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

What Is a State Machine?


State machines have been around in computer science for a long time. You'll find they are especially popular in reactive systems, like the software for video games and robotics. Designers use state machines to model a system using states, events, and transitions.

A state represents a situation or circumstance. In the screenshot below, we have a state machine with two states: a Power On state and a Power Off state. The machine will always be in one of these two states.

An event is some outside stimulus. In the screenshot above, we only have one type of event, a button‑click event. The state machine will respond to this event in either the Power On or the Power Off state. Not all states have to respond to the same events.

A transition moves the state machine to the next state. A transition can only occur in response to an event. Transitions don't have to move the state machine to a new state—a transition could loop back to the same state. When the machine receives...