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

The Workflow Runtime


We've used the runtime in previous chapters, but let's review what we've learned so far. The WorkflowRuntime class is the host's gateway to Windows Workflow. A host creates an instance of the class, and then subscribes to one or more of the events mentioned in the table below. These events report state changes for all workflow instances that the runtime is executing.

Name

Occurs

WorkflowAborted

When an instance aborts

WorkflowCompleted

When the instance completes

WorkflowCreated

When a successful call to CreateWorkflow completes

WorkflowIdled

When a workflow enters an idle state

WorkflowLoaded

When a persistence service restores a workflow instance

WorkflowPersisted

When a persistence service saves a workflow

WorkflowResumed

When workflow execution continues after a suspension

WorkflowStarted

When a workflow firsts starts execution

The code required to create the runtime and subscribe to events is relatively straightforward. The following example creates...