tsJensen.com

Windows Azure Tools SDK (November 2009) Refactor or Restart?

Tyler Jensen — Sun, 15 Nov 2009 22:42:06 GMT

The 1.0 release of Windows Azure SDK is now available. Download and read about what’s new here. Sadly, the AspProviders sample project was not included. I spent a few hours trying to bandage it up, but it was a hopeless cause. If a new AspProviders sample is not soon forthcoming, it will be easier to write one from scratch using the new SDK and the new project templates.

When I tried to run my old project, after modifying some references to match those of a fresh project created with the new Visual Studio templates, the first thing that popped was a new local storage database script dialog result:

I’ve not explored them in detail but there are several new tables, some stored procedures and a few user defined functions in the new dev storage database.

I clicked okay and before I got my next error, I noticed the new baloon dialog name for the dev fabric, Windows Azure Simulation Environment:

I also compared the csCFG and and csDEF config files for the Azure cloud service project. The XML namespace is the same and as near as I can tell there are no changes there.

The next thing I noticed was a new class in the web role of the new project template. Seems we now have a “Windows Service”-like OnStart and RoleEnironmentChanging set of startup and status change event handlers. This will be highly useful for web role applications that may have resource cleanup needs.

public class WebRole : RoleEntryPoint
{
	public override bool OnStart()
	{
		DiagnosticMonitor.Start("DiagnosticsConnectionString");

		// For information on handling configuration changes
		// see the MSDN topic at http://go.microsoft.com/fwlink/?LinkId=166357.
		RoleEnvironment.Changing += RoleEnvironmentChanging;

		return base.OnStart();
	}

	private void RoleEnvironmentChanging(object sender, RoleEnvironmentChangingEventArgs e)
	{
		// If a configuration setting is changing
		if (e.Changes.Any(change => change is RoleEnvironmentConfigurationSettingChange))
		{
			// Set e.Cancel to true to restart this role instance
			e.Cancel = true;
		}
	}
}

Another bit of great news is that the StorageClient goes from “sample” project to part of the release libraries. There were ample changes there which appear to have broken the AspProviders sample project severely. While that explains the missing AspProviders project disappointment, I do hope that it means the changes in the StorageClient namespace will make using Azure storage easier.

Much more to learn and blog about with the new release, but it looks as though I’ll need to start over on my “Aventure” sample. I’m glad that I don’t have loads of code to refactor to the new release. It makes starting over less painful. For those who have written large projects relying on the beta, all I can say is, “beta = subject to change.”

OraHelper – An Oracle Version of the SqlHelper Class

Tyler Jensen — Wed, 21 Oct 2009 15:05:51 GMT

A very long time ago, I wrote a little helper class clone of SqlHelper for Oracle which I called OraHelper. I haven’t looked at or touched the code in years, but I regularly get email asking where it’s gone to. It appears that the www.asp.net community gallery still refers to it but their link is broken. Rather than attempt to get them to fix the link, I’m posting it here.

Download OraHelper (12KB) here.

I don’t know how well this code works anymore. I’ve no Oracle database against which I can test it. I recall that one inquirer indicated that he wanted the code because he was limited to the .NET Framework 1.1. I found that rather sad to think about given how comfortable I’ve become with generics and lambdas of late.

For those of you who are doing .NET database access to Oracle, you may be helped even more by looking at Oracle’s .NET Developer Center. I can’t speak for the state of their current support. Perhaps there are readers that could post more informed comments on the subject here.

Building Enterprise Applications with Silverlight 3, .NET RIA Services and Windows Azure Part 1

Tyler Jensen — Mon, 19 Oct 2009 01:58:29 GMT

After spending last weekend working on and blogging about Silverlight 3 and .NET RIA services, I decided I’d look to build out a membership, profile and role provider that would use Windows Azure storage. Much to my delight, I stumbled into the AspProvidersDemo code that comes with the Windows Azure SDK or perhaps the Visual Studio 2008 Tools for Azure.

No matter, you need them both to follow along with this post. If you have not already, you should look at my previous post and make sure you prepare your environment for Silverlight 3 in addition to signing up for your Azure account and installed the tools mentioned

You can download the entire solution file (434KB) and skip to the momentous striking of your F5 key if you like. Or you can follow along here and blunder through this adventure as I did. (I recommend cheating now and downloading the code.)

Here’s the step-by-step details. I’ll try to spare the you excruciating minutiae and keep it as exciting as possible.

I started by creating a standard Cloud Service application called MyFilesCloudService with a web role called WebFilesRole. I then added a Silverlight Business Application called Adventure. Unfortunately, this template does not allow you to select the web role application to host the Silverlight app.

