This chapter gives you an overview of how business applications were and are traditionally developed,... more

This chapter gives you an overview of how business applications were and are traditionally developed, as well as an introduction to workflow and the Windows Workflow Foundation platform.

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This chapter introduces you to the Windows Workflow Foundation development environment that is Visual Studio 2005.... more

This chapter introduces you to the Windows Workflow Foundation development environment that is Visual Studio 2005. You develop a simple Hello World application that highlights several core pieces of a workflow.

The topics included in this chapter are as follows:

• Developing workflows in Visual Studio 2005

• Calling a workflow from a console application

• Simple workflow communications with parameters

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This chapter introduces you to the individual components of Windows Workflow Foundation at a high level.... more

This chapter introduces you to the individual components of Windows Workflow Foundation at a high level. (Subsequent chapters dig into further detail on each topic.) This chapter also discusses a few areas of interest related to the Windows Workflow Foundation platform, such as extensibility and other technologies that affect workflow—for example, BizTalk and SharePoint.

Topics covered in this chapter include the following:

• Workflow types

• Components of Windows Workflow Foundation

• Windows Workflow characteristics

• Windows Workflow and other technologies

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This chapter covers the core concepts of workflow development, including the workflow infrastructure,... more

This chapter covers the core concepts of workflow development, including the workflow infrastructure, compilation, serialization, and development modes. It also discusses the Visual Studio development environment. As a key component of the workflow development process, Visual Studio provides a rich set of tools for developing and debugging workflow-based applications.

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Workflows need a host application to run. The host is responsible for starting and maintaining workflows—the workflow... more

Workflows need a host application to run. The host is responsible for starting and maintaining workflows—the workflow itself doesn’t need to know anything about the infrastructure in which it is running. However, this infrastructure is very important to the lifecycle of workflows.

Part of the concept of hosting is workflow communication. Workflows need to be able to communicate important information to the outside world, and vice versa. Windows Workflow Foundation provides the necessary components and architecture to facilitate this communication.

This chapter covers the following topics:

• Workflow hosting

• Workflow runtime

• Workflow and runtime management

• Workflow communication methods

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This chapter covers the workflow building blocks—activities. First, the chapter provides an overview of the activity... more

This chapter covers the workflow building blocks—activities. First, the chapter provides an overview of the activity architecture and relevant components of Windows Workflow Foundation. After that, the chapter presents a detailed list and discussion of each out-of-the-box activity. The chapter names each activity, and discusses important relationships between it and other activities.

The second half of the chapter covers custom activity development. The chapter describes pertinent steps and pitfalls related to creating new activities and provides examples to illustrate the text.

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This chapter covers the runtime services architecture within Windows Workflow Foundation. The Workflow API defines the... more

This chapter covers the runtime services architecture within Windows Workflow Foundation. The Workflow API defines the base infrastructure for several runtime service types, including workflow persistence and tracking. In addition, several out-of-the-box services implement the base infrastructure. These services and examples of each can be found in this chapter.

The second half of the chapter covers custom runtime service development. The chapter covers alternatives to the out-of-the-box services and how to extend the base framework ,and provides examples that illustrate how to develop custom services.

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The previous chapter introduces a lot of the core concepts related to Windows Workflow Foundation activities,... more

The previous chapter introduces a lot of the core concepts related to Windows Workflow Foundation activities, such as key classes and the activity execution model. However, these topics just scratched the surface of the depth of activity concepts. This chapter introduces you to some of the more advanced activity themes, such as activity types, and takes a closer look at activity execution and communication.

This chapter covers the following topics:

• The activity execution model

• Activity execution contexts

• Iterative activities

• Event activities

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Business rules are a crucial part of most software systems because they allow the translation of real business requirements... more

Business rules are a crucial part of most software systems because they allow the translation of real business requirements to executable code. Many times business rules are treated as second-class citizens when they are simply lumped in with all the rest of the code that makes up an application. Because businesses can change over time, optimally you should be able to change business rules in a more eloquent way than just tweaking and redeploying the code it.

In addition, you may find that some implementations of business rules are looser or tighter than others. For example, there are well-known algorithms for evaluating rules in a set. A couple of these are the Rete algorithm and sequential algorithms. Plenty of resources on the Web discuss the semantics of business rules and various algorithms along with their pros and cons. The purpose of this chapter is to cover the rules implementation in Windows Workflow Foundation, so other extraneous information is kept to a minimum.

