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

Chapter 9. Rules and Conditions

Software applies knowledge to data. This is true for all software from business applications to video games. The knowledge inside software is generally a combination of procedural knowledge and declarative knowledge. Procedural knowledge is information about how to perform a task, like how to make a car and hotel reservation using an electronic travel broker. Procedural knowledge is easy to express using a general-purpose programming language like C#, Visual Basic, or any of their predecessors.

Declarative knowledge, on the other hand, is about the relationships in data. We often refer to declarative knowledge as business rules. For example, a business rule might say that hotel reservations made at least 14 days in advance receive a 10% discount, unless the cost of the room is less than $100. The date and the price share a relationship and can affect each other. Expressing this type of knowledge using a general-purpose programming language isn't difficult...