I removed the Adventure.Web application and in the web role’s project properties added the Silverlight app in the Silverlight Application tab. (ERROR: This turned out to be a problem which I solved by added a throwaway standard Silverlight app to the solution, selecting the WebFilesRole app as the host. I am still not certain why, but I’ll spare you the grisly details of experimentation with the web.config. If you haven’t already, this is a good place to stop and download the code.)

I copied the AspProviders and StorageClient projects from the Azure SDK demos folder into the solution directory and added them to the solution. I also copied the relevant sections from the web.config for the web role and the ServiceConfiguration.cscfg and ServiceDefinition.csdef files in cloud service project.

I hit F5 for kicks and get (via Event Viewer) an event 3007, “A compilation error has occurred.” Upon further digging I realize that the profile provider is configured to inherit it’s ProfileBase from UserProfile. The class is in the demo’s web role. Steal that too. Here it is as added to the web role in my project:


using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Profile;
using System.Web.Security;

namespace WebFilesRole
{
   public class UserProfile : ProfileBase
   {
      public static UserProfile GetUserProfile(string username)
      {
         return Create(username) as UserProfile;
      }

      public static UserProfile GetUserProfile()
      {
         return Create(Membership.GetUser().UserName) as UserProfile;
      }


      [SettingsAllowAnonymous(false)]
      public string Country
      {
         get { return base["Country"] as string; }
         set { base["Country"] = value; }
      }

      [SettingsAllowAnonymous(false)]
      public string Gender
      {
         get { return base["Gender"] as string; }
         set { base["Gender"] = value; }
      }

      [SettingsAllowAnonymous(false)]
      public int Age
      {
         get { return (int)(base["Age"]); }
         set { base["Age"] = value; }
      }
   }
}

I boldly hit F5 again and get this gem:

Configuration Error
Initialization of data service structures (tables and/or blobs) failed!
The most probable reason for this is that the storage endpoints are not configured correctly.
Line 133: type="Microsoft.Samples.ServiceHosting.AspProviders.TableStorageSessionStateProvider"

A little searching and googling and I learn that I need to right-click on my cloud service application and select “Create Test Storage Tables.” I do it and bada-bing, I get this nice dialog and Output window text:

DevTableGen : Generating database 'MyFilesCloudService'
DevTableGen : Generating table 'Roles' for type 'Microsoft.Samples.ServiceHosting.AspProviders.RoleRow'
DevTableGen : Generating table 'Sessions' for type 'Microsoft.Samples.ServiceHosting.AspProviders.SessionRow'
DevTableGen : Generating table 'Membership' for type 'Microsoft.Samples.ServiceHosting.AspProviders.MembershipRow'
===== Create test storage tables succeeded =====

Aha! I go examine my local SQL Server instance and sure enough, there’s a new DB called MyFilesCloudService with some interesting tables. You can take at look at your own when you’ve read far enough along here to learn to click that “Create Test Storage Tables” magic context menu item too.

So I experiment a little and create a couple of test tables like this:


using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using Microsoft.Samples.ServiceHosting.StorageClient;

namespace WebFilesRole
{
   public class MyTestDataServiceContext : TableStorageDataServiceContext
   {
      public IQueryable
Roles { get { return this.CreateQuery
("MyTest"); } } } public class MyTestRow : TableStorageEntity { public string MyTestName
{ get; set; } } }

Note the nice and easy TableStorageEntity and it’s TableStorageDataServiceContext. Just don’t make the mistake I did and forget to name the property something unique. I tried Roles (yeah, a copy/past error) and got a nasty message like this:

No table generated for property 'Roles' of class 'WebFilesRole.MyTestDataServiceContext' because the name matches (or differs only in case) from the name of a previously generated table

I add an AppInitializer class to make sure these tables get created in the cloud when run there. First, I add a bit of code to the Application_BeginRequest method in the Global.asax.cs (the one I just added but didn’t tell you about).


protected void Application_BeginRequest(object sender, EventArgs e)	
{	
   HttpApplication app = sender as HttpApplication;   
   if (app != null)   
   {   
      HttpContext context = app.Context;   
      AppInitializer.Initialize(context);   
   }   
}

I then add the initializer class at the bottom of that same code file.


