Guy Burstein's Blog

Windows 7: Register a New File Associations

Guy Burstein — Wed, 01 Jul 2009 11:29:40 GMT

Windows 7: Register a New File Associations

Lets say I have a standard Windows Forms application that works with .guy file types (which is nothing but a text file):

This application can be launched from the command line with a file name as an argument:

> TextFilesViewer.exe SampleFile.guy

In this case, the application displays the file contents in the multiline textbox above:

private void ViewerForm_Load(object sender, EventArgs e)
{
  string[] args = Environment.GetCommandLineArgs();
  if (args.Length > 1)
  {
    string[] lines = File.ReadAllLines(args[1]);
    this.txtFileContents.Lines = lines;
  }
}

Since this application is the only application that knows how to work with .guy files, we would like to associate this file type with my application.

In order to do that, add a reference to the RegistrationHelper sample. This is an exe that performs the actual registration of the file association and needs to be run with admin privileges. It can be found as a sample project in the WindowsAPICodePack\Samples\Shell\TaskbarDemo\CS\RegistrationHelper folderer

After you have added the reference you should add another file from the samples folder - RegistrationHelper.cs which is found in the WindowsAPICodePack\Samples\Shell\TaskbarDemo\CS\TaskbarDemo\ folder.
This file exposes several static methods that invoke the helper as another process with admin privileges.

private void registerFileTypeToolStripMenuItem_Click(object sender, EventArgs e)
{
  string appId = "TextFilesViewer";
 
  RegistrationHelper.RegisterFileAssociations(
    appId,
    false,
    appId,
    string.Format("{0} %1", Assembly.GetExecutingAssembly().Location),
    ".guy");
}

Notice that one of the parameters of RegistrationHelper.RegisterFileAssociations() method is the Application ID which is set to a meaningful name. I’ll talk more on the Application ID in later posts to understand its impact on additional features.

When the user tries to associate the file type, RegistratioinHelper will require admin privileges. If User Account Control (UAC) is enabled on your machine, you will be prompted to allow the registration utility to modify the registry.

After the registration completes, you can double click and .guy files in your machine, and the TextFilesViwer application will be launched to display its content.

Enjoy!

Getting Started with Windows 7 Development Through Windows API Code Pack

Guy Burstein — Wed, 01 Jul 2009 11:28:36 GMT

Getting Started with Windows 7 Development Through Windows API Code Pack

Windows 7 is said to be a great operating system, much more secure, faster and productive than its predecessors. As with every version of Windows, it also contains a huge amount of new features exposed for developers as API’s, unfortunately, as unmanaged code. The Windows SDK team is working on a project called Windows API Code Pack which provides managed wrappers for Windows API’s.

Downloading the Windows API Code Pack, you’ll get a Zip file containing both the Windows API Code Pack Source and Samples. In the next few posts I’ll explore the new features of the new OS and provide the managed ways to leverage them from your applications using the above source and samples.

Enjoy!

How to build a Simple IE8 Accelerator

Guy Burstein — Mon, 29 Jun 2009 11:08:09 GMT

How to build a Simple IE8 Accelerator

This post is a step by step guide for building IE8 Accelerators.

A Short Introduction to IE8 Accelerators

Accelerators are used to make the user more productive while surfing the net, by:

1. Speeding up the process of getting additional information about a meaningful string (address, stock quote, a product, a twitter account name, etc). In this sample

2. Allowing user to perform a quick action on a selected text.

From a technical perspective, Accelerators define 2 actions: Preview and Execute. When the user selects some text and hover over an accelerator, the Preview action is being performed - the selected text is sent to a defined url, that returns a 320x240 web page with a preview of the data.
When the user clicks the Accelerator, the Execute action is performed and the browser navigates to a page passing it the selected text as a parameter.

To build IE8 Accelerators, we have several steps to do:

Building an Accelerator Page
Defining the Accelerator OpenService Xml
Registering the Accelerator with IE8
Using the Accelerator

To make sure this guide is generic enough for every Accelerator you may think of and not just for Twitter profiles, I am leaving the twitter logic to the last part of this post.

1. Building an Accelerator Page

Create a new ASP.Net Web Application in Visual Studio 2008 or open an existing one.

Add a new Web Form for the Accelerator Preview. In the page code behind, extract the query string parameters write them to the Response object:

protected void Page_Load(object sender, EventArgs e)
{
  foreach (string param in Request.QueryString.AllKeys)
  {
    Response.Write(param + " = " + Request.QueryString[param] + "<br />");
  }
}

Test the page: Navigate to the accelerator’s url, and add several parameters. For example:

http://localhost:16319/ShowTwitterUser.aspx?data1=guy&data2=burstein

Defining the Accelerator OpenService Xml

In order to register the Accelerator with a user’s browser, we have to create an xml file with the details of the Accelerator.

Add an Xml file to the web application that defines the Accelerators metadata required by the browser.

