The type that implements the end point behavior<see cref="T:System.Type"/>.</returns> public override Type BehaviorType { get { return typeof(AppFabricE2EEndpointBehavior); } } /// <summary> /// Creates a behavior extension based on the current configuration settings. /// </summary> /// <returns>The behavior extension.</returns> protected override object CreateBehavior() { return new AppFabricE2EEndpointBehavior(); } #endregion BehaviorExtensionElement } public class AppFabricE2EEndpointBehavior : IEndpointBehavior //, IServiceBehavior { #region IEndpointBehavior public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters) {} public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime) { throw new NotImplementedException(); } public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher) { endpointDispatcher.DispatchRuntime.MessageInspectors.Add(new AppFabricE2EInspector()); } public void Validate(ServiceEndpoint endpoint) { ; } #endregion IEndpointBehavior } }     [1] http://www.microsoft.com/downloads/details.aspx?FamilyID=35ec8682-d5fd-4bc3-a51a-d8ad115a8792&displaylang=en

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• Syncing Data with a Server using Silverlight and HTTP Polling Duplex

  - by dwahlin

  Many applications have the need to stay in-sync with data provided by a service. Although web applications typically rely on standard polling techniques to check if data has changed, Silverlight provides several interesting options for keeping an application in-sync that rely on server “push” technologies. A few years back I wrote several blog posts covering different “push” technologies available in Silverlight that rely on sockets or HTTP Polling Duplex. We recently had a project that looked like it could benefit from pushing data from a server to one or more clients so I thought I’d revisit the subject and provide some updates to the original code posted. If you’ve worked with AJAX before in Web applications then you know that until browsers fully support web sockets or other duplex (bi-directional communication) technologies that it’s difficult to keep applications in-sync with a server without relying on polling. The problem with polling is that you have to check for changes on the server on a timed-basis which can often be wasteful and take up unnecessary resources. With server “push” technologies, data can be pushed from the server to the client as it changes. Once the data is received, the client can update the user interface as appropriate. Using “push” technologies allows the client to listen for changes from the data but stay 100% focused on client activities as opposed to worrying about polling and asking the server if anything has changed. Silverlight provides several options for pushing data from a server to a client including sockets, TCP bindings and HTTP Polling Duplex.  Each has its own strengths and weaknesses as far as performance and setup work with HTTP Polling Duplex arguably being the easiest to setup and get going.  In this article I’ll demonstrate how HTTP Polling Duplex can be used in Silverlight 4 applications to push data and show how you can create a WCF server that provides an HTTP Polling Duplex binding that a Silverlight client can consume.   What is HTTP Polling Duplex? Technologies that allow data to be pushed from a server to a client rely on duplex functionality. Duplex (or bi-directional) communication allows data to be passed in both directions.  A client can call a service and the server can call the client. HTTP Polling Duplex (as its name implies) allows a server to communicate with a client without forcing the client to constantly poll the server. It has the benefit of being able to run on port 80 making setup a breeze compared to the other options which require specific ports to be used and cross-domain policy files to be exposed on port 943 (as with sockets and TCP bindings). Having said that, if you’re looking for the best speed possible then sockets and TCP bindings are the way to go. But, they’re not the only game in town when it comes to duplex communication. The first time I heard about HTTP Polling Duplex (initially available in Silverlight 2) I wasn’t exactly sure how it was any better than standard polling used in AJAX applications. I read the Silverlight SDK, looked at various resources and generally found the following definition unhelpful as far as understanding the actual benefits that HTTP Polling Duplex provided: "The Silverlight client periodically polls the service on the network layer, and checks for any new messages that the service wants to send on the callback channel. The service queues all messages sent on the client callback channel and delivers them to the client when the client polls the service." Although the previous definition explained the overall process, it sounded as if standard polling was used. Fortunately, Microsoft’s Scott Guthrie provided me with a more clear definition several years back that explains the benefits provided by HTTP Polling Duplex quite well (used with his permission): "The [HTTP Polling Duplex] duplex support does use polling in the background to implement notifications – although the way it does it is different than manual polling. It initiates a network request, and then the request is effectively “put to sleep” waiting for the server to respond (it doesn’t come back immediately). The server then keeps the connection open but not active until it has something to send back (or the connection times out after 90 seconds – at which point the duplex client will connect again and wait). This way you are avoiding hitting the server repeatedly – but still get an immediate response when there is data to send." After hearing Scott’s definition the light bulb went on and it all made sense. A client makes a request to a server to check for changes, but instead of the request returning immediately, it parks itself on the server and waits for data. It’s kind of like waiting to pick up a pizza at the store. Instead of calling the store over and over to check the status, you sit in the store and wait until the pizza (the request data) is ready. Once it’s ready you take it back home (to the client). This technique provides a lot of efficiency gains over standard polling techniques even though it does use some polling of its own as a request is initially made from a client to a server. So how do you implement HTTP Polling Duplex in your Silverlight applications? Let’s take a look at the process by starting with the server. Creating an HTTP Polling Duplex WCF Service Creating a WCF service that exposes an HTTP Polling Duplex binding is straightforward as far as coding goes. Add some one way operations into an interface, create a client callback interface and you’re ready to go. The most challenging part comes into play when configuring the service to properly support the necessary