internal static class AppInitializer
{
   static object lob = new object();
   static bool alreadyInitialized = false;
   public static void Initialize(HttpContext context)
   {
      if (alreadyInitialized) return;
      lock (lob)
      {
         if (alreadyInitialized) return;
         InitializeAppStartFirstRequest(context);
         alreadyInitialized = true;
      }
   }

   private static void InitializeAppStartFirstRequest(HttpContext context)
   {
      StorageAccountInfo account = StorageAccountInfo.GetDefaultTableStorageAccountFromConfiguration();
      TableStorage.CreateTablesFromModel(typeof(Microsoft.Samples.ServiceHosting.AspProviders.MembershipRow));
      TableStorage.CreateTablesFromModel(typeof(Microsoft.Samples.ServiceHosting.AspProviders.RoleRow));
      TableStorage.CreateTablesFromModel(typeof(Microsoft.Samples.ServiceHosting.AspProviders.SessionRow));
      TableStorage.CreateTablesFromModel(typeof(Room));
   }
}

I then add some test code into the Default.aspx.cs which I won’t bore you with here. You can look at it in the downloaded solution. I got a weird error with the session test, but after a reboot, it went away, so I’ll chalk that up to the development fabric being a CTP.

Now I want to get back to working Silverlight into the picture. I need to create an admin user for my test login, so I add some code to the AppInitializer class in the Global.asax.cs file like this:


MembershipUser user = Membership.GetUser("admin");
if (null == user)
{
   //create admin user
   MembershipCreateStatus status = MembershipCreateStatus.Success;
   Membership.CreateUser("admin", "admin", "admin@admin.com", "admin-admin", "admin", 
      true, Guid.NewGuid(), out status);

   //add admin user to admin role
   if (status == MembershipCreateStatus.Success)
   {
      if (!Roles.RoleExists("admin"))
      {
         Roles.CreateRole("admin");
      }
      Roles.AddUserToRole("admin", "admin");
   }

   //add profile data to admin user
   UserProfile profile = UserProfile.Create("admin") as UserProfile;
   profile.Age = 40;    //not my true age
   profile.Country = "US";
   profile.Gender = "M";
   profile.Save();
}

I look at the UserProfile class and know that the DomainService’s User class needs the same properties in order for the Silverlight RiaContext to know about them. I discovered in the metadata code the following comments in the UpdateUser method of the System.Web.Ria.ApplicationServices.AuthenticationBase<T> base class used for the AuthenticationService domain service class:


// Remarks:
//     By default, the user is persisted to the System.Web.Profile.ProfileBase.
//     In writing the user to the profile, the provider copies each property in
//     T into the corresponding value in the profile. This behavior can be tailored
//     by marking specified properties with the System.Web.Ria.ApplicationServices.ProfileUsageAttribute.

I know now that I want the UserProfile and the User classes to have the same profile properties, so I add an interface above the UserProfile class like this:


public interface IUserProfile	
{	
   string Country { get; set; }   
   string Gender { get; set; }   
   int Age { get; set; }   
}

And then add the same properties found in UserProfile to the User class in the AuthenticationService.cs file as follows:


public class User : UserBase, IUserProfile   
{   
   // NOTE: Profile properties can be added for use in Silverlight application.   
   // To enable profiles, edit the appropriate section of web.config file.   
   
   // public string MyProfileProperty { get; set; }   
   
   public string Country { get; set; }   
   
   public string Gender { get; set; }   
   
   public int Age { get; set; }   
}

I try to run it and get the following error on the Silverlight app when I try to login using admin/admin: "The specified resource was not found." A little digging reveals that I need two things: first, some additions to the web.config file that I was missing, and second, the ServiceDefinition.csdef had to have it’s enableNativeCodeExecution set to true. Here’s the pieces:


<!-- handlers and httpHandlers sections require the following additions -->
<handlers>
   <add name="DataService" verb="GET,POST" path="DataService.axd" type="System.Web.Ria.DataServiceFactory, System.Web.Ria, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>		
</handlers>

<httpHandlers>
   <add path="DataService.axd" verb="GET,POST" type="System.Web.Ria.DataServiceFactory, System.Web.Ria, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false"/>		
</httpHandlers>

<!-- the ServiceDefinition.csdef gets the enableNativeCodeExecution set to true -->
<WebRole name="WebFilesRole" enableNativeCodeExecution="true">

Once those changes were made, I was able to run the Silverlight application, login using admin/admin and logout. Now one more item on the agenda for this post. I want to see the profile information we added in the AppInitializer code. So I modify the LoginControl.xaml and LoginControl.xaml.cs as follows.