<openServiceDescription        
      xmlns=http://www.microsoft.com/schemas/openservicedescription/1.0>
  <homepageUrl>http://www.bursteg.net/</homepageUrl>
  <display>
    <name>Twitter Profile Accelerator</name>
    <icon>http://www.twitter.com/favicon.ico</icon>
  </display>
  <activity category="Define">
    <activityAction context="selection">
      <preview action="http://www.bursteg.net/Twitter/ShowTwitterUser.aspx">
        <parameter name="selection" value="{selection}" />
      </preview>
      <execute action="http://www.bursteg.net/Twitter/ShowTwitterUser.aspx">
        <parameter name="documentUrl" value="{documentUrl}" />
        <parameter name="documentTitle" value="{documentTitle}" />
        <parameter name="documentDomain" value="{documentDomain}" />
        <parameter name="documentHost" value="{documentHost}" />
        <parameter name="selection" value="{selection}" />
      </execute>
    </activityAction>
  </activity>
</openServiceDescription>

Few things to notice in the Accelerator Xml:

1. There is some meta data about the accelerator such as homepage Url and the display name and icon.

2. The Activity node defines a category to which this accelerator belongs to. There are some default categories like Map, Translate, Blog etc, but users can manage their categories using the Manage Add-ons Dialog.

3. As described earlier, the accelerator defines 2 actions, preview and execute, each defines a Url to call to when clicked / previewed, and several parameters to pass to the target page.

Register the Accelerator with the User’s Browser

In a page of your chose (for example Default.aspx) add a button that registers the accelerator when clicked:

<input id="btnRegister" type="button" value="Add Accelerator to IE8"  
      onclick="BLOCKED SCRIPTwindow.external.AddService('TwitterProfileAccelerator.xml');" />

When the user clicks on the above button, a dialog pops us asking his permission to add this accelerator to his browser, and whether to make it the default accelerator in its category.

Using the Accelerator

After the user has added the accelerator to his browser he can start using it. Select some text and the accelerator box will appear next to it. Click on it add hover over the new accelerator. This should make an HTTP request to the accelerator page passing it the text you have selected.

If you click on the accelerator, IE8 will open the target page in a new tab passing it the selected text and additional information as defined in the accelerator xml.

Summary

In this pot I took the steps needed to build an accelerator. You can follow them you build your own accelerators and add additional logic to provide more interaction with your uses.

Enjoy!

חיפוש מוצרים באתר זאפ עם Internet Explorer 8

Guy Burstein — Thu, 11 Jun 2009 08:21:27 GMT

חיפוש מוצרים באתר זאפ עם Internet Explorer 8

אתמול קיבלתי מייל מחבר שלי:

“לא תאמין – היום חברה שלי ואני חוגגים שנה יחד, ואני מחפש לה מתנה. אני חייב לצאת גדול כי היא קנתה לי Xbox !!!”

אני לא יודע מה התגובה הראשונה שלכם כשאתה קוראים את מה שחבר שלי כתב לי, אבל הדבר הראשון שעלה לי לראש זה – בואו נראה כמה באמת החברה שלו השקיעה…
אז כדי לדעת כמה בימינו אלה עולה Xbox, סביר להניח שהייתי פותח טאב חדש, גולש לאתר השוואת המחירים – זאפ ומבצע חיפוש למחרוזת Xbox כדי לראות כמה הוא עולה.

עם Internet Explorer 8, זה הרבה יותר פשוט. כאשר מסמנים טקסט כלשהו באינטרנט, פתאום מופיע הלחצן הכחול הזה:

שכאשר לוחצים עליו, נפתחת רשימה של Accelerators (או בעברית – מאיצי גלישה) שמאפשרים לי להפעיל כל מיני שירותים על הטקסט שסימנתי. לדוגמא, אני יכול להפעיל את ה- Accelerator של חיפוש פריטים בזאפ ולקבל את התוצאה הבאה:

ה- Accelerator פונה לאתר זאפ, ומציג לי את הפריטים שעונים לשם Xbox עם התמונה שלהם, טווחי המחירים ומידע נוסף. ובשביל לקבל את כל זה הייתי צריך בסך הכל לסמן טקסט ולהפעיל Accelerator. הרבה יותר פשוט מקודם!

אם גם אתם רוצים להוסיף את ה- Accelerator של חיפוש פריטים בזאפ ל- Explorer שלכם, תוכלו לעשות את זה מתוך גלריית ההרחבות של Internet Explorer 8 שמכילה עוד הרבה הרחבות שפותחו ע”י אתרים מובילים בארץ. את כל ההרחבות של אתר זאפ תוכלו למצוא כאן.

בהמשך אספר על עוד הרחבות ל- Internet Explorer 8 שפותחו בארץ…

תהנו!