To some people, business rules are simply if-else statements in code that loosely tie to some business requirement. Luckily, in Windows Workflow Foundation, rules are much more than this.

The following topics are covered in this chapter:

• Code conditions

• Declarative rule conditions

• Rule sets

• Chaining

• Rules development

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This chapter covers a distinct type of workflow: the state machine. Although this workflow type has already been introduced... more

This chapter covers a distinct type of workflow: the state machine. Although this workflow type has already been introduced to you, the sequential workflow tends to steal the spotlight. There is not really a reason for this except for the fact that most people tend to think of a sequential process when thinking of workflow. With that said, the state machine is no less important or useful when modeling processes.

Topics covered in this chapter include the following:

• Traits of a state-machine workflow

• When to use the state machine

• State-machine activities

• Developing state-machine workflows

• Advanced topics

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This chapter discusses a few advanced topics that are in some ways related. First, the chapter covers the concept of dynamic... more

This chapter discusses a few advanced topics that are in some ways related. First, the chapter covers the concept of dynamic update. Dynamic update enables you to modify the behavior of a workflow instance after it has started. The other topic is designer re-hosting, which enables you to include the rich Visual Studio workflow views in your own custom applications.

Although each topic has its own distinct functionality in Windows Workflow Foundation, you can use them together to provide a great deal of functionality in end-user applications.

This chapter covers the following topics:

• Dynamic update concepts and drivers

• Dynamic update infrastructure

• The workflow designer

• Hosting the designer in custom applications

• Applying dynamic update and designer re-hosting

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This chapter is basically about what to do when things go wrong in your workflows. The major topics are exceptions and... more

This chapter is basically about what to do when things go wrong in your workflows. The major topics are exceptions and exception handling, workflow faults, and the debugging of workflows. This chapter explains the following areas in detail:

• Exceptions and the workflow runtime

• Common exception-handling techniques

• Debugging, troubleshooting, and diagnostics

• The Visual Studio debugging infrastructure

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With the release of ASP.NET in 2002, Microsoft took web development to the next level by providing an object-oriented... more

With the release of ASP.NET in 2002, Microsoft took web development to the next level by providing an object-oriented way to develop web applications in an extremely rapid manner. And as you know by now, Windows Workflow Foundation also provides a new method of architecting applications. You can use these two technologies together to enable new types of systems.

This chapter covers the following topics regarding the use of ASP.NET with Windows Workflow Foundation:

• Various application scenarios

• Pitfalls of using ASP.NET with workflows

• Hosting Windows Workflow Foundation in an ASP.NET environment

• Using a workflow as a page flow engine

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This chapter is about how workflows relates to connected systems. Workflows sometimes need to talk to the outside world,... more

This chapter is about how workflows relates to connected systems. Workflows sometimes need to talk to the outside world, and conversely, the outside world may need a way to call in to a workflow. Web services can serve as a great way to provide widespread communications in software; therefore, this chapter includes an in-depth discussion of these services.

In addition, there are architectural issues that you need to consider before applying workflow and web services in your organization. Services-oriented architecture (SOA) has been a very popular buzzword in recent years, and when studied and applied sensibly, it can greatly enhance a company’s ability to componentize software and become more agile.

This chapter also covers a new Microsoft technology referred to as Windows Communication Foundation (WCF). WCF encompasses a great deal of functionality related to developing connected systems, and not just around standard web services. You can also use WCF in conjunction with Windows Workflow Foundation to expose workflow functionality outside the bounds of a single application.

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This chapter introduces the Microsoft Office system and shows how workflow plays into its technologies.... more

This chapter introduces the Microsoft Office system and shows how workflow plays into its technologies. With the advent of Microsoft Office 2007, workflow is a large part of the new feature set. Up to this point, this book has covered workflow development in the context of developing solutions from scratch. Although custom solutions definitely have their place in the world, extending and using existing technologies such as the Microsoft Office system, where it makes sense, can provide a great deal of time and cost savings.

This chapter covers the following topics:

• The components of Microsoft Office

• Collaboration with Microsoft SharePoint

• How workflow fits into Office and SharePoint

• Office and SharePoint development scenarios

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