<StackPanel x:Name="logoutControls" Style="{StaticResource LoginPanelStyle}">
   <TextBlock Text="welcome " Style="{StaticResource WelcomeTextStyle}"/>
   <TextBlock Text="{Binding Path=User.Name}" Style="{StaticResource WelcomeTextStyle}"/>
      <TextBlock Text="  |  " Style="{StaticResource SpacerStyle}"/>
      <TextBlock Text="" x:Name="ProfileText" Style="{StaticResource WelcomeTextStyle}"/>
      <TextBlock Text="  |  " Style="{StaticResource SpacerStyle}"/>
   <Button x:Name="logoutButton" Content="logout" Click="LogoutButton_Click" Style="{StaticResource LoginRegisterLinkStyle}" />
</StackPanel>

With the code behind changed like this:


private void UpdateLoginState()	
{	
   if (RiaContext.Current.User.AuthenticationType == "Windows")   
   {   
      VisualStateManager.GoToState(this, "windowsAuth", true);   
   }   
   else //User.AuthenticationType == "Forms"   
   {   
      VisualStateManager.GoToState(this,    
         RiaContext.Current.User.IsAuthenticated ? "loggedIn" : "loggedOut", true);   
   
      if (RiaContext.Current.User.IsAuthenticated)   
      {   
         this.ProfileText.Text = string.Format("age:{0}, country:{1}, gender:{2}",    
            RiaContext.Current.User.Age,    
            RiaContext.Current.User.Country,    
            RiaContext.Current.User.Gender);   
      }   
   }
}

Now when I login, I get to look at something like this:

Cool. In Part 2, I’ll modify the UserProfile to capture the data I want to keep in my Adventure application and complete the user registration changes to the Silverlight application as well as clean up and prepare the app for some real application development in follow-on posts.

If you have any questions or ways to do this better, I’d love to hear from you.

Silverlight 3 and .NET RIA Services Forms Security

Tyler Jensen — Mon, 12 Oct 2009 21:01:52 GMT

I finally carved out some time to experiment with Silverlight 3 and .NET RIA Services over the weekend. Specifically I wanted to experiment with Forms security and how one might secure a Silverlight "page" as well as the services on the server side along with a custom membership, role and profile providers. Here's the result.

Tools
Before you follow along on your own machine, be sure that you have these:

1. Visual Studio 2008 Pro (Visual Studio 2008 Professional Edition (90-day Trial))

2. Visual Studio 2008 SP1 (Microsoft Visual Studio 2008 Service Pack 1 (Installer))

3. Silverlight SDK (Microsoft® Silverlight™ 3 Tools for Visual Studio 2008 SP1)

4. RIA Services July 2009 Preview (Microsoft .NET RIA Services July 2009 Preview)

5. Download code for this post (download DemoAgRia.zip 427KB).

Once you have the tools installed, you can start a new Visual Studio project from the Silverlight projects types called Silverlight Business Application. Name yours whatever you like. I've chosen DemoAgRia.

The project template creates a Silverlight and ASP.NET Web Application project and populates them with a number of helpful artifacts to get us started. There are two DomainService classes, one for authentication and one for user registration. These services use the standard ASP.NET Membership, Role and Profile provider model.

You also get several "views" or Page and ChildWindow XAML controls with code-behind. These files are a familiar construct to any classic ASP.NET developer. Of course XAML is a whole new ballgame compared to the hodge podge of HTML. But rather than focus on these page and child window objects, I will focus this post on the security aspects of the app.

While the project template sets authentication to "Forms" based authentication there are no membership, role, or profile providers configured in the web.config. Since I'm going to create some custom providers in order to just experiment with the mechanics of security within the Silverlight and the web app, I'll just spin up some stub providers. Here's the web.config sections (including the "Forms" authentication node) for them:

<authentication mode="Forms"/>

<roleManager enabled="true" defaultProvider="AgRoleProvider">
  <providers>
    <clear />
    <add name="AgRoleProvider" type="DemoAgRia.Web.AgRoleProvider" />
  </providers>
</roleManager>
<membership defaultProvider="AgMembershipProvider">
  <providers>
    <clear />
    <add name="AgMembershipProvider" type="DemoAgRia.Web.AgMembershipProvider" />
  </providers>
</membership>
<profile enabled="true" defaultProvider="AgProfileProvider">
  <providers>
    <clear />
    <add name="AgProfileProvider" type="DemoAgRia.Web.AgProfileProvider" />
  </providers>
  <properties>
    <clear />
    <add name="PhoneNumber" />
    <add name="FullName" />
  </properties>
</profile>

Now I stub out the provider classes in the Providers folder of the web application. I won't post the code here because the implementation provides dumb data or place holders. Of course, a real set of providers, whether you use the AspSqlMembership provider or role your own, will do real authentication and provide real role and profile access. The stub membership class will authenticate any username and password to allow us to just play with the happy path for now.

