WWF(WorkFlow Foundation)

What is WorkFlow?
A simple definition would say a workflow is the series of steps, decisions, and rules needed to complete a specific task. workflow within line of business applications, user interface page-flow, document-centric workflow, human workflow, composite workflow for service oriented applications, business rule driven workflow and workflow for systems management.

wo Types of workflow is available in WWF.

· Sequential WorkFlow
· State Machine WorkFlow


What is Sequential WorkFlow?
A Sequential WorkFlow is a Top-Down process, also known as a Human Flow Process, where the activities transpire from a beginning situation and end after a predefined sequence of steps. Sequential WorkFlows are self-driven; once they are initiated, they have a totally predictable behavior throughout the execution of the activities.


What is Sequential State Machine?
The State Machine WorkFlow does not have a defined path but represents a set of states and transitions between these states. State Machine WorkFlows are event-driven: Each state can be activated after a predefined action has taken place; then, the engine executes the activities needed and stops after completion of the next state. There is no deterministic execution path between the steps because the WorkFlow does not execute in a chronological order.


WorkFlow Foundation uses a layered architecture within any application into which it is integrated It will contains three layer.

1. Model Layer
2. Runtime Layer
3. Hosting Layer

The Model Layer is the location where developers build the code to run a workflow. This layer provides the out-the-box Activities, the model for the construction of custom Activities, and the engine to build rules.

The Runtime layer ensures the execution aspects of the workflow and contains the mission-critical services required: for example, the state management and persistence service, the rules service that provides policy execution functionality, the scheduler service, and the tracking service.

The Hosting layer is the connecting link between the WorkFlow Foundation and the outside world and provides a package of services (Persistence, Timer, Tracking, Communication) needed to guarantee the control and management of the workflow.

What are the Conditions, Rules and RuleSet?

Conditions are chunks of logic that return true or false.

Rules are conditions with a set of actions to perform. Rules use a declarative if-then-else style, where the "if" is a condition to evaluate. If the condition evaluates to true, the runtime performs the "then" actions, otherwise the "else" actions.

A rule set is a collection of one or more rules.


Example Reference
http://channel9.msdn.com/posts/bruceky/Getting-started-Windows-Workflow-WF-100/
http://dotnetguts.blogspot.com/2008/02/video-tutorials-for-wwf-windows.html
WWF Resources : http://geekswithblogs.net/notesetc/articles/56260.aspx