Getting Started with jQuery in Visual Studio 2008

Guy Burstein — Fri, 05 Jun 2009 16:06:22 GMT

Getting Started with jQuery in Visual Studio 2008

In this post I’ll talk about adding jQuery IntellSense in Visual Studio 2008, and how to add jQuery to a simple Web Application inside Visual Studio 2008.

jQuery IntelliSense in Visual Studio 2008 - KB946581

In order to use jQuery in Visual Studio 2008 with IntelliSence a hotfix for Visual Studio 2008 must be installed:

Download the hotfix from Connect
Run the executable and extract its contents to a folder in your hard drive.
Make sure all instances of Visual Studio 2008 are closed, and run VS90-KB946581.exe from the above folder.

Download the Latest jQuery Library + Documentation

To use jQuery in Visual Studio 2008, and enjoy its IntelliSense, you should download 2 javascript files. One contains the actual jQuery library, and the second contains the library with documentation for Visual Studio 2008 to display its IntelliSense.

Go to jQuery Official Download Page
Scroll down and find the Current Release section.
Download the Uncompressed version (jquery-1.2.6.js) and the documentation for Visual Studio (jquery-1.2.6-vsdoc.js).

Using jQuery in a Visual Studio 2008 Web Application

In a new Web Application or inside an existing one, add the jQuery scripts into a certain folder.

In a web page (or a master page), add a reference to the jQuery library:

<head runat="server">
  <title>jQuery Sample</title>
 
  <script src="scripts/jquery-1.2.6.js"         
          type="text/javascript" ></script>
 
</head>

Then, in any javascript function you can start using jQuery functions and enjoy the IntelliSense in Visual Studio 2008.

A Simple Example of Using jQuery Functions

For example, Assuming that you have a page with the following content in it:

<form id="form1" runat="server">
<div>
  <input type="text" class="inputs" id="txtName"       
         value="Enter Text Here" />
  <input type="button" class="inputs" id="btnSubmit"       
         value="Click Me" onclick="handleButtonClick();" />
</div>
</form>

This form contains a single textbox followed by a button.

The handleButtonClick() function handles the button onclick event.

<script type="text/javascript">
  function handleButtonClick() {
  }
</script>

The way jQuery works is by selecting DOM elements and then doing something with them, such as executing a function or applying some properties. For example:

<script type="text/javascript">
  function handleButtonClick() {
    $("#txtName").css("border", "solid 2px red");
  }
</script>

The above method uses the selector function $ to select DOM elements (in this case – a single element with id = txtName) and to apply a style property of a red border. Running this page and clicking the button results in this output:

Summary

In this post I talked about the steps you should follow in order to use jQuery in Visual Studio 2008 with InstelliSense support. Then, we used jQuery in a simple web application.

ASP.Net MVC on Windows Azure | ASP.Net MVC Web Role

Guy Burstein — Sat, 23 May 2009 13:44:38 GMT

ASP.Net MVC on Windows Azure | ASP.Net MVC Web Role

When you install Windows Azure Tools for Visual Studio, you only get a project template for an ASP.Net Web Role. In this post I’ll talk about how to create a new ASP.Net MVC Web Role or move an existing ASP.Net MVC Application to Windows Azure.

There are 2 ways to do this:

Manually adding an ASP.Net MVC application as a Web Role (suitable both for a new ASP.Net MVC application and for an existing one).
Use a Project Template to simply create a new ASP.Net MVC Web Role (new ASP.Net MVC application only).

Creating a New ASP.Net MVC Web Role

The following steps apply both for creating a new ASP.Net MVC application and to moving an existing ASP.Net MVC application to Windows Azure.

1. Create an empty ASP.Net MVC Application (with or without a test project), or make sure you have an existing ASP.Net MVC application that you want to move to the Windows Azure.

2. Close this solution and create a new Blank Cloud Service. Make sure you start Visual Studio as an administrator because working with the Development Fabric requires that.

3. Add an existing project to the cloud service and select the ASP.Net MVC Application you have created earlier.

4. Right click the ASP.Net MVC project and select Unload Project.

5. When the project is unloaded, right click it and edit the project file.

6. The project file opens in the XML Editor.

<Project ToolsVersion="3.5" DefaultTargets="Build" ...>
  <PropertyGroup>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    ...
  </PropertyGroup>
  ...        
</Project>

Inside the PropertyGroup Element, add the RoleType element and mark this ASP.Net MVC project as a Web Role.

<Project ToolsVersion="3.5" DefaultTargets="Build" ...>
  <PropertyGroup>
    <RoleType>Web</RoleType>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    ...        
  </PropertyGroup>
  ...
</Project>

7. Close this project file, and reload the project.

8. Since the ASP.Net MVC now runs on the Windows Azure Service Hosting environment and will probably use its services – add a reference to Microsoft.ServiceHosting.ServiceRuntime.dll.

9. Right click the Roles node in the project tree, and add a Web Role Project in the solution. Select the ASP.Net MVC project from the project list.

Now the ASP.Net MVC project is shown as a Web Role.