Note the custom properties I've added to the profile provider above. These require some custom code in two places. First, in the profile provider class and then in the User class found in the AuthenticationService.cs file. Here's the code for both:

in AgProfileProvider.cs:

public override SettingsPropertyValueCollection GetPropertyValues(SettingsContext context, 
  SettingsPropertyCollection collection)
{
  string userName = context["UserName"].ToString(); //use this to look up real values for user

  SettingsPropertyValueCollection s = new SettingsPropertyValueCollection();
  foreach (SettingsProperty p in collection)
  {
    if (p.Name == "PhoneNumber") s.Add(new SettingsPropertyValue(p) { PropertyValue = "508.555.1212" });
    if (p.Name == "FullName") s.Add(new SettingsPropertyValue(p) { PropertyValue = "Tyler Jensen" });
    //NOTE: replace with real lookups
  }
  return s;
}

in AuthenticationService.cs:>

public class User : UserBase
{
  // NOTE: Profile properties can be added for use in Silverlight application.
  // To enable profiles, edit the appropriate section of web.config file.

  // public string MyProfileProperty { get; set; }
  public string FullName { get; set; }
  public string PhoneNumber { get; set; }
}

Now to use these new profile provider properties, let's modify some XAML in the LoginControl.xaml file so that rather than seeing the username of the logged in user, we'll see the FullName and the PhoneNumber.

Here's the existing XAML which we will modify:

<StackPanel x:Name="logoutControls" Style="{StaticResource LoginPanelStyle}">
  <TextBlock Text="welcome " Style="{StaticResource WelcomeTextStyle}"/>
  <TextBlock Text="{Binding Path=User.Name}" Style="{StaticResource WelcomeTextStyle}"/>
  <TextBlock Text="  |  " Style="{StaticResource SpacerStyle}"/>
  <Button x:Name="logoutButton" Content="logout" Click="LogoutButton_Click" Style="{StaticResource LoginRegisterLinkStyle}" />  
</StackPanel>

We now modify this XAML snippet to this:

 
<StackPanel x:Name="logoutControls" Style="{StaticResource LoginPanelStyle}">
  <TextBlock Text="welcome " Style="{StaticResource WelcomeTextStyle}"/>
  <TextBlock Text="{Binding Path=User.FullName}" Style="{StaticResource WelcomeTextStyle}"/>
  <TextBlock Text="  |  phone: " Style="{StaticResource SpacerStyle}"/>
  <TextBlock Text="{Binding Path=User.PhoneNumber}" Style="{StaticResource WelcomeTextStyle}"/>
  <TextBlock Text="  |  " Style="{StaticResource SpacerStyle}"/>
  <Button x:Name="logoutButton" Content="logout" Click="LogoutButton_Click" Style="{StaticResource LoginRegisterLinkStyle}" />
</StackPanel>

Now lets add a DomainService for fecthing some data. Right click on the web application's Services folder and select Add | New Item.

Of course, we don't have a data or object context class, so we don't have any to choose from in the dialog.

Leave "Enable client access" checked. We want a proxy class to automatically be generated from our service class on the server side. Just click OK and let's create our own custom DomainService.

Now you'll see something like this:

 
namespace DemoAgRia.Web.Services
{
  using System;
  using System.Collections.Generic;
  using System.ComponentModel;
  using System.ComponentModel.DataAnnotations;
  using System.Linq;
  using System.Web.Ria;
  using System.Web.Ria.Data;
  using System.Web.DomainServices;


  // TODO: Create methods containing your application logic.
  [EnableClientAccess()]
  public class DemoDataService : DomainService
  {
  }
}

I'll put it into the root of the namespace by lopping off the ".Services" in the namespace declaration. This is just a convenience to me. You can do with it what you like.

Now let's add a couple of simplistic methods. Be sure to decorate them with the ServiceOperation attribute or the build process will not autogenerate the DemoDataContext class and proxy class in the Silverlight client app.

 
[EnableClientAccess()]
public class DemoDataService : DomainService
{
  [ServiceOperation]
  public string GetApplicationName()
  {
    return "Demo Ag Ria";
  }

  [ServiceOperation]
  public string GetApplicationAddress()
  {
    return "http://www.demoagria.com";
  }
}

To use the DemoDataService on the client, let's try the following code in the Home.xaml.cs file. Note the two additional using statements and take special note that all calls to the server are asynchronous:

 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Windows.Data;
using System.IO;
using DemoAgRia.Web;
using System.Windows.Ria.Data;

namespace DemoAgRia
{
  public partial class Home : Page
  {
    public Home()
    {
      InitializeComponent();
    }