binding and that’s more of a cut and paste operation once you know the configuration code to use. To create an HTTP Polling Duplex service you’ll need to expose server-side and client-side interfaces and reference the System.ServiceModel.PollingDuplex assembly (located at C:\Program Files (x86)\Microsoft SDKs\Silverlight\v4.0\Libraries\Server on my machine) in the server project. For the demo application I upgraded a basketball simulation service to support the latest polling duplex assemblies. The service simulates a simple basketball game using a Game class and pushes information about the game such as score, fouls, shots and more to the client as the game changes over time. Before jumping too far into the game push service, it’s important to discuss two interfaces used by the service to communicate in a bi-directional manner. The first is called IGameStreamService and defines the methods/operations that the client can call on the server (see Listing 1). The second is IGameStreamClient which defines the callback methods that a server can use to communicate with a client (see Listing 2).   [ServiceContract(Namespace = "Silverlight", CallbackContract = typeof(IGameStreamClient))] public interface IGameStreamService { [OperationContract(IsOneWay = true)] void GetTeamData(); } Listing 1. The IGameStreamService interface defines server operations that can be called on the server.   [ServiceContract] public interface IGameStreamClient { [OperationContract(IsOneWay = true)] void ReceiveTeamData(List<Team> teamData); [OperationContract(IsOneWay = true, AsyncPattern=true)] IAsyncResult BeginReceiveGameData(GameData gameData, AsyncCallback callback, object state); void EndReceiveGameData(IAsyncResult result); } Listing 2. The IGameStreamClient interfaces defines client operations that a server can call.   The IGameStreamService interface is decorated with the standard ServiceContract attribute but also contains a value for the CallbackContract property.  This property is used to define the interface that the client will expose (IGameStreamClient in this example) and use to receive data pushed from the service. Notice that each OperationContract attribute in both interfaces sets the IsOneWay property to true. This means that the operation can be called and passed data as appropriate, however, no data will be passed back. Instead, data will be pushed back to the client as it’s available.  Looking through the IGameStreamService interface you can see that the client can request team data whereas the IGameStreamClient interface allows team and game data to be received by the client. One interesting point about the IGameStreamClient interface is the inclusion of the AsyncPattern property on the BeginReceiveGameData operation. I initially created this operation as a standard one way operation and it worked most of the time. However, as I disconnected clients and reconnected new ones game data wasn’t being passed properly. After researching the problem more I realized that because the service could take up to 7 seconds to return game data, things were getting hung up. By setting the AsyncPattern property to true on the BeginReceivedGameData operation and providing a corresponding EndReceiveGameData operation I was able to get around this problem and get everything running properly. I’ll provide more details on the implementation of these two methods later in this post. Once the interfaces were created I moved on to the game service class. The first order of business was to create a class that implemented the IGameStreamService interface. Since the service can be used by multiple clients wanting game data I added the ServiceBehavior attribute to the class definition so that I could set its InstanceContextMode to InstanceContextMode.Single (in effect creating a Singleton service object). Listing 3 shows the game service class as well as its fields and constructor.   [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.Single)] public class GameStreamService : IGameStreamService { object _Key = new object(); Game _Game = null; Timer _Timer = null; Random _Random = null; Dictionary<string, IGameStreamClient> _ClientCallbacks = new Dictionary<string, IGameStreamClient>(); static AsyncCallback _ReceiveGameDataCompleted = new AsyncCallback(ReceiveGameDataCompleted); public GameStreamService() { _Game = new Game(); _Timer = new Timer { Enabled = false, Interval = 2000, AutoReset = true }; _Timer.Elapsed += new ElapsedEventHandler(_Timer_Elapsed); _Timer.Start(); _Random = new Random(); }} Listing 3. The GameStreamService implements the IGameStreamService interface which defines a callback contract that allows the service class to push data back to the client. By implementing the IGameStreamService interface, GameStreamService must supply a GetTeamData() method which is responsible for supplying information about the teams that are playing as well as individual players.  GetTeamData() also acts as a client subscription method that tracks clients wanting to receive game data.  Listing 4 shows the GetTeamData() method. public void GetTeamData() { //Get client callback channel var context = OperationContext.Current; var sessionID = context.SessionId; var currClient = context.GetCallbackChannel<IGameStreamClient>(); context.Channel.Faulted += Disconnect; context.Channel.Closed += Disconnect; IGameStreamClient client; if (!_ClientCallbacks.TryGetValue(sessionID, out client)) { lock (_Key) { _ClientCallbacks[sessionID] = currClient; } } currClient.ReceiveTeamData(_Game.GetTeamData()); //Start timer which when fired sends updated score information to client if (!_Timer.Enabled) { _Timer.Enabled = true; } } Listing 4. The GetTeamData() method subscribes a given client to the game service and returns. The key the line of code in the GetTeamData() method is the call to GetCallbackChannel<IGameStreamClient>().  This method is responsible for accessing the calling client’s callback channel. The callback channel is defined by the IGameStreamClient interface shown earlier in Listing 2 and used by the server to communicate with the client. Before passing team data back to the client, GetTeamData() grabs the client’s session ID and checks if it already exists in the _ClientCallbacks dictionary object used to track clients wanting callbacks from the server. If the client doesn’t exist it adds it into the collection. It then pushes team data from the Game class back to the client by calling ReceiveTeamData().  