10. Since the Windows Azure provides us only with the default .Net Framework 3.5 SP1 assemblies, we must make sure we also copy the ASP.Net MVC Assemblies to the cloud. To do this, right click on each of the following references of the ASP.Net MVC application, and set the Copy Local property to True:

System.Web.Abstractions
System.Web.Mvc
System.Web.Routing

That’s it. You can run the application to make sure that it is running on the Development Fabric.

Creating an ASP.Net MVC Web Role using a Project Template

Thanks to a great word done by the community, we can use a project template to do all the above steps for us. Here’s how to do this:

1. Download the project template from Codeplex at http://c4mvc.codeplex.com/.

2. Create a new project and select the Azure ASP.Net MVC template in the Community for MVC category.

This creates a new Cloud Service for Windows Azure with ASP.Net MVC Application as a Web Role.

Enjoy!

Visual Studio 2010 and .Net Framework 4.0 Beta 1 Is Publically Available

Guy Burstein — Thu, 21 May 2009 08:20:28 GMT

Visual Studio 2010 and .Net Framework 4.0 Beta 1 Is Publically Available

Downloads

Training and Resources

Enjoy!

WF/WCF using Visual Studio 2010 and .NET Framework 4 Training Kit

Guy Burstein — Tue, 19 May 2009 13:22:40 GMT

WF/WCF using Visual Studio 2010 and .NET Framework 4 Training Kit

The Microsoft WF/WCF using Visual Studio 2010 and .NET Framework 4 Training Kit includes presentations, hands-on labs, and demos. This content is designed to help you learn how to utilize the Visual Studio 2010 features and a variety of WF and WCF new features.

Learn basic workflow creation, hosting and running , and test-drive workflow development.
Get an introduction to workflow services, communication between workflows and content based correlation of workflow instances.
Use the flexibility of Flowchart workflow activities to implement non-sequential workflows.
Learn how to rehost the workflow designer in a WPF desktop application and customize it in several ways.
Learn how you can leverage some of the main WF and WCF monitoring features to track application execution and troubleshoot problems with services when necessary.
Learn how Service discovery allows you to locate services on the same subnet using ad hoc discovery, or using a proxy to establish connections with servers regardless of where they are.

This version of the training kit is compatible with Visual Studio 2010 Beta 1.

Download here.

WF 4.0: Long Running Custom Activities with Bookmarks and NativeActivity

Guy Burstein — Tue, 19 May 2009 12:37:00 GMT

WF 4.0: Long Running Custom Activities with Bookmarks and NativeActivity

This is another post in my WF 4.0: Custom Activities series. In a previous post I have talked about creating a code only custom activity that performs a simple task. In this post I’ll talk about creating a more complex activities that takes inputs from the calling program during their execution.

In the previous post WF 4.0: Code Only Custom Activities for Atomic Actions | CodeActivity, CodeActivity<T> I implemented the following activity for reading a string from the console.

public class ReadString2 : CodeActivity<string>
{
  protected override void Execute(CodeActivityContext context)
  {
    string value = Console.ReadLine();
    context.SetValue(Result, value);
  }
}

While this activity will perform the task it is meant to do, it is blocking the calling thread and bad for scalability. In addition to that It is bound to getting the value from the console only, and it is not generic enough to support another input methods.

Enter Bookmarks.

Using NativeActivity for Complex Activities

To create a long running activity, add a new item of type Workflow Element item to the project. Notice that the default activity inherits from CodeActivity.

public class ReadString3 : CodeActivity
{
  protected override void Execute(CodeActivityContext context)
  {
  }
}

To create complex activities such as long running activities, me need to change the base class and inherit from NativeActivity or NativeActivity<T>. In addition to that, there is a difference between the type of the parameter that the CodeActivity takes for the Execute method and the type that NativeActivity takes. Change the input parameter type from CodeActivityContext to ActivityExecutionContext.

public class ReadString3 : NativeActivity
{
  protected override void Execute(ActivityExecutionContext context)
  {
    throw new NotImplementedException();
  }
}

Enter Bookmarks

In previous versions of Windows Workflow Foundation we had the ExternalDataExchangeService and WorkflowQueue when we wanted to build a simple long running activity. In WF 4.0 this is much more simple to do using Bookmarks.

To use bookmarks we need to:

Create a named bookmark and Implement a callback method
Signal from the caller program

Register a Named Bookmak

The following activity registers a bookmark called “input” with a callback method called OnBookmarkCallback.

public class ReadString3 : NativeActivity
{
  OutArgument<string> name;
  public OutArgument<string> Name
  {
    get { return this.name; }
    set
    {
      ThrowIfOpen();
      this.name = value;
    }
  }
  protected override void Execute(ActivityExecutionContext context)
  {
    context.CreateNamedBookmark("input", new BookmarkCallback(this.OnBookmarkCallback));
  }
  void OnBookmarkCallback(ActivityExecutionContext context, Bookmark bookmark, object obj)
  {
    this.Name.Set(context, (string)obj);
  }
}

Signal the workflow from the caller program

In a previous post I have talked about the code that is needed to execute a workflow. Since we are now talking about long running workflows we will start with the default code that is generated for us when we create a new sequential workflow console application that uses the WorkflowInstance that lets know when the workflow instance is idle, and to resume a bookmark:

...
myInstance.Run();
//Get a string from the console and resume the bookmark called “input”
string input = Console.ReadLine();
myInstance.ResumeBookmark("input", input);
syncEvent.WaitOne(); 
... 