    // Executes when the user navigates to this page.
    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
      DemoDataContext ddc = new DemoDataContext();
      InvokeOperation<string> invAddress = ddc.GetApplicationAddress();
      invAddress.Completed += new EventHandler(invAddress_Completed);
      
      InvokeOperation<string> invAppName = ddc.GetApplicationName();
      invAppName.Completed += new EventHandler(invAppName_Completed);
    }

    void invAppName_Completed(object sender, EventArgs e)
    {
      InvokeOperation<string> op = sender as InvokeOperation<string>;
      string appName = op.Value;
      this.ContentText.Text += string.Format("{0}app name: {1}", Environment.NewLine, appName);
    }

    void invAddress_Completed(object sender, EventArgs e)
    {
      InvokeOperation<string> op = sender as InvokeOperation<string>;
      string address = op.Value;
      this.ContentText.Text += string.Format("{0}address: {1}", Environment.NewLine, address);
    }

  }
}

If you F5 and run a debug test, you'll note that the text in the Home page gets modified as expected.

Now let's add a RequiresAuthentication to the GetApplicationName method:

[ServiceOperation, RequiresAuthentication]
public string GetApplicationName()
{
  return "Demo Ag Ria";
}

Run the app again and you will notice that the GetApplicationName's InvokeOperation<string> object's Value property is null. Now login and click the About page link and then go back to the Home page link. Note that the text has maintained it's state. We're not clearing it, but this time we've added text which includes the app name.

Now try modifying the GetApplicationAddress method like this:

[ServiceOperation, RequiresRoles("Supervisor")]
public string GetApplicationAddress()
{
  return "http://www.demoagria.com";
}

Since the stubbed role provider gives your logged in user the Admin and Analyst role, you can run this and see that you are getting a null value for the operation. Now change the role to "Admin" and try the same thing. This time when you login and come back to the Home page you'll see what we'd expect.

Getting this far was almost enough fun, but then I wondered how I would prevent a user from navigating to a specific Silverlight page if they were not authenticated. There are probably better ways, but here's the solution I arrived at after a little fiddling.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Windows.Navigation;

namespace DemoAgRia
{
  public class PageSecurity
  {
    private Page page;
    private string url;

    public PageSecurity(Page page)
    {
      this.page = page;
    }

    public void Authenticate()
    {
      Authenticate(null);
    }

    public void Authenticate(string url)
    {
      this.url = url;
      if (!RiaContext.Current.User.IsAuthenticated)
      {
        ErrorWindow ew = new ErrorWindow("You must be logged in to view this page.", 
          "Using this page is not allowed unless you are logged in.");
        ew.Title = "Authentication Required";
        ew.IntroductoryText.Text = "Not Authenticated";
        ew.LabelText.Text = "Message";
        ew.Closed += new EventHandler(ew_Closed);
        ew.Show();
      }
    }

    void ew_Closed(object sender, EventArgs e)
    {
      if (null == url)
        this.page.NavigationService.GoBack();
      else
      {
        if (!url.StartsWith("/")) url = "/" + url;
        try
        {
          this.page.NavigationService.Navigate(new Uri(url, UriKind.Relative));
        }
        catch
        {
          this.page.NavigationService.GoBack(); 
        }
      }
    }
  }
}

To test this code, I've added the following code to the About.xaml.cs code to see how it plays.

protected override void OnNavigatedTo(NavigationEventArgs e)
{
  PageSecurity ps = new PageSecurity(this);
  ps.Authenticate("Home");
}

Now all you have to do is download the code and you've got a headstart on Silverlight and .NET RIA Services security. Let me know if you find any exciting improvements or alternatives.

Reliability Equals Simplicity

Tyler Jensen — Thu, 10 Sep 2009 02:53:36 GMT

I am extremely impressed by the sage wisdom of Sir Charles Antony Richard Hoare's The Emperor's Old Clothes given at his acceptance of the Turing Award in 1980 and subsequently published by the Association for Computing Machinery (ACM) in 1981. Here are my favorite excerpts. I hope you will read the entire text using the link below.

