Introduction:
Windows Workflow Foundation is the programming model, engine and tools for quickly building workflow enabled applications on Windows. It consists of .NET classes, an in-process workflow engine, and designers for Visual Studio.
WF allows for two types of workflows. Sequential workflow is one that executes a series of steps in a defined sequence.
State machine workflow represents an ongoing project, in which a system continually transitions from one state to another. In this case, activities are not attached to a state.
Getting Started:
Workflow projects are created in the same way as other projects types in Visual Studio 2008. After starting Visual Studio 2008, you select File >>Project. In the Templates side, you select a Workflow type application.
In this example I am choosing Sequential Workflow Console Application template as you can see in Figure 1.
Figure 1.
This is the initial view of the visual workflow designer in Figure 2.
An activity represents a step in the workflow and is the fundamental building block of all WF workflows. All activity either directly or indirectly derive from the base class System.Workflow.ComponentModelActivity class.
Figure 2.
If you look at the Solutions Explorer, you will see something like this.
Figure 3.
Now, if you take a look at the Toolbox, you wull see a list of the standard activities available in Visual Studio 2008.
Figure 4.
Just drag and drop Code activity onto the workflow. The Code activity is a simple way to execute any code that you want as a step in the workflow.
Figure 5.
Figure6.
private void codeActivity1_ExecuteCode(object sender, EventArgs e)
{
Console.WriteLine("Hello Raj Beniwal!! Welcome to WF!");
}
Figure 7.
When workflow has been implemented it adds new file Program.cs, which has following code.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Workflow.Runtime;
using System.Workflow.Runtime.Hosting;
namespace GettingStartedWF
{
class Program
{
static void Main(string[] args)
{
using(WorkflowRuntime workflowRuntime = new WorkflowRuntime())
{
AutoResetEvent waitHandle = new AutoResetEvent(false);
workflowRuntime.WorkflowCompleted += delegate(object sender, WorkflowCompletedEventArgs e) {waitHandle.Set();};
workflowRuntime.WorkflowTerminated += delegate(object sender, WorkflowTerminatedEventArgs e)
{
Console.WriteLine(e.Exception.Message);
waitHandle.Set();
};
WorkflowInstance instance = workflowRuntime.CreateWorkflow(typeof(GettingStartedWF.Workflow1));
instance.Start();
waitHandle.WaitOne();
}
}
}
}
Now I am showing how to pass parameters in workflow. In WF parameters will be passed directly from the host console application.
private void codeActivity1_ExecuteCode(object sender, EventArgs e)
{
Console.WriteLine("Hello {0}, {1}", Name, Message);
}
public string Name
{
get;
set;
}
public string Message
{
get;
set;
}
static void Main(string[] args)
{
using(WorkflowRuntime workflowRuntime = new WorkflowRuntime())
{
AutoResetEvent waitHandle = new AutoResetEvent(false);
workflowRuntime.WorkflowCompleted += delegate(object sender, WorkflowCompletedEventArgs e) {waitHandle.Set();};
workflowRuntime.WorkflowTerminated += delegate(object sender, WorkflowTerminatedEventArgs e)
{
Console.WriteLine(e.Exception.Message);
waitHandle.Set();
};
Dictionary<string, object> wfArguments = new Dictionary<string, object>();
wfArguments.Add("Name", "RAJ!");
wfArguments.Add("Message", "How you doing???");
WorkflowInstance instance = workflowRuntime.CreateWorkflow(typeof(GettingStartedWF.Workflow1), wfArguments);
instance.Start();
waitHandle.WaitOne();
Console.WriteLine("Press any key to exit");
Console.ReadKey();
}
}
For more information see attached application.
Figure 8.
Summary
In this example you saw how to get started with WF step by step.