Since the service simulates a basketball game, a timer is then started if it’s not already enabled which is then used to randomly send data to the client. When the timer fires, game data is pushed down to the client. Listing 5 shows the _Timer_Elapsed() method that is called when the timer fires as well as the SendGameData() method used to send data to the client. void _Timer_Elapsed(object sender, ElapsedEventArgs e) { int interval = _Random.Next(3000, 7000); lock (_Key) { _Timer.Interval = interval; _Timer.Enabled = false; } SendGameData(_Game.GetGameData()); } private void SendGameData(GameData gameData) { var cbs = _ClientCallbacks.Where(cb => ((IContextChannel)cb.Value).State == CommunicationState.Opened); for (int i = 0; i < cbs.Count(); i++) { var cb = cbs.ElementAt(i).Value; try { cb.BeginReceiveGameData(gameData, _ReceiveGameDataCompleted, cb); } catch (TimeoutException texp) { //Log timeout error } catch (CommunicationException cexp) { //Log communication error } } lock (_Key) _Timer.Enabled = true; } private static void ReceiveGameDataCompleted(IAsyncResult result) { try { ((IGameStreamClient)(result.AsyncState)).EndReceiveGameData(result); } catch (CommunicationException) { // empty } catch (TimeoutException) { // empty } } LIsting 5. _Timer_Elapsed is used to simulate time in a basketball game. When _Timer_Elapsed() fires the SendGameData() method is called which iterates through the clients wanting to be notified of changes. As each client is identified, their respective BeginReceiveGameData() method is called which ultimately pushes game data down to the client. Recall that this method was defined in the client callback interface named IGameStreamClient shown earlier in Listing 2. Notice that BeginReceiveGameData() accepts _ReceiveGameDataCompleted as its second parameter (an AsyncCallback delegate defined in the service class) and passes the client callback as the third parameter. The initial version of the sample application had a standard ReceiveGameData() method in the client callback interface. However, sometimes the client callbacks would work properly and sometimes they wouldn’t which was a little baffling at first glance. After some investigation I realized that I needed to implement an asynchronous pattern for client callbacks to work properly since 3 – 7 second delays are occurring as a result of the timer. Once I added the BeginReceiveGameData() and ReceiveGameDataCompleted() methods everything worked properly since each call was handled in an asynchronous manner. The final task that had to be completed to get the server working properly with HTTP Polling Duplex was adding configuration code into web.config. In the interest of brevity I won’t post all of the code here since the sample application includes everything you need. However, Listing 6 shows the key configuration code to handle creating a custom binding named pollingDuplexBinding and associate it with the service’s endpoint.   <bindings> <customBinding> <binding name="pollingDuplexBinding"> <binaryMessageEncoding /> <pollingDuplex maxPendingSessions="2147483647" maxPendingMessagesPerSession="2147483647" inactivityTimeout="02:00:00" serverPollTimeout="00:05:00"/> <httpTransport /> </binding> </customBinding> </bindings> <services> <service name="GameService.GameStreamService" behaviorConfiguration="GameStreamServiceBehavior"> <endpoint address="" binding="customBinding" bindingConfiguration="pollingDuplexBinding" contract="GameService.IGameStreamService"/> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services>   Listing 6. Configuring an HTTP Polling Duplex binding in web.config and associating an endpoint with it. Calling the Service and Receiving “Pushed” Data Calling the service and handling data that is pushed from the server is a simple and straightforward process in Silverlight. Since the service is configured with a MEX endpoint and exposes a WSDL file, you can right-click on the Silverlight project and select the standard Add Service Reference item. After the web service proxy is created you may notice that the ServiceReferences.ClientConfig file only contains an empty configuration element instead of the normal configuration elements created when creating a standard WCF proxy. You can certainly update the file if you want to read from it at runtime but for the sample application I fed the service URI directly to the service proxy as shown next: var address = new EndpointAddress("http://localhost.:5661/GameStreamService.svc"); var binding = new PollingDuplexHttpBinding(); _Proxy = new GameStreamServiceClient(binding, address); _Proxy.ReceiveTeamDataReceived += _Proxy_ReceiveTeamDataReceived; _Proxy.ReceiveGameDataReceived += _Proxy_ReceiveGameDataReceived; _Proxy.GetTeamDataAsync(); This code creates the proxy and passes the endpoint address and binding to use to its constructor. It then wires the different receive events to callback methods and calls GetTeamDataAsync().  Calling GetTeamDataAsync() causes the server to store the client in the server-side dictionary collection mentioned earlier so that it can receive data that is pushed.  As the server-side timer fires and game data is pushed to the client, the user interface is updated as shown in Listing 7. Listing 8 shows the _Proxy_ReceiveGameDataReceived() method responsible for handling the data and calling UpdateGameData() to process it.   Listing 7. The Silverlight interface. Game data is pushed from the server to the client using HTTP Polling Duplex. void _Proxy_ReceiveGameDataReceived(object sender, ReceiveGameDataReceivedEventArgs e) { UpdateGameData(e.gameData); } private void UpdateGameData(GameData gameData) { //Update Score this.tbTeam1Score.Text = gameData.Team1Score.ToString(); this.tbTeam2Score.Text = gameData.Team2Score.ToString(); //Update ball visibility if (gameData.Action != ActionsEnum.Foul) { if (tbTeam1.Text == gameData.TeamOnOffense) { AnimateBall(this.BB1, this.BB2); } else //Team 2 { AnimateBall(this.BB2, this.BB1); } } if (this.lbActions.Items.Count > 9) this.lbActions.Items.Clear(); this.lbActions.Items.Add(gameData.LastAction); if (this.lbActions.Visibility == Visibility.Collapsed) this.lbActions.Visibility = Visibility.Visible; } private void AnimateBall(Image onBall, Image offBall) { this.FadeIn.Stop(); Storyboard.SetTarget(this.FadeInAnimation, onBall); Storyboard.SetTarget(this.FadeOutAnimation, offBall); this.FadeIn.Begin(); } Listing 8. As the server pushes game data, the client’s _Proxy_ReceiveGameDataReceived() method is called to process the data. In a real-life application I’d go with a ViewModel class to handle retrieving team data, setup data bindings and handle data that is pushed from the server. However, for the sample application I wanted to focus on HTTP Polling Duplex and keep things as simple as possible.   Summary Silverlight supports three options when duplex communication is required in an application including TCP bindins, sockets and HTTP Polling Duplex. In this post you’ve seen how HTTP Polling Duplex interfaces can be created and implemented on the server as well as how they can be consumed by a Silverlight client. HTTP Polling Duplex provides a nice way to “push” data from a server while still allowing the data to flow over port 80 or another port of your choice.   Sample Application Download

