Ok, so Silverlight is a very cool technology, and Microsoft has done a whole lot of things to make sure that it performs the way it should. They have done things like forcing you to run long running tasks, such as webservice calls, in an asynchronous fashion. But if you start doing long running tasks on your own, you need to make sure to handle the multithreading yourself. Why? Well, if you don’t, you will perform all of that stuff on the UI thread.
And why is performing heavy things on the UI thread a bad thing? Well…it just is!
Tonight, I presented a talk about MVVM “in the real world” at the Silverlight and Mobile Developer user group on Wellington.
For those of you who were there, I am sorry that it wasn’t better organized. I just ended up with way too much work the last 2 weeks, so I didn’t have enough time to structure it all enough. I decided that it was more important to get the code built than to have a lot of PowerPoint slides.
As I did promise, I you can download the code below and I have also added the IDispatchService that I talked about as well. It will give you the ability to marshal execution back to the UI thread from a ViewModel. Just call IDispatchService.BeginInvoke() and pass in a lambda expression or a method to execute on the UI thread.
For those of you who weren’t at the user group, or were there and thought that what I said was completely impossible to understand, I just want to explain what is in the download.