Two Chefs in the Kitchen: The future of Silverlight with HTML 5

I have heard, and participated in, the HTML 5 vs. Silverlight argument. Often the dialog begins with something like “Silverlight is on deaths door, HTML 5 has fatally wounded Silverlight and it will officially become a corpse in the very near future”. I could not disagree more.

I do not see HTML 5 as a competitor to Silverlight. While they share some of the same abilities, to me they seem more like two chefs in a single kitchen: both can produce glorious meals simultaneously in different (or the same) ways, both can choose to work together to create a single unified experience or choose to do their own thing, merely existing within the same space at the same time.

Today the Silverlight Team blogged about The Future of Silverlight and how HTML 5 will play a role in that future

On the web, the purpose of Silverlight has never been to replace HTML; it’s to do the things that HTML (and other technologies) couldn’t in a way that was easy for developers to tap into. Microsoft remains committed to using Silverlight to extend the web by enabling scenarios that HTML doesn’t cover. From simple “islands of richness” in HTML pages to full desktop-like applications in the browser and beyond, Silverlight enables applications that deliver the kinds of rich experiences users want. We group these into three broad categories: premium media experiences, consumer apps and games, and business/enterprise apps.

I encourage you to Read the Entire Article and Subscribe to the Silverlight Team Blog. In my opinion Silverlight is here to stay, its a solid viable technology, and I am committed to continuing to use it to solve real world problems as I build software.

In this discussion of the future of Silverlight, there’s a critical point that is sometimes overlooked as Silverlight is still often referred to—even by Microsoft—as a browser plug-in. The web is evolving and Silverlight is evolving, too. Although applications running inside a web browser remain a focus for us, two years ago we began showing how Silverlight is much more than a browser technology.

Error: The default XML namespace of the project must be the MSBuild XML namespace

One day you get to work, your boss tells you that there is a project that he needs you to work on, you get the code from source control and open the project up in Visual Studio.NET

During project loading you get a series of crazy errors you have never seen before, ultimately ending in:

error : Unable to read the project file '.csproj'. .csproj(2,1): The default XML namespace of the project must be the MSBuild XML namespace. If the project is authored in the MSBuild 2003 format, please add xmlns="" to the element. If the project has been authored in the old 1.0 or 1.2 format, please convert it to MSBuild 2003 format.

You scratch your head, with a big thought cloud overhead that reads “WTF???”


You notice that the Silverlight project (in my case the project’s called “SilverlightInterface”) failed to load and is “unavailable” in Solution Explorer:


So you try to “reload” it by right clicking on the (currently unavailable) project and selecting “Reload Project” from the menu, only to get an even nastier error message:


Looking at the Output Window you’re faced with a never-before-seen error which states something about the The default XML namespace of the project must be the MSBuild XML namespace.

Fortunately the solution is simple:

  1. In Windows Explorer navigate to the project
  2. Right Click on the .cproj file, select Properties, and un-check the “Read Only” checkbox
  3. Open up the .cproj file in Notepad
  4. On line 2 change xmlns=”″ to xmlns=”″ (notice this only difference is we changed 2008 to 2003)
  5. Save your changes
  6. In Visual Studio right click on the (currently unavailable) project and select “Reload Project”
  7. The project will now load normally and you can get on with your life

Error: Could not load file or assembly System.Windows.Interactivity

Silverlight 4 and Visual Studio.NET 2010 are awesome, however if you are required to create a Silverlight 3 application and currently are using Visual Studio.NET 2010 than the default target for your Silverlight app will be version 4. You will have to go into the Properties panel for the Silverlight app and change its target to point to SL 3.


While this is usually not an issue occasionally you may run into a deceiving error message. The project builds fine, you check the reference to the System.Windows.Interactivity assembly and it does exist, however when you go to view the XAML in the designer (either in VS or in Blend) you get the following error:




This is caused when your SL 3 app references any assembly that targets a newer version, for example Microsoft.Expression.Prototyping.Interactivity.dll or Microsoft.Expression.Interactions.dll that are found in Blend 4.



Removing the references to these assemblies will resolve the issue.


There is never only “one right way” to develop something

A great statement from Scott Guthrie in his article entitled About Technical Debates

There is never only “one right way” to develop something. As an opening interview question I sometimes ask people to sort an array of numbers in the most efficient way they can. Most people don’t do well with it.

This is usually not because they don’t know sort algorithms, but rather because they never think to ask the scenarios and requirements behind it – which is critical to understanding the most efficient way to do it. How big is the sequence of numbers? How random is the typical number sequence (is it sometimes already mostly sorted, how big is the spread of numbers, are the numbers all unique, do duplicates cluster together)? How parallel is the computer architecture? Can you allocate memory as part of the sort or must it be constant? Etc.