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• ASP.NET ViewState Tips and Tricks #2

  - by João Angelo

  If you need to store complex types in ViewState DO implement IStateManager to control view state persistence and reduce its size. By default a serializable object will be fully stored in view state using BinaryFormatter. A quick comparison for a complex type with two integers and one string property produces the following results measured using ASP.NET tracing: BinaryFormatter: 328 bytes in view state IStateManager: 28 bytes in view state BinaryFormatter sample code: // DO NOT [Serializable] public class Info { public int Id { get; set; } public string Name { get; set; } public int Age { get; set; } } public class ExampleControl : WebControl { protected override void OnLoad(EventArgs e) { base.OnLoad(e); if (!this.Page.IsPostBack) { this.User = new Info { Id = 1, Name = "John Doe", Age = 27 }; } } public Info User { get { object o = this.ViewState["Example_User"]; if (o == null) return null; return (Info)o; } set { this.ViewState["Example_User"] = value; } } } IStateManager sample code: // DO public class Info : IStateManager { public int Id { get; set; } public string Name { get; set; } public int Age { get; set; } private bool isTrackingViewState; bool IStateManager.IsTrackingViewState { get { return this.isTrackingViewState; } } void IStateManager.LoadViewState(object state) { var triplet = (Triplet)state; this.Id = (int)triplet.First; this.Name = (string)triplet.Second; this.Age = (int)triplet.Third; } object IStateManager.SaveViewState() { return new Triplet(this.Id, this.Name, this.Age); } void IStateManager.TrackViewState() { this.isTrackingViewState = true; } } public class ExampleControl : WebControl { protected override void OnLoad(EventArgs e) { base.OnLoad(e); if (!this.Page.IsPostBack) { this.User = new Info { Id = 1, Name = "John Doe", Age = 27 }; } } public Info User { get; set; } protected override object SaveViewState() { return new Pair( ((IStateManager)this.User).SaveViewState(), base.SaveViewState()); } protected override void LoadViewState(object savedState) { if (savedState != null) { var pair = (Pair)savedState; this.User = new Info(); ((IStateManager)this.User).LoadViewState(pair.First); base.LoadViewState(pair.Second); } } }

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• Subterranean IL: Volatile

  - by Simon Cooper

  This time, we'll be having a look at the volatile. prefix instruction, and one of the differences between volatile in IL and C#. The volatile. prefix volatile is a tricky one, as there's varying levels of documentation on it. From what I can see, it has two effects: It prevents caching of the load or store value; rather than reading or writing to a cached version of the memory location (say, the processor register or cache), it forces the value to be loaded or stored at the 'actual' memory location, so it is then immediately visible to other threads. It forces a memory barrier at the prefixed instruction. This ensures instructions don't get re-ordered around the volatile instruction. This is slightly more complicated than it first seems, and only seems to matter on certain architectures. For more details, Joe Duffy has a blog post going into the details. For this post, I'll be concentrating on the first aspect of volatile. Caching field accesses To demonstrate this, I created a simple multithreaded IL program. It boils down to the following code: .class public Holder { .field public static class Holder holder .field public bool stop .method public static specialname void .cctor() { newobj instance void Holder::.ctor() stsfld class Holder Holder::holder ret }}.method private static void Main() { .entrypoint // Thread t = new Thread(new ThreadStart(DoWork)) // t.Start() // Thread.Sleep(2000) // Console.WriteLine("Stopping thread...") ldsfld class Holder Holder::holder ldc.i4.1 stfld bool Holder::stop call instance void [mscorlib]System.Threading.Thread::Join() ret}.method private static void DoWork() { ldsfld class Holder Holder::holder // while (!Holder.holder.stop) {} DoWork: dup ldfld bool Holder::stop brfalse DoWork pop ret} If you compile and run this code, you'll find that the call to Thread.Join() never returns - the DoWork spinlock is reading a cached version of Holder.stop, which is never being updated with the new value set by the Main method. Adding volatile to the ldfld fixes this: dupvolatile.ldfld bool Holder::stopbrfalse DoWork The volatile ldfld forces the field access to read direct from heap memory, which is then updated by the main thread, rather than using a cached copy. volatile in C# This highlights one of the differences between IL and C#. In IL, volatile only applies to the prefixed instruction, whereas in C#, volatile is specified on a field to indicate that all accesses to that field should be volatile (interestingly, there's no mention of the 'no caching' aspect of volatile in the C# spec; it only focuses on the memory barrier aspect). Furthermore, this information needs to be stored within the assembly somehow, as such a field might be accessed directly from outside the assembly, but there's no concept of a 'volatile field' in IL! How this information is stored with the field will be the subject of my next post.

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• Base Pages and Interfaces for ASP.NET Pages

  - by geekrutherford

  For quite a while I have been using the concept of base pages when developing pages in ASP.NET applications. It is a wonderful method for exposing common functions to all of your applications pages and also overriding certain events for various purposes (i.e. dynamic themes).  Recently I found out a new developer will be joining my team. This prompted me to review the applications code for readability and ease of maintenance. I began adding comments through out the code behind for all pages within the application. While doing so I noted that I had used common method names for such things as loading data, configuring controls, applying filters, etc.   Bringing a new developer on board, I wanted to make the transition as seamless as possible while also ensuring they follow existing coding practices we already have in place. While I could have created virtual methods for the common page methods allowing them to overridden, what I really needed was a way to ensure the new developer implemented the same methods for each and every page. Thus I created an interface to force the issue.   Now, every page not only inherits the base page class but also implements an interface. This provides every page not only common functions and overridden page events but also imposes rules for implementing certain common methods :-)   Interface   public interface BasePageInterface { /// Configures page based on users security permissions. void CheckPermissions(); /// Configures Filter Form control for current page.  /// Ensure you have set the FilteredGrid and PageAjaxManager properties of the FilterForm control in PageLoad!!!  void ConfigureFilters(); /// Sets event handlers and default settings for controls on the current page. void ConfigureControls(); /// Exports data bound to grid in selected format. void ExportGridData(ExportFormat fmt); /// Loads data and binds to grid. /// Columns are turned on/off in grid depending on tab selected and users permissions.  void LoadData(); }   Page code-behind class definition:   public partial class MyPage : BasePage, BasePageInterface Note, you could not use an abstract class to accomplish this considering C# does not allow for multiple inheritance.  Nor could the base page class be abstract since it needs to inherit from the System.Web.UI.Page class in order to override page events.