"You know, you shouldn't trust us intelligent programmers. We can think up such good arguments for convincing ourselves and each other of the utterly absurd."
...
"Programmers are always surrounded by complexity; we cannot avoid it. Our applications are complex because we are ambitious to use our computers in ever more sophisticated ways. Programming is complex because of the large number of conflicting objectives for each of our programming projects. If our basic tool, the language in which we design and code our programs, is also complicated, the language itself becomes part of the problem rather than part of its solution."
...
"At first I hoped that such a technically unsound project would collapse but I soon realized it was doomed to success. Almost anything in software can be implemented, sold, and even used given enough determination. There is nothing a mere scientist can say that will stand against the flood of a hundred million dollars. But there is one quality that cannot be purchased in this way--and that is reliability. The price of reliability is the pursuit of the utmost simplicity. It is a price which the very rich find most hard to pay."
...
"The mistakes which have made in the last twenty years are being repeated today on an even grander scale."
...
"If only we could learn the right lessons from the successes of the past, we would not need to learn from our failures."
...
"To have our best advice ignored is the common fate of all who take on the role of consultant, ever since Cassandra pointed out the dangers of bringing a wooden horse within the walls of Troy."

The Emperor's Old Clothes
Sir Charles Antony Richard Hoare
Creator of the Quicksort algorithm
1980 Turing Award Winner
© 1981 ACM 0001-0782/81/0200-0075

Full text here in PDF.

Having accidentally browsed into this today, I reiterate the axiom that complexity is the enemy of sound software development and hereby recommit to following the path of simplification, learning more lessons from my successes to avoid more failures and to sometimes keeping my best advice to myself.

Enum to Dictionary with Description Attribute Reflection

Tyler Jensen — Fri, 28 Aug 2009 03:15:44 GMT

A week ago in a misguided attempt to make things easier, I created something like the following code. My mistake was not in creating the code necessarily, but in applying it to data driven auto generated enums. If you have those, don’t use this.

If you have nice, well behaved static enums wandering around your code and you wish you had a nice way to convert that enum to a usable Dictionary<int, string>, then you’ve come to the right place. So dress up that drab enum with a Description attribute like you see below and call EnumConverter.ConvertToDictionary<DrabEnum>();

And let me know how it works out.


using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Data.Linq;
using System.Text;
using System.Reflection;
using System.Collections;

namespace FunStuff
{
  public enum FunEnum
  {
    [Description("Happy Enum")]
    Happy = 1,

    [Description("Sad Enum")]
    Sad = 2
  }


  public static class EnumConverter
  {
    private static object lo = new object(); //used for locking access to the Cache
    private static Dictionary<Type, Dictionary<int, string>> enumStore = 
      new Dictionary<Type, Dictionary<int, string>>();

    /// <summary>
    /// Returns thread safe copy of enum value and name dictionary. Where Description <br />
    /// attribute exists, returns the description value.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <returns></returns>
    public static Dictionary<int, string> ConvertToDictionary<T>() where T : IComparable
    {
      lock (lo)
      {
        Type t = typeof(T);
        if (!t.IsEnum) throw new ArgumentException("T must be an enum.");
        if (!enumStore.ContainsKey(t)) enumStore.Add(t, Load(t));
        return new Dictionary<int, string>(enumStore[t]);
      }
    }

    private static Dictionary<int, string> Load(Type t)
    {
      Dictionary<int, string> list = new Dictionary<int, string>();
      foreach (MemberInfo m in t.GetMembers())
      {
        if (m.MemberType == MemberTypes.Field && m.Name != "value__")
        {
          string label = m.Name;
          foreach (var att in m.GetCustomAttributes(false))
          {
            DescriptionAttribute da = att as DescriptionAttribute;
            if (null != da)
            {
              if (da.Description.Length > 0)
              {
                label = da.Description;
              }
            }
          }
          int id = Convert.ToInt32(System.Enum.Parse(t, m.Name));
          list.Add(id, label);
        }
      }
      return list;
    }
  }
}

Windows 7 Repave Checklist

Tyler Jensen — Mon, 27 Jul 2009 22:30:03 GMT

In anticipation of repaving my Vista x64 machine with Windows 7 after the MSDN release on August 6, I’ve prepared my wish list of hardware upgrades I’d like to do at the same time I pave the machine with the new OS.

Should the family financial officer (FFO) decline to approve my purchase request, I’ll at least sneak in the SSD purchase.

Update (new list, bigger appetite):

Qty	Description	Price
2	SUPER TALENT 12GB (3 x 4GB) 240-Pin DDR3 SDRAM DDR3 1333	$ 739.98
1	ASUS Z8NA-D6C Dual LGA 1366 Intel 5500 ATX Dual Intel Xeon 5500 Series	259.99
2	Intel Xeon E5520 Nehalem 2.26GHz LGA 1366 80W Quad-Core	765.98
1	SUPER TALENT MasterDrive SX SAM56GM25S 2.5" 256GB SATA II MLC Internal SSD	629.99
Total		$ 2,395.94

What plans do you have for your Windows 7 upgrade?

Drool….

