February, 2010

We’ve been hard at work here in Redmond (and with our team in Shanghai) working on getting WF ready for release.  We’ve made a ton of progress in the RC build that was made available yesterday , please download it and check it out.  Also, and in important bold text, if you have feedback, please, please, please file an issue on Connect so that the team can look at it right away.   One thing that I want to point out about Connect is that it is not a vacuum, the entries there go directly...

Oh, the imports designer . This innocuous looking piece of UI packs a lot of functionality in a little designer. You would think that this designer should be pretty straightforward. The original concept of this feature was that this would simply be the place to manage namespaces, much in the same way you would manage using statements or imports statements. You add a namespace to the designer, and then you can use the short name of types in that namespace in expressions. The Imports designer does...

Today the RC version of Visual Studio was made publically available for MSDN subscribers. See the VS RC page for download details. We got a ton of bug fixes and perf improvements in for RC. Go download this and play with it, it’s a big improvement from beta 2. With the RC release, we also released the vast majority of the WF designer documentation. Here are the highlights: WF designer landing page Using the WF activity designers Using the expression editor and the Imports designer Keyboard shortcuts...

In the Workflow Designer, all input provided to the workflow must be valid according to the model before the workflow can be serialized*. This has a number of implications that you see throughout the designer, like: TryCatch designer – must select a non-duplicate exception before you can continue, can’t have empty rows Switch<T> designer – switch cases must be unique Generic activities – must close the type before serializing Variables – can’t have duplicate variable names in the same scope...

Workflow Foundation Internals (III) Andrew Au Continue with our last article, we will work on allowing parallelism and create the workflow/host communication pattern. This pattern is actually very common, such as waiting for multiple approvers to approve a document. Last time we notice the problem is that ScheduleActivity can only be called once, so the most obvious solution is to allow multiple delegates to be put in the states. Looking at states.Frames, it is a stack and we access the top of the...

Workflow Foundation Internals (II) Andrew Au Continue with our last article, we will work on separating program and data. Program and data are very distinct concepts from the perspective of a programmer. For example, you can run code, but you can’t run data. Code are not expected to be changed during runtime (except some circumstances such as hook or overlay), but data are expected to be changed all the time. From the processor’s perspective, they are no different. They are just some bytes. From...

Workflow Foundation Internals (I) Andrew Au Inspired by the book Essential Windows Workflow Foundation that describes the last version of Workflow Foundation, I can’t stop myself trying to write an equivalent piece for WF4. While the basic working principle is fundamentally the same, the programming model is quite different. We will start from the same principle of using serialization of delegate, and we will develop our ‘home-made’ workflow runtime, and we will see how WF4 made its design decisions...