Building Applications with Windows Workflow Foundation
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In this second part of a three-part series, you'll see how Windows Workflow Foundation (WF) helps you to build workflow-based applications. It is excerpted from chapter four of the book
Building a Web 2.0 Portal with ASP.NET 3.5, written by Omar Al Zabir (O'Reilly, 2008; ISBN: 0596510500). Copyright © 2008 O'Reilly Media, Inc. All rights reserved. Used with permission from the publisher. Available from booksellers or direct from O'Reilly Media.
Introducing Windows Workflow Foundation
Windows Workflow Foundation (WF), included in .NET 3.0, provides the programming model, engine, and tools for quickly building workflow-enabled applications. It gives developers the ability to model business processes in a visual designer by drawing flow chart diagrams. Complex business operations can be modeled as a workflow in the visual workflow designer included in Visual Studio 2008, and coded using any .NET programming language. WF consists of the following parts:
Activity model
Activities are the building blocks of workflow—think of them as a unit of work that needs to be executed. Activities are easy to create, either from writing code or by composing them from other activities. Out of the box, there are a set of activities that mostly provide structure, such as parallel execution, if/else, and calling a web service.
Workflow designer
This is the design surface in Visual Studio, which allows for the graphical composition of workflow, by placing activities within the workflow model.
Workflow runtime
Workflow runtime is a lightweight and extensible engine that executes the activities that make up a workflow. The runtime is hosted within any .NET process, enabling developers to bring workflow to anything, from a Windows forms application to an ASP.NET web site or a Windows service.
Rules engine
WF has a rules engine that enables declarative, rule-based development for workflows and any .NET application to use. Using the rule engine, you can eliminate hardcoded rules in your code and move them from the code to a more maintainable declarative format on the workflow diagram.
Although a workflow is mostly used in applications that have workflow-type business processes, you can use a workflow in almost any application as long as the application does complex operations. In this Start page application, some operations, like first visit, are complex and require multistep activities and decisions. So, such applications can benefit from workflow implementation.
Next: Building the Business Layer Using WF >>
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