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

Faults


Of course, a workflow might not execute flawlessly. Unexpected exceptions may arise because a database server might not be available, for instance. We can also intentionally raise an exception with a ThrowActivity.

Managing exceptions inside a workflow is similar to managing exceptions in Visual Basic or C#. Composite activities can include fault handlers to catch exceptions. If an activity does not handle an exception that occurs, the runtime will let the exception propagate to the parent activity. This is similar to an exception moving up the call stack until the .NET runtime can locate an appropriate exception handler. If the runtime does not find a catch handler for a .NET application thread, the application terminates. If an exception occurs inside a workflow, and the runtime can find no fault handler to catch the exception, the runtime terminates the workflow and raises the WorkflowTerminated event.

The FaultHandlerActivity handles exceptions in Windows Workflow. We can view...