Sometimes I wonder... Other times I know.
Wednesday, March 22, 2006
 
VC hit & misses
It is not very often a VC company will disclose the companies it passes on, especially when those companies happen to be wildly successful. However, Bessemer Venture posted a list of serveral investmnet opportunities it declined over the years. Quite amusing read..

- posted by # posted by Dennis Pilarinos : 3:07 PM 2 comments  
Sunday, March 12, 2006
 
Nate Talbert opens shop...
If you're looking for answers to questions like:
  • What happens to a workflow instance I have created but never started?
  • How do I get access to a transaction inside my workflow?
  • Does a ParallelActivity start one thread for each branch? How many threads will it use for processing?
  • How do I manage resources (like sockets) which are held by an activity?
Then without question, go checkout Nate's blog titled "Advanced Workflow: Enabling Tricky Scenarios"... without question, he's one of the best resources for these types of questions...

- posted by # posted by Dennis Pilarinos : 11:40 PM 0 comments  
Wednesday, March 08, 2006
 
Potentially the greatest AJAX UI ever built...
I've been reading about and writing a bunch of AJAX code recently. I thought I'd gotten the hang of it. The new Windows Live looks really good, however, Scott believes he's created the great AJAX UI ever built...

- posted by # posted by Dennis Pilarinos : 10:51 PM 0 comments  
Monday, March 06, 2006
 
Getting up to speed on WF Rules
Jurgen Willis has written an excellent article on the rules capabilities included in WF v1.0. He is, without question, "Mr. Rules" at Microsoft.

From him directly... "If you are working with customers/partners who are new to the rules features, you can point them there to help get them started"

- posted by # posted by Dennis Pilarinos : 10:28 AM 0 comments  
Sunday, March 05, 2006
 
The Simpsons...
The Sun reports that the show's creators filmed the show's opening using real actors.. here is a link to the video.

- posted by # posted by Dennis Pilarinos : 12:02 PM 0 comments  
Friday, March 03, 2006
 
Getting DependencyProperty RegisterAttached properties to appear in the Property Browser redux
I posted an earlier entry on this topic, but deleted it for this entry instead. I hope to clarify a few questions and correct some of the code as well (thanks Dharma and Akash).

Back again with another frequently asked question on our internal discussion alias (and a tester also opened a bug for a sample on how to do this).

This time, we're going to look at how activities can project their properties to their children through DependencyProperty.RegisterAttached and the work involved to have them show up in the Visual Studio property browser.

To see an example of this in WF, drag a Conditioned Activity Group on to the design surface and add a child activity (like a code activity). Notice that in addition to the child activity's properties (Execute Code), a "WhenCondition" has been added to the child. Fire up Lutz's reflector and you'll see that "WhenCondition" is a Dependency Property on the CAG.

We're going to use System.ComponentModel.IExtenderProvider to provide the logic of extending the activities properties to the children in the property browser. There numerous articles which talk about IExtenderProvider, but I thought it'd be useful to give an example within the context of WF.

There are three types we need to define: the activity, the implementation of IExtenderProvider and the activity designer which ties them both together.

Lets start by launching Visual Studio, creating a new Activity Library and defining a new dependency property. To expedite matters, use the workflow code snippets and change the "Register" method to "RegisterAttached".

For the purpose of this sample, the parent activity will project a property onto its children. Thus, the standard get/set methods which would define the property on the parent are not needed.

However, since the child activity inherits the properties from the parent (versus having the property defined directly) the parent needs to provide a way for the child to get/set values. Thus, we define two statics which accomplish the get/set semantics.



Now, lets create a new class which will implement IExtenderProvider. I'd recommend reading the article written by James Johnson to get up to speed, but I'll provide a coles notes version


  • The IExtenderProvider interface only has one method, bool CanExtend(object). This method tells the designer whether the extended properties should be displayed for the given object. This interface has no information about the properties as the designer gets the properties by looking for the ProvideProperty attribute on the component implementing IExtenderProvider. This method should return true to have the designer use reflection to begin looking for the extended properties
  • The ProvideProperty attribute specifies the property name as well as the type of objects it can be applied to
  • Once you have the attribute added you need to write two public methods, these methods act as the Get/Set parts of a property and are named Get and Set. The Get method takes in a type of the kind the ProvideProperty attribute defines and returns the data type of the property. The Set method takes two arguments, the first is of the type of specified in the ProvideProperty attribute, the second is of the same data type as the Get returns, this is the value the user wishes to set the property to

Following these notes you'll end up with a class which should look like this:





Finally, we need to create a designer for this activity. Activity designers define the visual representation and behavior of the activity, thus, we can tie together the ExtenderProvider and Activity class through the designer (remember to attribute your activity with [Designer(..)]). The logic to add the ExtenderProvider is defined within the Initialize method.





Now, we can test our work out by adding a Workflow Console Application to the solution. Drag the custom activity onto the design surface and drag a code shape into the custom activity.




As you'd expect, inspecting the Property Browser shows a "Child" property which appears on the Code activity.



To test that the GetChildProperty method works, define a handler for the Code Activity and try out the code below.




Here's the code for this sample..

- posted by # posted by Dennis Pilarinos : 10:11 AM 0 comments  
Thursday, March 02, 2006
 
Understanding the Lifecycle of a Workflow
Moustafa has just posted a great entry on workflow instance level events, operations and workflow persistence. I highly recommend reading and bookmarking that page. I promise you'll end up referring to it :)

- posted by # posted by Dennis Pilarinos : 11:07 PM 0 comments  
Wednesday, March 01, 2006
 
Code Snippets
As most software developers know, the realities of shipping often require you to prioritize and cut features to make dates or quality metrics.

To this extent, we had to cut the property definition dialog from the custom activity designer. As the feature owner, I had to make sure you would still have a way to quickly create Dependency Properties & EventHandlers on your custom activities. To do so, I wrote 4 Code Snippets for C# and VB.NET.

Code Snippets are reusable, task-oriented blocks of code that help you automate generation of members, methods and the like. In order to invoke them, you can you can right click in the C# or VB.NET editor and select "Insert Snippet"

In C#, you will now see a "Workflow" category as part of the default snippets (as shown below)... This is also supported in VB.







There are numerous tools which help you create code snippets and a couple of websites which help you create and find code snippets.

For those 3rd party Visual Studio developers, the way to get your category to appear "by default" (instead of requiring a developer to use the Code Snippet Manager) is to set the following registry keys (thanks to Meghan Perez)

Within HKLM\Software\Microsoft\VisualStudio\8.0\Languages\CodeExpansions\ navigate to the "Paths" of the language you would like the snippets to appear in. Create new string keys and assign the value to the path of the directory which contains the snippets. It is important to note that the name of the last folder in the path defines what will appear in the Snippet Intellisense picker.

It is fairly trivial to create and distribute Code Snippets and clearly helps you template commonly used code. I spent more time getting the snippets incorporated into the Windows Workflow Foundation setup and build process than I did writing them!

- posted by # posted by Dennis Pilarinos : 10:47 AM 1 comments