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• How do I make this rendering thread run together with the main one?

  - by funk

  I'm developing an Android game and need to show an animation of an exploding bomb. It's a spritesheet with 1 row and 13 different images. Each image should be displayed in sequence, 200 ms apart. There is one Thread running for the entire game: package com.android.testgame; import android.graphics.Canvas; public class GameLoopThread extends Thread { static final long FPS = 10; // 10 Frames per Second private final GameView view; private boolean running = false; public GameLoopThread(GameView view) { this.view = view; } public void setRunning(boolean run) { running = run; } @Override public void run() { long ticksPS = 1000 / FPS; long startTime; long sleepTime; while (running) { Canvas c = null; startTime = System.currentTimeMillis(); try { c = view.getHolder().lockCanvas(); synchronized (view.getHolder()) { view.onDraw(c); } } finally { if (c != null) { view.getHolder().unlockCanvasAndPost(c); } } sleepTime = ticksPS - (System.currentTimeMillis() - startTime); try { if (sleepTime > 0) { sleep(sleepTime); } else { sleep(10); } } catch (Exception e) {} } } } As far as I know I would have to create a second Thread for the bomb. package com.android.testgame; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Rect; public class Bomb { private final Bitmap bmp; private final int width; private final int height; private int currentFrame = 0; private static final int BMPROWS = 1; private static final int BMPCOLUMNS = 13; private int x = 0; private int y = 0; public Bomb(GameView gameView, Bitmap bmp) { this.width = bmp.getWidth() / BMPCOLUMNS; this.height = bmp.getHeight() / BMPROWS; this.bmp = bmp; x = 250; y = 250; } private void update() { currentFrame++; new BombThread().start(); } public void onDraw(Canvas canvas) { update(); int srcX = currentFrame * width; int srcY = height; Rect src = new Rect(srcX, srcY, srcX + width, srcY + height); Rect dst = new Rect(x, y, x + width, y + height); canvas.drawBitmap(bmp, src, dst, null); } class BombThread extends Thread { @Override public void run() { try { sleep(200); } catch(InterruptedException e){ } } } } The Threads would then have to run simultaneously. How do I do this?

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• Nifty popup fails to register

  - by Snailer

  I'm new to Nifty GUI, so I'm following a tutorial here for making popups. For now, I'm just trying to get a very basic "test" popup to show, but I get multiple errors and none of them make much sense. To show a popup, I believe it is necessary to first have a Nifty Screen already showing, which I do. So here is the ScreenController for the working Nifty Screen: public class WorkingScreen extends AbstractAppState implements ScreenController { //Main is my jme SimpleApplication private Main app; private Nifty nifty; private Screen screen; public WorkingScreen() {} public void equip(String slotstr) { int slot = Integer.valueOf(slotstr); System.out.println("Equipping item in slot "+slot); //Here's where it STOPS working. app.getPlayer().registerPopupScreen(nifty); System.out.println("Registered new popup"); Element ele = nifty.createPopup(app.getPlayer().POPUP); System.out.println("popup is " +ele); nifty.showPopup(nifty.getCurrentScreen(), ele.getId(), null); } @Override public void initialize(AppStateManager stateManager, Application app) { super.initialize(stateManager, app); this.app = (Main)app; } @Override public void update(float tpf) { /** jME update loop! */ } public void bind(Nifty nifty, Screen screen) { this.nifty = nifty; this.screen = screen; } When I call equip(0) the system prints Equipping item in slot 0, then a lot of errors and none of the subsequent println()'s. Clearly it botches somewhere in Player.registerPopupScreen(Nifty nifty). Here's the method: public final String POPUP = "Test Popup"; public void registerPopupScreen(Nifty nifty) { System.out.println("Attempting new popup"); PopupBuilder b = new PopupBuilder(POPUP) {{ childLayoutCenter(); backgroundColor("#000a"); panel(new PanelBuilder() {{ id("List"); childLayoutCenter(); height(percentage(75)); width(percentage(50)); control(new ButtonBuilder("TestButton") {{ label("TestButton"); width("120px"); height("40px"); align(Align.Center); }}); }}); }}; System.out.println("PopupBuilder success."); b.registerPopup(nifty); System.out.println("Registerpopup success."); } Because that first println() doesn't show, it looks like this method isn't even called at all! Edit After removing all calls on the Player object, the popup works. It seems I'm not "allowed" to access the player from the ScreenController. Unfortunate, since I need information on the player for the popup. Is there a workaround?