These are important questions to ask because the most efficient and optimal way to sort an array of numbers depends on understanding the answers

Error: This assembly may have been downloaded from the Web

If you’re like most programmers you get a LOT of stuff from the Internet, like sample projects, assembly’s (i.e. .DLL’s), etc… It seems like just about everything we do these days in software is somehow related to the Web, even if that means you are just blogging about it.

After upgrading a Silverlight project so that it can be developed on Visual Studio.NET 2010 I ran into a show-stopper error:

Could not load the assembly file:///.... .dll. This assembly may have been downloaded from the Web. If an assembly has been downloaded from the Web, it is flagged by Windows as being a Web file, even if it resides on the local computer. This may prevent it from being used in your project. You can change this designation by changing the file properties. Only unblock assemblies that you trust. See for more information.


The recommended solution is to “Unblock” the content through Windows Explorer, the only problem is that I was developing this application on a machine at my work and that machine’s Security Settings prevented the “Unblock” feature from Windows Explorer (you couldn’t even see the Unblock button), I thought I was totally screwed.

frustration After banging my head on the desk a few thousand times a co-worker finally suggested that I copy the DLL’s to a Fat32 drive (like an external Thumb drive), then copy them back to the orginal location (over-writing the originals with the copy).

I then simply needed to select “View All Files” for the project in Visual Studio, expand the Bin directory, and delete all the contents (I also removed the reference to the DLL and re-added it just to be safe).

Recompiling the project was successful and I could finally get back to work, what a pain in the a—, hope this helps you fix this issue if you run into it

Databind Options in Silverlight: Pros and Cons of each

Recently I read an article by Sean Wildermuth concering the State of Data Access in Silverlight 4. He provided an excellent chart outlining the Pros and Cons of each data access choice.

I encourage you to read the article, and subscribe to Sean’s blog, as it provides some valuable insite. I think this statement sums things up quite nicely:

The three options for data access are still the same “Web Services, WCF Data Services and WCF RIA Services”. My major issue with data access today in Silverlight persists: there is no perfect answer. There is give and take with each approach and giving good advice about the right one is difficult.

Sean also provided a very nice chart that quickly outlines these options:


Rethinking the IDE: Coding with Bubbles

Code Bubbles
Rethinking the User Interface Paradigm of Integrated Development Environments
This innovative way of working with code comes from Andrew Bragdon in the Department of Computer Science at Brown University.

Developers spend significant time reading and navigating code fragments spread across multiple locations. The file-based nature of contemporary IDEs makes it prohibitively difficult to create and maintain a simultaneous view of such fragments. We propose a novel user interface metaphor for code understanding and maintanence based on collections of lightweight, editable fragments called bubbles, which form concurrently visible working sets.

The essential goal of this project is to make it easier for developers to see many fragments of code (or other information) at once without having to navigate back and forth. Each of these fragments is shown in a bubble.

A bubble is a fully editable and interactive view of a fragment such as a method or collection of member variables. Bubbles, in contrast to windows, have minimal border decoration, avoid clipping their contents by using automatic code reflow and elision, and do not overlap but instead push each other out of the way. Bubbles exist in a large, pannable 2-D virtual space where a cluster of bubbles comprises a concurrently visible working set. Bubbles support a lightweight grouping mechanism, and further support connections between them.

A quantiative user study indicates that Code Bubbles increased performance significantly for two controlled code understanding tasks. A qualitative user study with 23 professional developers indicates substantial interest and enthusiasm for the approach, despite the radical departure from what developers are used to.

Its all about the development team

In this fascinating talk given by Ed Catmull, a founding member of PIXAR, he provides critical insight into the success and failures of teams of people and companies as a whole. You should really watch the entire talk, it is well worth your time.

Growing stronger by stretching yourself

Another great statement from Scott Guthrie

Developers (good and bad) can grow stronger by stretching themselves and learning new ideas and approaches. Even if they ultimately don’t use something new directly, the act of learning it can sharpen them in positive ways.

Change is constant in the technology industry. Change can be scary. Whether you get overwhelmed by change, though, ultimately comes down to whether you let yourself be overwhelmed. Don’t stress about having to stop and suddenly learn a bunch of new things – rarely do you have to.

The best approach to avoid being overwhelmed is to be pragmatic, stay reasonably informed about a broad set of things at a high-level (not just technologies and tools but also methodologies), and have the confidence to know that if it is important to learn a new technology, then your existing development skills will mostly transition and help. Syntax and APIs are rarely the most important thing anyway when it comes to development – problem solving, customer empathy/engagement, and the ability to stay focused and disciplined on a project are much more valuable.