The main program performs the input and delivers the value to the workflow. Using this approach:

The main program is flexible in how it wants to get values from the user and any other input source
The workflow becomes idle when it is waiting for the input and during that time not consuming any resources from the machine.

To query the available bookmarks in a workflow instance, we can use the following code:

IList bookmarks = myInstance.GetAllBookmarks();
foreach (BookmarkInfo info in bookmarks)
{
  Console.Write(info.BookmarkName);
}

Enjoy!

WF 4.0: Code Only Custom Activities for Atomic Actions | CodeActivity, CodeActivity

Guy Burstein — Tue, 19 May 2009 11:00:54 GMT

WF 4.0: Code Only Custom Activities for Atomic Actions | CodeActivity, CodeActivity<T>

This is another post in my WF 4.0: Custom Activities series. In this post I’ll talk about creating a code only custom activity that performs a simple task. I’ll also use input and output parameters and talk about activities that returns a single value.

A Simple Code Activity

Lets start by building a simple activity that outputs a certain string to the console. To to that, lets add a new item of type Workflow Element (under the Workflow node in the item templates).

Visual Studio adds a new code file (remember – this is a code-only activity) with a class that inherits from the abstract class System.Activities.CodeActivity.

public class OutputString : CodeActivity
{
  protected override void Execute(CodeActivityContext context)
  {
 
  }
}

To implement the logic of the atomic action, we just have to code it here. Notice that we don’t have to tell the runtime that the status of this activity is closed or something like this like we had to in WF 3.5.

public class OutputString : CodeActivity
{
  protected override void Execute(CodeActivityContext context)
  {
    Console.WriteLine("Hello world");
  }
}

After building the project, the new custom activity will appear in the Toolbox, and can be used in the workflow.

Adding Input Parameters to the Custom Activity

To add a new input parameter to the activity, we declare a InArgument<T> field and property where T is the type of the parameter.

public class OutputString : CodeActivity
{
  InArgument<string> name;
 
  public InArgument<string> Name
  {
    get { return name; }
    set {
      ThrowIfOpen();
      name = value;
    }
  }
 
  protected override void Execute(CodeActivityContext context)
  {
    Console.WriteLine("Hello,  " + this.Name.Get(context));
  }
}

Note that in the property setter implementation I am calling the base class’ ThrowIfOpen() method. This method throws an InvalidOperationException if the activity has already been prepared for execution and the value cannot be set.

Also note that in order to get the property value, we do not store the value in a private member in the class, but instead – we use the InArgument class and using the Get method passing it the activity context.

Output Parameters to Custom Activities

Lets create a simple activity that reads the name from the console.

public class ReadString : CodeActivity
{
  OutArgument<string> outputString;
 
  public OutArgument<string> Output
  {
    get { return outputString; }
    set {
      ThrowIfOpen();
      outputString = value;
    }
  }
 
  protected override void Execute(CodeActivityContext context)
  {
    string value = Console.ReadLine();
    context.SetValue(Output, value);
  }
}

Notice how the code required for an output argument is similar to the one required for an input argument. Also notice how we set the value back to the output value using the ActivityContext instance.

Activities with a Single Output Parameter - CodeActivity<T>

The above sample read a string from the console and placed the value in the output parameter. If this is the case we can also inherit from CodeActivity<T>:

public class ReadString2 : CodeActivity<string>
{
  protected override void Execute(CodeActivityContext context)
  {
    string value = Console.ReadLine();
    context.SetValue(Result, value);
  }
}

Inheriting from CodeActivity<T> makes it more simple to write a custom activity that has a single output parameter. It has additional benefits which I’ll talk about in a subsequent post.

Summary

In this post I talked about creating a code only custom activities that performs a simple task. I have also talked about input and output parameters.

WF 4.0: Custom Activities

Guy Burstein — Tue, 19 May 2009 10:58:00 GMT

WF 4.0: Custom Activities

There are several ways to build custom activities in WF 4.0:

Xaml Based, Composite Activities
Code Based Composite Activities
Code Only Activities for Atomic Actions
Code Only Activities for Long Running Operations

In the following posts I’ll talks about each of those approaches and update the above links.

Enjoy!

WF 4.0: How to Execute a Worklflow (WorkflowInvoker vs WorkflowInstance)

Guy Burstein — Tue, 19 May 2009 09:13:56 GMT

WF 4.0: How to Execute a Worklflow (WorkflowInvoker vs WorkflowInstance)

Note: This post is based on Visual Studio 2010 Beta 1 which is the latest version available in the time of writing this post, so by the time this technology ships, there are probably things that will be slight different.