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• Java - Draw Cards and Eliminate Cards Problem

  - by Jen

  I am having a problem in this question. I want a system inside a game wherein the player draws 2 cards randomly, and the enemy draws 2 cards randomly. Then, what the program does is to print out to the console the cards the player draw and the enemy's. The cards should not conflict and must not be the same. Then lastly, the program prints out the card that was not drawn by both the player and the enemy. Here's how I did it but it was lengthy and full of errors: import java.util.Random; public class Draw { public static Random random = new Random(); public static String cards[] = {"Hall", "Kitchen", "Billiard", "Study", "Pool"}; public static int playercounter; public static int enemycounter; public static String playercardA = null; public static String playercardB = null; public static String enemycardA = null; public static String enemycardB = null; public String lastcard = null; public static void playercardAdraw() { playercounter = random.nextInt(5); playercardA = cards[playercounter]; } public static void playercardBdraw() { playercounter=random.nextInt(5); playercardB= cards[playercounter]; if (playercardB==playercardA || playercardB == enemycardA || playercardB == enemycardB) { return; } } public static void enemycardAdraw () { enemycounter = random.nextInt(5); enemycardA=cards[enemycounter]; if (enemycardA == playercardA || enemycardA == playercardB) { return; } } public static void enemycardBdraw () { enemycounter = random.nextInt(5); enemycardB=cards[enemycounter]; if (enemycardB == playercardA || enemycardB == playercardB || enemycardB == enemycardA) { return; } } public static void main (String args []) { System.out.println("Starting to draw..."); System.out.println("Player's Turn: "); playercardAdraw(); System.out.println("Player's first card: " + playercardA); playercardBdraw(); System.out.println("Player's second card: " + playercardB); System.out.println("Enemy's Turn: "); enemycardAdraw(); System.out.println("Enemy's first card: " + enemycardA); enemycardBdraw(); System.out.println("Enemy's Second card: " + enemycardB); } }

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• Write and fprintf for file I/O

  - by Darryl Gove

  fprintf() does buffered I/O, where as write() does unbuffered I/O. So once the write() completes, the data is in the file, whereas, for fprintf() it may take a while for the file to get updated to reflect the output. This results in a significant performance difference - the write works at disk speed. The following is a program to test this: #include <fcntl.h #include <unistd.h #include <stdio.h #include <stdlib.h #include <errno.h #include <stdio.h #include <sys/time.h #include <sys/types.h #include <sys/stat.h static double s_time; void starttime() { s_time=1.0*gethrtime(); } void endtime(long its) { double e_time=1.0*gethrtime(); printf("Time per iteration %5.2f MB/s\n", (1.0*its)/(e_time-s_time*1.0)*1000); s_time=1.0*gethrtime(); } #define SIZE 10*1024*1024 void test_write() { starttime(); int file = open("./test.dat",O_WRONLY|O_CREAT,S_IWGRP|S_IWOTH|S_IWUSR); for (int i=0; i<SIZE; i++) { write(file,"a",1); } close(file); endtime(SIZE); } void test_fprintf() { starttime(); FILE* file = fopen("./test.dat","w"); for (int i=0; i<SIZE; i++) { fprintf(file,"a"); } fclose(file); endtime(SIZE); } void test_flush() { starttime(); FILE* file = fopen("./test.dat","w"); for (int i=0; i<SIZE; i++) { fprintf(file,"a"); fflush(file); } fclose(file); endtime(SIZE); } int main() { test_write(); test_fprintf(); test_flush(); } Compiling and running I get 0.2MB/s for write() and 6MB/s for fprintf(). A large difference. There's three tests in this example, the third test uses fprintf() and fflush(). This is equivalent to write() both in performance and in functionality. Which leads to the suggestion that fprintf() (and other buffering I/O functions) are the fastest way of writing to files, and that fflush() should be used to enforce synchronisation of the file contents.

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• Savable in Widget Lookup on Move Action

  - by Geertjan

  Possible from 7.3 onwards, since Widget now implements Lookup.Provider for the first time: import java.awt.Point; import java.io.IOException; import org.netbeans.api.visual.action.ActionFactory; import org.netbeans.api.visual.action.MoveProvider; import org.netbeans.api.visual.widget.LabelWidget; import org.netbeans.api.visual.widget.Scene; import org.netbeans.api.visual.widget.Widget; import org.netbeans.spi.actions.AbstractSavable; import org.openide.util.Lookup; import org.openide.util.lookup.AbstractLookup; import org.openide.util.lookup.InstanceContent; import org.openide.windows.TopComponent; public class MyWidget extends LabelWidget { private MySavable mySavable; private Lookup lookup; private TopComponent tc; private InstanceContent ic; public MyWidget(Scene scene, String label, TopComponent tc) { super(scene, label); this.tc = tc; ic = new InstanceContent(); getActions().addAction(ActionFactory.createMoveAction(null, new MoveStrategyProvider())); } @Override public Lookup getLookup() { if (lookup == null) { lookup = new AbstractLookup(ic); } return lookup; } private class MoveStrategyProvider implements MoveProvider { @Override public void movementStarted(Widget widget) { } @Override public void movementFinished(Widget widget) { modify(); } @Override public Point getOriginalLocation(Widget widget) { return ActionFactory.createDefaultMoveProvider().getOriginalLocation(widget); } @Override public void setNewLocation(Widget widget, Point point) { ActionFactory.createDefaultMoveProvider().setNewLocation(widget, point); } } private void modify() { if (getLookup().lookup(MySavable.class) == null) { ic.add(mySavable = new MySavable()); } } private class MySavable extends AbstractSavable { public MySavable() { register(); } TopComponent tc() { return tc; } @Override protected String findDisplayName() { return getLabel(); } @Override protected void handleSave() throws IOException { ic.remove(mySavable); unregister(); } @Override public boolean equals(Object obj) { if (obj instanceof MySavable) { MySavable m = (MySavable) obj; return tc() == m.tc(); } return false; } @Override public int hashCode() { return tc().hashCode(); } } }

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• Draw Cards and Eliminate Cards Problem

