An Essential Windows Workflow Foundation, two WF lead architects-Dharma Shukla and Bob Schmidt-offer an under-the-hood look at the technology, explaining the why and not just the how of WF's key concepts and architecture. Serious WF developers seeking details about how to effectively utilize and extend the framework by writing activities will find cogent explanations and answers here. With simple and illustrative examples, the authors demonstrate exactly how to leverage WF's extensible programming model to craft domain-specific programs. Drawing on their unique vantage point in designing and developing WF, Shukla and Schmidt deliver authoritative coverage of * The core concepts and ideas that form the heart of WF's programming model * The execution model for activities, with details of the activity automaton, bookmarking, scheduling, and the threading model of the WF runtime * Advanced execution concepts, including activity execution contexts, transactions, persistence points, passivation, fault handling, cancellation, compensation, and synchronization * Hosting the WF runtime in applications * The activity component model, with details of validation, compilation, serialization, and visualization * Databinding, XAML, dependency properties, and WF program metadata * Declarative conditions and rules, activity designers, and designer hosting * Custom control flow patterns ranging from simple sequencing and iteration to more complex graphs and state machines * Dynamic editing of running WF program instancesEssential Windows Workflow Foundation is the definitive resource for developers seeking an in-depth understanding of this novel technology.Dharma Shukla is an architect at Microsoft working on next-generation programming models. A founding member of the Windows Workflow Foundation (WF) team, Dharma played a key role in defining the architecture of WF. Bob Schmidt is a senior program manager at Microsoft working on next-generation programming models. Since 2003, his primary focus has been on the design of WF. Both authors have been involved with the WF project since its inception, and have been responsible for specifying, designing, and developing large portions of the technology.