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

Workflows and the Outside World


For many workflows, an important step will be to decide how the workflow will interact with an application. How do we know if a workflow finished successfully or threw an exception? How do we get data into a workflow instance? When the workflow completes, how do we get data out? Technically, there are an infinite number of solutions to these questions. In this section, however, we are going to cover some of the fundamental techniques.

The basic mechanisms for communicating with a workflow include events, methods, and workflow parameters. An application can both raise events to a workflow instance and receive lifecycle events about a workflow instance from the workflow runtime. These lifecycle events are the first topic for discussion.

Workflow Instance Lifetime Events

The WorkflowRuntime class is the gateway to all running workflows. WorkflowRuntime exposes a number of events we can use to detect changes in a running workflow. These events are listed in the...