A lot of people have written on Windows Forms and Avalon, from Michael Harsh  and Joe Stegman on the Windows Forms team to the PDC docs, to Ian Griffiths. Based on all this, I realized that it's clear that, even though we at Microsoft think we're clear about when to use each, we haven't made it clear to customers. So I took the opportunity to write something up and have it reviewed by the Avalon and Windows Forms teams. What I found most interesting about this process was how hard it was to get to a simple, memorable set of guidelines (see the bulleted list below). The interactions of the software and requirements of each development project mean that there are choices to make. In any event, I'd love feedback if you have any.

At PDC2003, Microsoft introduced a new Windows presentation technology, code-named “Avalon.” Though Avalon v1.0 is not slated to be available to customers until 2006, we want to provide guidance on the relationship of Avalon to Windows Forms to ensure that customer investments in user interface are protected.


Windows Forms has substantial customer adoption today. It delivers a powerful rapid application development experience with full integration with Visual Studio, which lowers cost of development and time to market of smart client applications. Windows Forms v2.0 will release with Visual Studio 2005 (prior to Avalon v1.0) and is the best way today to create client applications using the .NET Framework. Going forward, Windows Forms will continue to be part of the .NET Framework and supported as such and is the main way to write managed code today to prepare for Avalon.


Avalon is Microsoft’s future presentation platform, designed for creating visually stunning, differentiated user experiences. Avalon builds on top of DirectX and introduces a unified engine for creating forms-based applications, graphics, video, and documents. Avalon’s engine fully exploits the richness of today’s hardware. When delivered, Avalon will become Microsoft’s strategic UI platform.


Microsoft is committed to providing guidance, tools, and technologies that will enable customers to leverage their skills and, where appropriate, source code to extend applications with the latest technologies. One of the key areas Microsoft has invested in is interoperability between Avalon and Windows Forms, enabling Windows Forms controls to be used in Avalon applications and Avalon controls to be used in Windows Forms applications. This interoperability technology will help customers smoothly transition to Avalon.


Microsoft’s roadmap for client UI development has three main phases:


  1. Today, use Windows Forms v1.1 and observe the Microsoft Patterns and Practices guidance for maintaining clean separation between UI and other application logic.
  2. When Avalon v1.0 releases (scheduled for mid-2006), we recommend that applications looking to differentiate their user interface such as Web sites and graphically intensive applications such as complex data visualization look closely at Avalon. Other applications should continue using Windows Forms.
  3. Following the release of Avalon 1.0, the next version of Visual Studio following Visual Studio 2005 will contain tools and designers to support Avalon. At this point, customers should start to move their new development efforts to Avalon and use the Windows Forms/Avalon interoperability features.