Windows Workflow Foundation (WF)
Windows Workflow Foundation (WF) is a Microsoft technology that allows developers to create and manage dynamic workflows and business processes within applications. It provides a programming model, a runtime engine, and tools for designing, executing, and managing workflows.
Key Concepts
- Activities: The basic building blocks of a workflow. Each activity represents a discrete unit of work. WF provides a rich set of built-in activities (e.g.,
Sequence,If,While,WriteLine) and allows for the creation of custom activities. - Workflow Definition: The XML representation of a workflow, defining the sequence and logic of activities. This definition can be created visually using the WF Designer or programmatically.
- Workflow Runtime: The engine that executes workflow instances. It manages the state, scheduling, and persistence of workflows.
- Persistence: The ability to save the state of a workflow instance to a durable store (like a database) so it can be resumed later, even after the application has been closed or restarted.
- Tracking: The mechanism for monitoring the execution of a workflow, providing audit trails and diagnostic information.
Getting Started
To start developing with Windows Workflow Foundation, you will typically use Visual Studio. The .NET Framework 3.5 SDK includes the necessary libraries and tools.
Here's a simple example of a sequential workflow that prints a message:
using System;
using System.Collections.Generic;
using System.Workflow.Activities;
using System.Workflow.ComponentModel;
// Define a simple custom activity
public class GreetActivity : Activity
{
public InArgument Name { get; set; }
protected override ActivityExecutionStatus Execute(ActivityExecutionContext executionContext)
{
Console.WriteLine($"Hello, {Name.Get(executionContext)}!");
return ActivityExecutionStatus.Closed;
}
}
// Define the main workflow
public class MyWorkflow : SequentialWorkflowActivity
{
public MyWorkflow()
{
Activities.Add(new GreetActivity { Name = new InArgument("World") });
Activities.Add(new WriteLine { Text = "Workflow completed." });
}
}
// Example of how to run the workflow
public class Program
{
public static void Main(string[] args)
{
MyWorkflow workflow = new MyWorkflow();
workflow.Run();
}
}
Benefits of WF
- Increased Productivity: Visual design tools and a rich set of built-in activities accelerate development.
- Improved Maintainability: Separation of business logic from application code makes workflows easier to update and manage.
- Enhanced Flexibility: Support for dynamic updates and complex business processes.
- Interoperability: WF can be integrated with other .NET technologies like WCF and ASP.NET.
Note: While WF was a powerful technology in .NET Framework 3.5, for new development in .NET Core and .NET 5+, consider using Durable Functions or other modern orchestration solutions.