  - by Jen

  I am having a problem in this question. I want a system inside a game wherein the player draws 2 cards randomly, and the enemy draws 2 cards randomly. Then, what the program does is to print out to the console the cards the player draw and the enemy's. The cards should not conflict and must not be the same. Then lastly, the program prints out the card that was not drawn by both the player and the enemy. Here's how I did it but it was lengthy and full of errors: import java.util.Random; public class Draw { public static Random random = new Random(); public static String cards[] = {"Hall", "Kitchen", "Billiard", "Study", "Pool"}; public static int playercounter; public static int enemycounter; public static String playercardA = null; public static String playercardB = null; public static String enemycardA = null; public static String enemycardB = null; public String lastcard = null; public static void playercardAdraw() { playercounter = random.nextInt(5); playercardA = cards[playercounter]; } public static void playercardBdraw() { playercounter=random.nextInt(5); playercardB= cards[playercounter]; if (playercardB==playercardA || playercardB == enemycardA || playercardB == enemycardB) { return; } } public static void enemycardAdraw () { enemycounter = random.nextInt(5); enemycardA=cards[enemycounter]; if (enemycardA == playercardA || enemycardA == playercardB) { return; } } public static void enemycardBdraw () { enemycounter = random.nextInt(5); enemycardB=cards[enemycounter]; if (enemycardB == playercardA || enemycardB == playercardB || enemycardB == enemycardA) { return; } } public static void main (String args []) { System.out.println("Starting to draw..."); System.out.println("Player's Turn: "); playercardAdraw(); System.out.println("Player's first card: " + playercardA); playercardBdraw(); System.out.println("Player's second card: " + playercardB); System.out.println("Enemy's Turn: "); enemycardAdraw(); System.out.println("Enemy's first card: " + enemycardA); enemycardBdraw(); System.out.println("Enemy's Second card: " + enemycardB); } }

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• Crash when using Cocos2d

  - by ipodfreak0313

  Sorry about the poor question title, it's just that this seems to big for a title. So here's the dirt: I am making a game (obviously) and I want the enemies to shoot (not necessarily at the player). I want the shoot method to be in the Enemies file, so as not to clutter up my HelloWorldLayer.m file even more. Here's what I'm using right now: HelloWorldLayer.m -(void)addEnemy:(BigAndStrongEnemy *)enemy { enemy = nil; if((arc4random() % 4) == 3) { enemy = [BigAndStrongEnemy enemy]; } else { enemy = [SmallAndFastEnemy enemy]; } if(buffDude.position.y > character.position.y || buffDude.position.y < (character.position.y + 10)) { } int rand = arc4random() % 320; if((arc4random() % 2 == 1)) { [enemy setPosition:ccp(0,rand)]; }else{ [enemy setPosition:ccp(480,rand)]; } [self animateEnemy:enemy]; [self addChild:enemy]; } -(void)animateEnemy:(BigAndStrongEnemy *)enemy2 { float randX = arc4random() % 480; float randY = arc4random() % 320; int rand = arc4random() % 320; CGPoint moveToPoint = CGPointMake(randX, (randY - rand)); [enemies addObject:enemy2]; action = [CCSequence actions: [CCMoveBy actionWithDuration:1 position:ccpMult(ccpNormalize(ccpSub(moveToPoint, enemy2.position)), 75)], [CCMoveBy actionWithDuration:3 position:ccp(buffDude.position.x,buffDude.position.y)], nil]; CCCallFuncO *a = [CCCallFuncO actionWithTarget:self selector:(@selector(shoot:)) object:enemy2]; CCSequence *s = [CCSequence actions:action,a, nil]; CCRepeatForever *repeat = [CCRepeatForever actionWithAction:s]; [enemy2 runAction:repeat]; } And here's the Shoot info from the Enemies class: Enemies.m: -(void)shoot:(id)sender { self = (BigAndStrongEnemy *)sender; [self shoot]; } -(void)spriteMoveFinished:(id)sender { CCSprite *b = (CCSprite *)sender; [self removeChild:b cleanup:YES]; } -(void)shoot { self = [CCSprite spriteWithFile:@"bigAndStrongEnemy.gif"]; CCSprite *b = [CCSprite spriteWithFile:@"bullet.gif"]; b.position = ccp(self.position.x,self.position.y); b.tag = 2; [self addChild:b]; [bullets addObject:b]; CGSize winSize = [[CCDirector sharedDirector] winSize]; CGPoint point = CGPointMake((winSize.width - (winSize.width - self.position.x)),0); [b runAction:[CCSequence actions: [CCMoveBy actionWithDuration:0.5 position:point], [CCCallFuncN actionWithTarget:self selector:@selector(spriteMoveFinished:)], nil]]; } Every time the 3 seconds goes by, the app crashes, and goes to the breakpoint in the CCCallFuncO file. I haven't touched it, is the thing. I am completely confused. Any help is greatly appreciated.

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• Separate Action from Assertion in Unit Tests

  - by DigitalMoss

  Setup Many years ago I took to a style of unit testing that I have come to like a lot. In short, it uses a base class to separate out the Arrangement, Action and Assertion of the test into separate method calls. You do this by defining method calls in [Setup]/[TestInitialize] that will be called before each test run. [Setup] public void Setup() { before_each(); //arrangement because(); //action } This base class usually includes the [TearDown] call as well for when you are using this setup for Integration tests. [TearDown] public void Cleanup() { after_each(); } This often breaks out into a structure where the test classes inherit from a series of Given classes that put together the setup (i.e. GivenFoo : GivenBar : WhenDoingBazz) with the Assertions being one line tests with a descriptive name of what they are covering [Test] public void ThenBuzzSouldBeTrue() { Assert.IsTrue(result.Buzz); } The Problem There are very few tests that wrap around a single action so you end up with lots of classes so recently I have taken to defining the action in a series of methods within the test class itself: [Test] public void ThenBuzzSouldBeTrue() { because_an_action_was_taken(); Assert.IsTrue(result.Buzz); } private void because_an_action_was_taken() { //perform action here } This results in several "action" methods within the test class but allows grouping of similar tests (i.e. class == WhenTestingDifferentWaysToSetBuzz) The Question Does someone else have a better way of separating out the three 'A's of testing? Readability of tests is important to me so I would prefer that, when a test fails, that the very naming structure of the tests communicate what has failed. If someone can read the Inheritance structure of the tests and have a good idea why the test might be failing then I feel it adds a lot of value to the tests (i.e. GivenClient : GivenUser : WhenModifyingUserPermissions : ThenReadAccessShouldBeTrue). I am aware of Acceptance Testing but this is more on a Unit (or series of units) level with boundary layers mocked. EDIT : My question is asking if there is an event or other method for executing a block of code before individual tests (something that could be applied to specific sets of tests without it being applied to all tests within a class like [Setup] currently does. Barring the existence of this event, which I am fairly certain doesn't exist, is there another method for accomplishing the same thing? Using [Setup] for every case presents a problem either way you go. Something like [Action("Category")] (a setup method that applied to specific tests within the class) would be nice but I can't find any way of doing this.