There are two ways to execute a workflow:

Using the WorkflowInstance class
Using the WorkflowInvoker class

Execute Workflows using WorkflowInstace

When you create a new Sequential Workflow Console Application, Visual Studio creates the basic code needed to execute the workflow inside the Main method:

static void Main(string[] args)
{
  AutoResetEvent syncEvent = new AutoResetEvent(false);
 
  WorkflowInstance myInstance = new WorkflowInstance(new Sequence1());
 
  myInstance.OnCompleted = delegate(WorkflowCompletedEventArgs e)
  {
    syncEvent.Set();
  };
 
  myInstance.OnUnhandledException = delegate(WorkflowUnhandledExceptionEventArgs e)
  {
    Console.WriteLine(e.UnhandledException.ToString());
    return UnhandledExceptionAction.Terminate;
  };
 
  myInstance.OnAborted = delegate(WorkflowAbortedEventArgs e)
  {
    Console.WriteLine(e.Reason);
    syncEvent.Set();
  };
 
  myInstance.Run();
 
  syncEvent.WaitOne();
 
}

1. A workflow instance is created and gets a reference to the root activity of the workflow. The WorkflowInstance class lets us control the running instance of the workflow and exposes several methods for this such as Run(), Abort(), Cancel(), Load(), Unload etc.

2. Since the workflow execution is scheduled to another thread, we need to block the main thread until the workflow is completed or terminated. To do this, we:

Create an AutoResetEvent initialized to false,
Set the event to true when the workflow is completed, and
In the main thread - wait for the workflow to complete before exiting the method.

3. In order to handle errors in the workflow such as exceptions or termination, in addition to handling the OnCompleted event, we are also handling the OnHandledException and OnAborted events. Note that when the workflow has an unhandled exception, the program can still decide how it wants to end the workflow execution, whether it is by aborting, cancelling or terminating the workflow. If the workflow is terminated, the OnCompleted event will also be raised.

Execute Workflows using WorkflowInvoker

WorkflowInvoker lets you invoke a workflow much more easily than the previous approach. It takes the instance of the workflow or activity to run and executes it synchronously.

WorkflowInvoker.Invoke(new Sequence1());

There are additional overloads of this method that takes parameters and a TimeSpan in which the workflow should complete within. I’ll talk in more details about passing parameters to workflow in a subsequent post, but in general this is all we have to know about WorkflowInvoker.

Choosing between WorkflowInstance and WorkflowInvoker

If you have a simple workflow that should run synchronously – use WorkflowInvoker. This is useful also in when unit testing workflows (more on this in a later post).

If you have a long running workflow that you want to control – persist, abort, cancel etc – use WorkflowInstance.

Enjoy!

WF 4.0: Building a Hello World Sequential Workflow

Guy Burstein — Tue, 19 May 2009 09:07:24 GMT

WF 4.0: Building a Hello World Sequential Workflow

Start Visual Studio 2010 Beta 1 and create a new Sequential Workflow Console Application.

After you click OK, visual studio creates the new projects and creates a new WF project, in which there are some things you should know about:

References:

System.Xaml – Now that there are several technologies based on Xaml, this is a new Assembly in .Net Framework 4.0 that contains Xaml services such as serialization.
System.Activities is the assembly that contains the implementation of WF 4.0, and as you can guess, the corresponding namespace is System.Activities and anything beneath it.
System.Activities.Design contains the designers for the activities and the designer re-hosting implementation. Since the new designer is based on WPF, you can also note references to WindowsBase, PresentationCode and PresentationFramework.
System.ServiceModel contains WCF implementation (as of .Net Framework 3.0) and now System.ServiceModel.Activities contains the activities used for Workflow Services (the integration between WF and WCF).

Sequence.xaml:

By default, workflows are created declaratively in WF 4.0 and represented in .xaml files with no code behind. If you open this file with an Xml editor, you will see it clearly.

<?xml version="1.0" encoding="utf-8" ?>
<p:Activity x:Class="HelloWorld.Sequence1"
          xmlns:p="http://schemas.microsoft.com/netfx/2009/xaml/activities"
          xmlns:s="clr-namespace:System;assembly=mscorlib"
          xmlns:sad="clr-namespace:System.Activities.Debugger;assembly=System.Activities"
          xmlns:sadx="clr-namespace:System.Activities.Design.Xaml;assembly=System.Activities.Design"
          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <p:Sequence sad:XamlDebuggerXmlReader.FileName="C:\...\HelloWorld\Sequence1.xaml">
 
    </p:Sequence>
</p:Activity>

The new WF Designer shows an empty sequence, representing an empty block of execution. Note the warning sign that says that the sequence has no child activities.

From the Procedural section in the Toolbox, drag the WriteLine Activity to the design surface.

