Foundations of WF: an Introduction to Windows Workflow Foundation

259 Pages·2006·8.076 MB·English

by  Brian Myers

CYAN YELLOW
MAGENTA BLACK
PANTONE 123 CV
BOOKS FOR PROFESSIONALS BY PROFESSIONALS® THE EXPERT’S VOICE® IN.NET
Companion
eBook
Available
Foundations of WF: An Introduction to
Windows Workflow Foundation
F
o
Dear Reader, u
Foundations of
n
Have you ever spent hours coding workflow for your applications? If so, the new
d
Microsoft Windows Workflow Foundation (WF) technology will make your life
easier. I’ve written lots of workflow code over the years, so I can tell you from a WF
Author of experience that WF makes writing workflow code much easier. t
i
Beginning Object-Oriented In this book, you’ll discover the power of WF. You’ll learn about all the prebuild o
ASP.NET 2.0 with VB.NET activities you can include in your workflow, along with how to create your own n
activities. WF is fully extensible and allows you an unlimited number of options s
for your workflow. You’ll also learn how to use workflow activities to retrieve
o
data, and finally, how to tie an ASP.NET application with a workflow built in WF.
f
This book, unlike most of the Microsoft WF samples, has code in both VB .NET
and C#. All the examples—and there are many—have VB .NET code, and many W
have the accompanying C# code. This book will allow you to begin creating new
workflow applications easily in either VB .NET or C#. Each chapter includes an
introduction to one or more activities that make up WF, along with examples of
F
how to use each activity. Many chapters include a final section providing a real-
world example (a purchase order system). This book will have you using WF to
create workflow applications with VB .NET or C# in a short amount of time.
I hope you enjoy this new technology as much as I do.
Brian R. Myers, MCSD
An Introduction to Windows Workflow Foundation
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Myers_718-4FRONT.fm Page i Monday, September 25, 2006 6:55 AM
Foundations of WF
An Introduction to Windows
Workflow Foundation
■ ■ ■
Brian R. Myers
Myers_718-4FRONT.fm Page ii Monday, September 25, 2006 6:55 AM
Foundations of WF: An Introduction to Windows Workflow Foundation
Copyright © 2007 by Brian R. Myers
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Myers_718-4FRONT.fm Page iii Monday, September 25, 2006 6:55 AM
To my nieces (Erica, Natalie, and Sarah) and nephews (Ryan and Aaron)—
there is no limit to what you can achieve
Myers_718-4FRONT.fm Page iv Monday, September 25, 2006 6:55 AM
Myers_718-4FRONT.fm Page v Monday, September 25, 2006 6:55 AM
Contents at a Glance
About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xi
About the Technical Reviewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xiii
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
■ CHAPTER 1 Introduction to Workflow and Windows Workflow Foundation . . . 1
■ CHAPTER 2 First Workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
■ CHAPTER 3 Conditional Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
■ CHAPTER 4 Flow Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
■ CHAPTER 5 Rules-Based Workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
■ CHAPTER 6 Workflow and Web Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
■ CHAPTER 7 Interacting with Workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
■ CHAPTER 8 Custom Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
■ CHAPTER 9 Deploying Workflow Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
■ CHAPTER 10 Employee Performance Review Application . . . . . . . . . . . . . . . . . . 173
■ CHAPTER 11 Integration with Office 2007 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
■ INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
v
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Myers_718-4FRONT.fm Page vii Monday, September 25, 2006 6:55 AM
Contents
About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xi
About the Technical Reviewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xiii
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
■ CHAPTER 1 Introduction to Workflow and Windows
Workflow Foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
What Is Workflow? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
When to Use Which Workflow Type . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Why Use Workflows? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Introducing Windows Workflow Foundation . . . . . . . . . . . . . . . . . . . . . . . . 3
Architecture of Windows Workflow Foundation . . . . . . . . . . . . . . . . . . . . . . 3
Getting Started with WF and VS2005 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Out-of-the-Box Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
■ CHAPTER 2 First Workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Workflow and Activities As Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Workflow Code in VB .NET. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Workflow Code in C# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
First Workflow in VB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Sequential Workflow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Passing Parameters to VB .NET Workflow. . . . . . . . . . . . . . . . . . . . . 24
State Machine Workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
First Workflow in C# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Code Differences Between VB and C#. . . . . . . . . . . . . . . . . . . . . . . . 31
Passing Parameters to C# Workflow . . . . . . . . . . . . . . . . . . . . . . . . . 33
Real-World Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
vii
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viii ■ CONTENTS
■ CHAPTER 3 Conditional Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
IfElse Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
IfElse Activity Within Sequential Workflow. . . . . . . . . . . . . . . . . . . . . 43
IfElse Activity Within State Machine Workflow . . . . . . . . . . . . . . . . . 49
While Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
While Activity Within Sequential Workflow . . . . . . . . . . . . . . . . . . . . 53
While Activity Within State Machine Workflow . . . . . . . . . . . . . . . . . 54
Conditional Activity Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Conditional Activity Group Within Sequential Workflow. . . . . . . . . . 55
Conditional Activity Group Within State Machine Workflow. . . . . . . 57
Real-World Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
■ CHAPTER 4 Flow Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
State Machine–Specific Control Activities . . . . . . . . . . . . . . . . . . . . . . . . . 67
State-Related Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Delay, Suspend, and Terminate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Delay, Suspend, and Terminate in VB . . . . . . . . . . . . . . . . . . . . . . . . 71
Delay, Suspend, and Terminate in C# . . . . . . . . . . . . . . . . . . . . . . . . 79
Sequence and Parallel Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Sequence Workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
State Machine Workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
EventDriven Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Real-World Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
■ CHAPTER 5 Rules-Based Workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Rules in WF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Rules and the Policy Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Sequential Chaining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Full Chaining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Real-World Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
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■ CONTENTS ix
■ CHAPTER 6 Workflow and Web Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
InvokeWebService Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Workflow As Web Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
■ CHAPTER 7 Interacting with Workflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Workflow Messaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
CallExternalMethod Activity in VB. . . . . . . . . . . . . . . . . . . . . . . . . . . 117
CallExternalMethod Activity in C#. . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Events in VB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
Events in C# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Workflow Fault Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Transaction Scope and Compensate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
■ CHAPTER 8 Custom Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Basics of a Custom Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Creating a New Activity from the Activity Class . . . . . . . . . . . . . . . . . . . 141
Example in VB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Example in C#. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Real-World Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
■ CHAPTER 9 Deploying Workflow Applications . . . . . . . . . . . . . . . . . . . . . . . 163
Deployment Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Real-World Example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
ClickOnce Deployment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
SQLPersistenceService . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Implementing Persistence in VB. . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Implementing Persistence in C#. . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172