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• Why is my primitive xna square not drawn/shown?

  - by Mech0z

  I have made this class to draw a rectangle, but I cant get it to be drawn, I have no issues displaying a 3d model created in 3dmax, but shown these primitives seems much harder I use this to create it board = new Board(Vector3.Zero, 1000, 1000, Color.Yellow); And here is the implementation 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.Shapes; using Quadro.Models; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Graphics; namespace Quadro { public class Board : IGraphicObject { //Private Fields private Vector3 modelPosition; private BasicEffect effect; private VertexPositionColor[] vertices; private Matrix rotationMatrix; private GraphicsDevice graphicsDevice; private Matrix cameraProjection; //Constructor public Board(Vector3 position, float length, float width, Color color) { var _color = color; vertices = new VertexPositionColor[6]; vertices[0].Position = new Vector3(position.X, position.Y, position.Z); vertices[1].Position = new Vector3(position.X, position.Y + width, position.Z); vertices[2].Position = new Vector3(position.X + length, position.Y, position.Z); vertices[3].Position = new Vector3(position.X + length, position.Y, position.Z); vertices[4].Position = new Vector3(position.X, position.Y + width, position.Z); vertices[5].Position = new Vector3(position.X + length, position.Y + width, position.Z); for(int i = 0; i < vertices.Length; i++) { vertices[i].Color = color; } initFields(); } private void initFields() { graphicsDevice = SharedGraphicsDeviceManager.Current.GraphicsDevice; effect = new BasicEffect(graphicsDevice); modelPosition = Vector3.Zero; float screenWidth = (float)graphicsDevice.Viewport.Width; float screenHeight = (float)graphicsDevice.Viewport.Height; float aspectRatio = screenWidth / screenHeight; this.cameraProjection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); this.rotationMatrix = Matrix.Identity; } //Public Methods public void Update(GameTimerEventArgs e) { } public void Draw(Vector3 cameraPosition, GameTimerEventArgs e) { Matrix cameraView = Matrix.CreateLookAt(cameraPosition, Vector3.Zero, Vector3.Up); foreach (EffectPass pass in effect.CurrentTechnique.Passes) { pass.Apply(); effect.World = rotationMatrix * Matrix.CreateTranslation(modelPosition); effect.View = cameraView; effect.Projection = cameraProjection; graphicsDevice.DrawUserPrimitives(PrimitiveType.TriangleList, vertices, 0, 2, VertexPositionColor.VertexDeclaration); } } public void Rotate(Matrix rotationMatrix) { this.rotationMatrix = rotationMatrix; } public void Move(Vector3 moveVector) { this.modelPosition += moveVector; } } }

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• rotating spheres

  - by Dave

  I want to continuously rotate 2 spheres, however the rotation does not seem to work. Here is my code: float angle = 0.0f; void light(){ glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); glEnable(GL_LIGHT1); // Create light components GLfloat positionlight1[] = { 9.0, 5.0, 1.0, 0.0 }; GLfloat positionlight2[] = {0.2,2.5,1.3,0.0}; GLfloat light_ambient1[] = { 0.0, 0.0, 1.0, 1.0}; GLfloat light_diffuse[] = { 1.0, 1.0, 1.0, 1.0 }; glLightfv(GL_LIGHT0, GL_AMBIENT, light_ambient1); glLightfv(GL_LIGHT1, GL_DIFFUSE, light_diffuse); glLightfv(GL_LIGHT0, GL_POSITION, positionlight1); glLightfv(GL_LIGHT1, GL_POSITION, positionlight2); } void changeSize(int w, int h) { if (h==0) // Prevent A Divide By Zero By { h=1; // Making Height Equal One } glMatrixMode(GL_PROJECTION); // Select The Projection Matrix glLoadIdentity(); // Reset The Projection Matrix glViewport(0,0,w,h);// Reset The Current Viewport // Calculate The Aspect Ratio Of The Window gluPerspective(45.0f,(GLfloat)w/(GLfloat)h,0.1f,100.0f); glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix // Reset The Modelview Matrix } void renderScene(void) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glPushMatrix(); //set where to start the current object glTranslatef(0.0,1.2,-6); glRotatef(angle,0,1.2,-6); glutSolidSphere(1,50,50); glPopMatrix(); //end the current object transformations glPushMatrix(); //set where to start the current object glTranslatef(0.0,-2,-6); glRotatef(angle,0,-2,-6); glutSolidSphere(0.5,50,50); glPopMatrix(); //end the current object transformations angle=+0.1; glutSwapBuffers(); } int main(int argc, char **argv) { // init GLUT and create window glutInit(&argc, argv); glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA); glutInitWindowPosition(100,100); glutInitWindowSize(500,500); glutCreateWindow("Hello World"); // register callbacks light(); glutDisplayFunc(renderScene); glutReshapeFunc(changeSize); glutIdleFunc(renderScene); // enter GLUT event processing loop glutMainLoop(); return 1; } Graphicstest::Graphicstest(void) { } In the renderscene where i draw,translate and rotate my 2 spheres. It does not seem to rotate the spheres continuously. What am i doing wrong?

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