Now, you get a warning that the Text property is not set. To set it, go the properties window, and open the Expression Editor. In WF 4.0 you use the Expression to set values to variables and parameters, and you can use either static values (like in this case) or VB. Yes! Expression are written in VB.

Type the text you want to display to the console and click OK.

Now, that the simple workflow is completed, you can use Ctrl + F5 to run it like you normally do.

Debugging a Workflow

The debugging experience when debugging a workflow in WF 4.0 is very similar to the debugging experience when using code. You can right click an activity the in designer and select Insert Breakpoint, or use F9 to do this.

Once you do this and run the workflow, the debugger highlights the current activity using a yellow border (similar to the yellow background for the current statement when debugging code).

Enjoy!

XAML in .Net 4.0: Attached Properties, IAttachedPropertyStore and AttachablePropertyServices

Guy Burstein — Mon, 18 May 2009 14:36:14 GMT

XAML in .Net 4.0: Attached Properties, IAttachedPropertyStore and AttachablePropertyServices

In a previous post I’ve talked about XAML Serialization and Deserialization using XamlServices in .Net Framework 4.0. In this post I’ll add to my data classes support for Attached Properties, so that they will be extensible during serialization.

Implement System.Xaml.IAttachedPropertyStore interface

This interface should be implemented by classes that can store attached properties.

public interface IAttachedPropertyStore
{
  int PropertyCount { get; }
  void CopyPropertiesTo(KeyValuePair<AttachableMemberIdentifier, object>[] array,       
                        int index);
  bool RemoveProperty(AttachableMemberIdentifier mi);
  void SetProperty(AttachableMemberIdentifier mi, object value);
  bool TryGetProperty(AttachableMemberIdentifier mi, out object value);
}

The simplest way of implementing it, is using a Dictionary<AttachableMemberIdentifier, object> that holds the attached properties. For example, the Book class from the previous post that now implements IAttachedPropertyStore:

[RuntimeNameProperty("Name")]
[ContentProperty("Related")]
public class Book : IAttachedPropertyStore
{
  public int ISBN { get; set; }
  public string Name { get; set; }
 
  private IList<Book> related = new List<Book>();
  public IList<Book> Related { get { return this.related; } }
 
  #region IAttachedPropertyStore Members
  IDictionary<AttachableMemberIdentifier, object> attachedProperties =         
      new Dictionary<AttachableMemberIdentifier, object>();
 
  public void CopyPropertiesTo(KeyValuePair<AttachableMemberIdentifier, object>[] array,
                               int index)
  {
    attachedProperties.CopyTo(array, index);
  }
 
  public int PropertyCount
  {
    get { return attachedProperties.Count; }
  }
 
  public bool RemoveProperty(AttachableMemberIdentifier member)
  {
    return attachedProperties.Remove(member);
  }
 
  public void SetProperty(AttachableMemberIdentifier member, object value)
  {
    attachedProperties[member] = value;
  }
 
  public bool TryGetProperty(AttachableMemberIdentifier member, out object value)
  {
    return attachedProperties.TryGetValue(member, out value);
  }
  #endregion
}

Use AttachablePropertyServices to Attach Properties to Stores

After adding support for Attached Properties to our object we can attach additional properties to it. This can be done directly with System.Xaml.AttachablePropertyServices class, but usually, we would prefer creating a class that provides strongly typed methods for those kinds of operations. For example, if we want to add more metadata to the book, such as an indication whether it is in stock or not we can create a class like this:

public class StockInfo
{
  public bool InStock { get; set; }
  public int Quantity { get; set; }
}

In order to store and retrieve the data from a class that implements IAttachedPropertyStore we can add the following static methods to the StockInfo class:

public class StockInfo
{
  public bool InStock { get; set; }
  public int Quantity { get; set; }
 
  public static StockInfo GetStockInfo(Book book)
  {
    StockInfo stockInfo = null;
    AttachablePropertyServices.TryGetProperty<StockInfo>(
      book,
      new AttachableMemberIdentifier(typeof(StockInfo), "StockInfo"),
      out stockInfo);
    return stockInfo;
  }
 
  public static void SetStockInfo(Book book, StockInfo stockInfo)
  {
    AttachablePropertyServices.SetProperty(
      book,
      new AttachableMemberIdentifier(typeof(StockInfo), "StockInfo"),
      stockInfo);
  }
}

Now, we can attach and retrieve the additional data from the instance:

Book book1 = new Book { Name = "First", ISBN = 123 };
StockInfo.SetStockInfo(book1, new StockInfo { InStock = true, Quantity = 27 }); 
StockInfo info = StockInfo.GetStockInfo(book1);

If we decided to serialize the instance with the attached properties assigned to it, we would get a serialized content like this:

<Book ISBN="123" Name="First" xmlns="clr-namespace:XamlSamples;assembly=XamlSamples">
  <StockInfo.StockInfo>
    <StockInfo InStock="True" Quantity="27" />
  </StockInfo.StockInfo>
</Book>

Summary

In this post I extended my data class (Book) with additional properties using the Attached Properties support in Xaml: Implementing the IAttachedPropertyStore interface by the data class and setting and getting the values using AttachablePropertyServices.