Getting Started with Windows Azure

Tyler Jensen — Tue, 21 Jul 2009 22:26:23 GMT

Here’s the content of the most exciting email I’ve received lately (invite code redacted of course):

Thank you for your interest in Windows® Azure™.

Your invitation code is xxxxx-xxxxx-xxxxx-xxxxx-xxxxx.

You can now sign up for a Windows Azure account at http://lx.azure.microsoft.com/fs . Please keep this email in a safe place.

This invitation to participate in the Windows Azure Community Technical Preview is subject to the following usage limits:

        Total compute usage: 2000 VM hours
        Cloud storage capacity: 50GB
        Total storage bandwidth: 20GB/day

During the CTP, we reserve the right to suspend your account activity (this does not imply we will delete your cloud storage) if you exceed these usage limits.

Sincerely,
Windows Azure Platform Team

You have received this email because you registered as being interested in the Community Technology Preview (CTP) of Windows Azure. As a participant in the Windows Azure CTP program, you will continue to receive emails related to that program unless you end your participation by emailing azinvite@microsoft.com with “END PARTICIPATION” in the subject line.

To ensure proper delivery of future updates please add azinvite@microsoft.com to your address book or safe-senders list.

Microsoft respects your privacy. To learn more about Microsoft's privacy policy, please click here.

Microsoft Corporation
One Microsoft Way
Redmond, WA 98052

I’m very excited to begin learning to develop against Azure in all my spare time. If I learn anything worthy of note here, I’ll share it. Just too many things to dabble in and too little time.

Will the Enterprise Adopt Silverlight 3 for LOB?

Tyler Jensen — Sun, 12 Jul 2009 20:59:43 GMT

With the release of Silverlight 3 on Friday, I’m wondering whether the enterprise (that mythical stereotype) will adopt Silverlight 3 for line of business (LOB) applications. The official “what’s new” section included the following items that I found very interesting:

Improving Rich Internet Application Productivity. New features include:

60+ controls with source code : Silverlight 3 is packed with over 60 high-quality, fully skinnable and customizable out-of-the-box controls such as charting and media, new layout containers such as dock and viewbox, and controls such as autocomplete, treeview and datagrid. The controls come with nine professional designed themes and the source code can be modified/recompiled or utilized as-is. Other additions include multiple selection in listbox controls, file save dialog making it easier to write files, and support for multiple page applications with navigation.

Deep Linking. Silverlight 3 includes support for deep linking, which enables bookmarking a page within a RIA.

Search Engine Optimization (SEO). Silverlight 3 enables users to solve the SEO-related challenges posed by RIAs.By utilizing business objects on the server, together with ASP.NET controls and site maps, users can automatically mirror database-driven RIA content into HTML that is easily indexed by the leading search engines.

Enhanced Data Support Silverlight 3 delivers:
Element to Element binding : UI designers use binding between two UI properties to create compelling UI experiences. Silverlight now enables property binding to CLR objects and other UI components via XAML, for instance binding a slider value to the volume control of a media player.
Data Forms. The Data Form control provides support for layout of fields, validation, updating and paging through data.
New features for data validation which automatically catch incorrect input and warn the user with built-in validation controls.
Support for business objects on both client and server with n-Tier data support. Easily load, sort, filter and page data with added support for working with data. Includes a new built-in CollectionView to perform a set of complex operations against server side data. A new set of .NET RIA services supports these features on the server.

Improved performance, through:
Application library caching,which reduces the size of applications by caching framework on the client in order to improve rendering performance.
Enhanced Deep Zoom, allows users to fluidly navigate through larger image collections by zooming.
Binary XML allows communication with the server to be compressed, greatly increasing the speed at which data can be exchanged.
Local Connection This feature allows communication between two Silverlight applications on the client-side without incurring a server roundtrip: for instance a chart in one control can communicate with a datagrid in another.

I’ve just downloaded the bits and will begin exploring the new controls and just how easy it is or is not to build applications. My only criteria at the moment is whether or not the applications are as easy to build as a Windows Forms application. Obviously there are far more important evaluation criteria, but I’m wondering whether my stated criteria here will be the more common question raised in the enterprise. That is, can we build apps faster, easier, better with this? If not, I’m not sure the enterprise will get too awfully excited about it unless a clear case can be made for replacing the often time consuming, error prone web application development process with a simpler Silverlight 3 development process.

One way or another, I’m excited about Silverlight 3 and eager to dive in and have some fun.

Favorite Win 7 RC Feature

Tyler Jensen — Sat, 02 May 2009 21:20:01 GMT

Here’s my favorite feature’s of Windows 7 release candidate right after install into a VMware virtual machine.