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

Working with Conditions


The While activity is one activity that uses a condition. The While activity will repeatedly execute its child activity until its Condition property returns false. The Properties window for the While activity allows us to set this Condition property to a Code Condition or a Declarative Rule Condition. In the screenshot below, we've told the While activity to use a code condition, and that the code condition is implemented in a method named CheckBugIndex.

Code Conditions

A code condition is an event handler in our code-beside file. A code condition returns a boolean value via a ConditionalEventArgs parameter. Because a code condition is just another method on our workflow class, the conditional logic compiles into the same assembly that hosts our workflow definition.

The implementation of CheckBugIndex is shown below. We have an array of bug objects for the workflow to process. The array might arrive as a parameter to the workflow, or through some other communication...