Windows Workflow Foundation in .NET 3.0

Introduction:
Workflow is an arrangement of work. And the way we express that is through activities, which are really fundamentally units of work, that's the building block for workflows. The first thing that Windows Workflow Foundation provides is a framework for building those activities. Out of the box a number shipped with Windows Workflow Foundation but a very important part is building activities.

WF is part of the Microsoft's new programming model .NET Framework 3.0. It enables business processes to be expressed graphically and linked directly to business logic. With WF, workflows can be expressed in either:

* Declarative XAML.
* Imperative code using any .NET targeted language.
* Developed visually through Visual Studio Designer.

The WF programming model is made up of a number of exposed APIs that are encapsulated in the Microsoft .NET Framework 3.0 namespace called System.Workflow

Workflow and its types:
In the business world, workflow is simply a business process (independent of technology) necessary to complete a task. There can be various steps involved in any business process that can be either optional or required. So simply put, "workflow" is just the flow of work.

If we add more to it, "flow of work" can be either in a sequential manner (i.e. steps are performed one after another), or there could be several points in the flow where some decisions need to be made. Since a flow cannot move from one point to another without some criteria being met, we have a state-based workflow.

Thus, we can simply say there are two types of workflow:
*Sequential
*State Machine

A state-based workflow waits on external entities to perform some action before moving on to the next step. On the other hand, a sequential workflow is just a continuous flow of operations, which might include branching, but steps in the sequential workflow don't wait for an external entity to perform the operation, and then continue.

Trends in workflow today:
First I think it is important to point out that workflow is an overloaded term it means a lot of different things to a lot of different people. Even within a development community it means a number of different things, anywhere from the rudimentary logic that you put into your program, all the way up to a full-featured business process management or a BPM solution, everything in the middle. The problem that we are trying to solve with Windows Workflow Foundation is to provide an engine upon which to build workflow-enabled applications. That are not a lot of trends around that level, we are targeting down at the framework level, targeting developers to bring to the development tool kit a workflow engine. Up in the BPM space there are all sorts of trends, in the EAI space, ESB, all these are different technologies, buzz words, which involve workflow.

Summary:
Workflow Foundation is a new workflow engine from Microsoft. Microsoft is embedding Workflow Foundation in many of its products like Office 2007, Windows Vista and soon Biztalk itself. Matt Winkler, Microsoft Technical Evangelist, walks through the story of Workflow Foundation, when to use it and the futures planned in the next version.