Book Image

Programming Windows Workflow Foundation: Practical WF Techniques and Examples using XAML and C#

By : Kenneth Scott Allen
Book Image

Programming Windows Workflow Foundation: Practical WF Techniques and Examples using XAML and C#

By: Kenneth Scott Allen

Overview of this book

Windows Workflow Foundation (WF) is a technology for defining, executing, and managing workflows. It is part of the .NET Framework 3.0 and will be available natively in the Windows Vista operating system. Windows Workflow Foundation might be the most significant piece of middleware to arrive on the Windows platform since COM+ and the Distributed Transaction Coordinator. The difference is, not every application needs a distributed transaction, but nearly every application does have a workflow encoded inside it. In this book, K Scott Allen, author of renowned .NET articles at www.odetocode.com, provides you with all the information needed to develop successful products with Windows Workflow. From the basics of how Windows Workflow can solve the difficult problems inherent in workflow solutions, through authoring workflows in code, learning about the base activity library in Windows Workflow and the different types of workflow provided, and on to building event-driven workflows using state machines, workflow communications, and finally rules and conditions in Windows Workflow, this book will give you the in-depth information you need. Throughout the book, an example "bug reporting" workflow system is developed, showcasing the technology and techniques used.
Table of Contents (14 chapters)
Programming Windows Workflow Foundation: Practical WF Techniques and Examples using XAML and C#
Credits
About the Author
About the Reviewer
Preface

State Machines in Windows Workflow


The state machine in the screenshot above is quite simple, and most systems will require a more sophisticated model. However, the concepts introduced in the screenshot (states, events, and transitions) are the same concepts we use to build state machine workflows in Windows Workflow.

In WF, the State activity represents a state in a state machine workflow. As events arrive, the workflow will transition between State activities. A state machine workflow must specify an initial state, which will be the starting state for the workflow. A state machine workflow can optionally specify a completed state. The workflow will conclude after it transitions to the completed state.

An EventDriven activity represents an event in a state machine. We place these activities inside State activities to represent the legal events for the state. Inside an EventDriven activity, we can place a sequence of activities that will execute when the event arrives. The last activity in...