Windows Workflow Foundation (WF) is one of the four technological "pillars" of the .Net Framework 3.0 release. It is deeply integrated in a host of Microsoft products such as Exchange, SharePoint, SQL Server 2005, and the Vista operating system. As you can imagine, the topic is very broad and deep. I have begun speaking to local user groups in the Atlanta area about WF, and it is difficult to cover the depth and breadth of this topic in a one hour overview.
Based on feedback from my presentations, there definitely is a need for an introductory WF book which discusses several of the key concepts, that might not be covered sufficiently in a one hour lecture. In my opinion, Foundations of WF by Brian R. Myers (Apress, 2007) fills this niche.
The target audience is the developer who is just getting started with WF. Because the product was just recently released - this includes just about everyone! The book is written with a focus on the VB .Net programmer which is unusual because most of the SDK (software development kit) samples that are available are primarily written in C#. I would, however, recommend the book to both VB .Net and C# programmers, because many of the source code samples available for download are also available in C#. The complete source code, however, is only available in VB .Net. The book is clearly written, and the author explains what the focus for each chapters is, and why the concept is important.
Some of the chapters of the book that I thought were very helpful were those dealing with rules (Chapter 5), conditional activites (Chapter 3), flow activities (Chapter 4), and one that discussed persistence (Chapter 9). There also were examples of 'real world' examples such as a purchase order system, and an employee review system, that reinforced the concepts that were introduced in each chapter. The author also does a good job of pointing out the differences between writing a workflow in Visual Studio .Net using VB .Net versus C# (Chapter 2), which are mostly syntactical in nature.
I felt that the chapter dealing with WF and web services (Chapter 6) was too brief and could have included additional detail. In addition, in several chapters, some of the data validation code in the "real world examples" was not robust enough to be considered "ready for prime time". Noticeably absent, was the use of TryParse or a similar algorithm to check for correct data types. Some of the source code available for download also contained errors so I was not able to test all of the code examples end to end. There also were several typos,and the book still refers to the WF SDK, WinFX, and SharePoint Portal Server. These names are now referred to as the Windows SDK, .Net Framework 3.0, and MOSS Server respectively.
Overall, I think the book is a very good introduction to WF and I would recommend the book to the software developer who is looking for more than the "50,000" foot view of WF. It contains code samples in every chapter, which do a good job of reinforcing the concepts contained in each chapter. It also clarifies a lot of crucial material that doesn't really get explained sufficiently when doing the hands-on-labs available for download from Microsoft.
