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

Inspecting State Machines


Think about the user interface that we want to provide for our bug-tracking service. We wouldn't want to give the user the option to create exceptions. For instance, we wouldn't want to offer a Close This Bug button when the bug is in a state that will not transition to the closed state. Instead, we want the user interface to reflect the current state of the bug and only allow the user to perform legal actions. We can do this with the help of the StateMachineWorkflowInstance class.

StateMachineWorkflowInstance

The StateMachineWorkflowInstance class provides an API for us to manage and query a state machine workflow. As shown in the class diagram in the screenshot below, this API includes properties we can use to fetch the current state name and find the legal transitions for the state. The class also includes a method to set the state of the state machine. Although we generally want the bug to follow the workflow we've designed in our state machine, we could use the...