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

Fault Handling


Although fault handling is arguably a type of control flow, this section is dedicated to these activities so we can dive in with more detail. Fault handling in Windows Workflow handles exceptions that occur during execution. We can catch exceptions with fault handlers and perhaps try to recover from the error. We might try to

compensate for a committed transaction, or send an alert to an administrative email address and wait for a missing file to reappear.

It is always a bad idea to blindly handle faults if we don't have a recovery plan. This is akin to swallowing exceptions in C# or Visual Basic. If the workflow throws an exception that we don't know how to handle, it is best to let the exception run its course and have the runtime terminate the workflow.

The FaultHandlersActivity

The FaultHandlers activity isn't an activity we can drag from the Toolbox into the workflow designer. Instead, the workflow designer will provide the activity for us when the condition is right...