MSDN Magazine - October 2007 - (Page 66)

Shawn Wildermuth WPF Build More Responsive Apps With The Dispatcher t would be a shame if you put months of your life into creating an intuitive, natural, and even beautiful interface only to have your users tapping their fingers on their collective desks waiting for it to respond. Watching your application screech to a halt because of a long-running process is just painful. However, creating applications that are responsive takes some careful planning, which usually entails having long-running processes work in other threads so that the UI thread is free to keep up with the user. My first real experience with responsiveness goes way back to Visual C++® and MFC and the first grid I ever wrote. I was helping write a pharmacy application that had to be able to show every drug in a complex formulary. The problem was that there were 30,000 drugs, so we decided to give the appearance of responsiveness by filling the first screenful of drugs in the UI thread (in about 50 milliseconds), then using a background thread to finish filling the non-visible drugs (in about 10 seconds). The project went well and I learned the valuable lesson that user perception can be more important than reality. Windows® Presentation Foundation (WPF) is a great technology for creating compelling user interfaces, but that doesn’t mean you don’t have to take the responsiveness of your application into account. The simple fact is, no matter what type of long-running processes are involved—whether getting large results from a data66 msdnmagazine base, making asynchronous Web service calls, or any number of other potentially intensive operations—making your application more responsive is guaranteed to make your users much happier in the long run. But before you can start using an asynchronous programming model in your WPF application, it is important that you understand the WPF threading model. In this article I will not only introduce you to that threading model, but I’ll also show you how the Dispatcher-based objects work and explain how to use the BackgroundWorker so that you can create compelling and responsive user interfaces. Threads This article uses the following technologies: .NET Framework 3.0, Windows Presentation Foundation This article discusses: Threading in WPF ✥ Using the Dispatcher ✥ Non-UI thread handling ✥ Using timers ✥ Shawn Wildermuth is a Microsoft MVP, MCSD.NET, MCT, and the founder of Wildermuth Consulting Services. Shawn is also the author of Pragmatic ADO.NET (Addison-Wesley, 2002) and the coauthor of four Microsoft Certification Training Kits as well as the upcoming Prescriptive Data Architectures. He can be contacted through his Web site at wildermuthconsulting.com. http://wildermuthconsulting.com http://wildermuthconsulting.com

Table of Contents Feed for the Digital Edition of MSDN Magazine - October 2007

Cover Contents Toolbox CLR Inside Out Basic Instincts Data Points Cutting Edge Pooled Threads WPF Threads Parallel Linq Parallel Performance Mobile Apps Test Run Foundations Windows with C++ Netting C++ .NET Matters { End Bracket } Net Nuptials

MSDN Magazine - October 2007

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