XAML in .Net 4.0: Serialization and Deserialization using XamlServices

Guy Burstein — Mon, 18 May 2009 14:30:19 GMT

XAML in .Net 4.0: Serialization and Deserialization using XamlServices

In order to serialize and deserialize using XAML in .Net Framework 4.0 we have to reference a new assembly called System.Xaml.dll. Since XAML was originally used only in WPF, some features are dependent on classes that are inside WindowsBase.dll.

Serialize to Xaml with XamlServices

Assuming we have a class called Book, that is defined like this:

public class Book
{
  public string Name { get; set; }
  public int ISBN { get; set; }
}

In order to serialize it, we use System.Xaml.XamlServices class:

Book book1 = new Book { Name = "First", ISBN = 123 };
string bookFileName = "book.xaml";
using (TextWriter writer = File.CreateText(bookFileName))
{
  XamlServices.Save(writer, book1);
}

The output file should contain the following content:

<Book ISBN="123"
    Name="My first book"
    xmlns="clr-namespace:XamlSamples;assembly=XamlSamples" />

If we have a more complex object graph, for example if each book had a list of related books:

public class Book
{
  ...
 
  private IList<Book> related = new List<Book>();
  public IList<Book> Related { get { return this.related; } }
}

Then for the following books with relations:

Book book1 = new Book { Name = "First", ISBN = 123 };
Book book2 = new Book { Name = "Second", ISBN = 456 };
Book book3 = new Book { Name = "Third", ISBN = 789 };
book1.Related.Add(book2);
book1.Related.Add(book3);
book2.Related.Add(book1);
book3.Related.Add(book1);

The result will be:

<Book x:Name="__ReferenceID0" ISBN="123" Name="First"
    xmlns="clr-namespace:XamlSamples;assembly=XamlSamples"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Book.Related>
        <Book ISBN="456" Name="Second">
            <Book.Related>
                <x:Reference>__ReferenceID0</x:Reference>
            </Book.Related>
        </Book>
        <Book ISBN="789" Name="Third">
            <Book.Related>
                <x:Reference>__ReferenceID0</x:Reference>
            </Book.Related>
        </Book>
    </Book.Related>
</Book>

Notice that the first book is now being identified using the x:Name property and its unique id is __ReferenceID0. This ID is also used to list the related books of the second book. Also note that there is no need to create a unique id to the second book because it is represented as a child element of the first one.

If we wanted to use the Name property of the books as the unique identifier, we could use the System.Windows.Markup.RuntimeNamePropertyAttribute in WindowsBase.dll:

[RuntimeNameProperty("Name")]
public class Book
{
  ...
}

Now, the output will be:

<Book ISBN="123" Name="First"
    xmlns="clr-namespace:XamlSamples;assembly=XamlSamples"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Book.Related>
        <Book ISBN="456" Name="Second">
            <Book.Related>
                <x:Reference>First</x:Reference>
            </Book.Related>
        </Book>
        <Book ISBN="789" Name="Third">
            <Book.Related>
                <x:Reference>First</x:Reference>
            </Book.Related>
        </Book>
    </Book.Related>
</Book>

Note that there is no x:Name attribute.

If we also want to take out the <Book.Related> nodes, and set its content to be the content node of the Book type, we can use the System.Windows.Markup.ContentPropertyAttribute in WindowsBase.dll.

[RuntimeNameProperty("Name")]
[ContentProperty("Related")]
public class Book
{
  ...
}

Now, the result is much simpler:

<Book ISBN="123" Name="First"
    xmlns="clr-namespace:XamlSamples;assembly=XamlSamples"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Book ISBN="456" Name="Second">
        <x:Reference>First</x:Reference>
    </Book>
    <Book ISBN="789" Name="Third">
        <x:Reference>First</x:Reference>
    </Book>
</Book>

Deserialize from Xaml with XamlServices

In order to deserialize an object graph from .xaml file, we can use XamlServices.Load method:

using (TextReader reader = File.OpenText(bookFileName))
{
  Book book = (Book)XamlServices.Load(reader);
  Console.WriteLine("Book {0} (ISBN:{1})", book.Name, book.ISBN);
  Console.WriteLine("Related Books:");
  foreach (Book relatedBook in book.Related)
  {
    Console.WriteLine("\t{0} (ISBN:{1})", relatedBook.Name, relatedBook.ISBN);
  }
}

After deserialization, the object graph is just as it was before serialization, and the output is:

Summary

In this post I showed basic samples of serialization and deserialization of object graphs uisng XamlServices in System.Xaml as part of the .Net Framework 4.0. In later post I'll talk about some more advanced features such as Attached Properties and more.