Essential Windows Workflow Foundation

...then get this book. This is an excellent book by the creators of WF. I had been working on WF for a long time, not just by using activities, but building them. However, I never was really confident because while I understood the concepts of activitiy, designer, validator, persistence, I was unaware of many other concepts like what is the threading model (should I make my data structures used in my custom activities thread safe?), scheduler, xoml vs xaml, etc. I used to hit these concepts while designing activities and some runtime extensions and since I didn't completely know, I did not enjoy my work as much. Then this book is released. This book is exactly what I was looking for. Concisely written, but loaded in information. More importantly, it is comprehensive. As I read from chapter to chapter, all my fears about the concepts I only half-understood were replaced by the power of a holistic knowledge of WF I was gaining. There are other books out there which tell you what a CAG activity is and how to use it, but when you are done with that kind of stuff and you don't know where to look further, read this book. With zero exaggeration, I can say that after I read the book, my confidence increased so much that I look forward to work everyday more than ever before.

This book provides an excellent overview of how the WF architecture is composed and helps advanced developers begin to think in the right frame of mind for designing and building workflow driven applications. What I found really unique is that the authors discuss the reasoning behind every feature discussed in the book. If you read it cover to cover, you'll have an excellent foundation in the unique services, threading model, and extensibility features of WF. You need to take that foundation to your IDE and MSDN and build on the concepts from the book. However, what you won't get is a bunch of examples, so if you're a code-by-example developer trying to crunch through a project, look elsewhere (try Pro WF by Bruce Bukovics). But if you are a serious architect interested in building a solution around the WF, read this book because examples won't show you how the workflow runtime manages its internal processing queues or unhandled exceptions - stuff you must understand to build the type of robust, scalable application WF is designed to create.

Briefly...I have been interested in how WF really works but even after hacking away with the betas and release versions, going to the actual early adopter meetings, and reading numerous blogs I still hadn't gotten as far with the technology as I had wanted. This book opened my eyes to the 'how' of WF and that is what I needed to get out of the woods and right into good workflow coding. Because of the descriptive details that are unfolded on how WF really works, this book seems to be for architects like myself that are required to build some complex systems based on WF. I DO think that the first chapter is awkward. It tries to explain the workflow problem domain by describing in excruciating detail how one might write a simple workflow using standard programming languages. But after getting through this chapter and into the second I realized that the first chapter was necessary for developers that don't know the problem domain at all. I still think the authors could have been more brief in chapter 1 by describing the problem domain in less detail. But the rest of the book, I believe, gives all of the most significant information that the developer community needs to really exploit the technology. Therefore, I highly recommend this work for those needing to understand how WF works and if you need to write custom activities.

I am writing this review in February 2007, and at this time there are not many options for WF related books. This book goes seriously deep into Windows Workflow Foundation concepts. The book explains important concepts beyond API calls such as Activity Oriented Programming, Resumable Program Statements, Bookmarks and many more. Beside the concepts, the book provides lots of practical solution for real life problems. For example I like the solution that this book suggests for synchronizing the Activity thread and UI threads in WinForm applications (Page 204). I read couple of negative feedbacks for this book and I can guess the reason. This book shouldn't be used to begin and learn Windows Workflow Foundation. However, you will be fascinated by this book if you already know WF well. In essence, there are resources on MSDN that help you to learn the surface of WF programs in a few days. This book is an excellent resource to take your WF knowledge into the next level.

This isn't a cookbook, if it were, it would've say so in the title. It does have plenty of examples, and quite interesting ones at that. I would recommend reading the foreword and absorbing its message before starting the book itself. The programming techniques used in WF have been around for a long time. Anyone who have ever written code in a programming language that supports continuations would find the concepts quite familiar. For me the first few chapters really helped tie the concepts of WF to what I already know. After that it was easy to understand the rest. If you don't know what continuations are, there are a lot of tutorials and attempts at explaining it on the web. Many web frameworks (Seaside, Cocoon, Uncommon web, etc) are designed around it. WF is Microsoft's crack at a continuations framework. If you know what continuations are, you will find this book very straightforward. Bookmarks = Continuations Consider only the case of single threaded execution (The WF execution model is single threaded), program execution can be thought of as a sequence of actions. In this sense it's like the pages of a book. A bookmark/continuation can be associated with each action in the sequence, so if you need to unload the program from memory (like while waiting for some event that won't happen for a while), you can store the bookmark in a database and restart from exactly where you left off, without having to flip through the previous pages.