- Create a new Console Application project. This application will invoke a workflow
- Add a new Sequential Workflow Library project to the solution. This is where all the workflows will be kept
This step will create a new project within current solution with one sequential workflow without code separation. - Right click on Workflow1.cs in Solution Explorer and choose View Designer.
You should see an empty sequential workflow definition
- Drag one Code activity from toolbox onto the workflow definition
- Open the Properties tab and:
- change (Name) to printMessage
- change ExecuteCode to PrintMessageCode
- You can see that the PrintMessageCode method has been added automatically.
Add the method implementation:
private void PrintMessageCode(object sender, EventArgs e)
{
Console.WriteLine("Simple Sequential Workflow Invocation");
Console.WriteLine(String.Format("Date: {0}", DateTime.Now));
Console.WriteLine(String.Format("Workflow Instance ID: {0}", WorkflowInstanceId));
}
- Add a new Class library project to the solution. It will implement workflow hosting routines for the application
- Rename Class1.cs to Hosting.cs (along with class names and references)
- In the WorkflowInvoker project add a reference to all System.Workflow.* assemblies:
and then to the WorkflowLibrary project:
- Replace the content of Hosting.cs with code below:
using System;
using System.Workflow.Runtime;
namespace WorkflowInvoker
{
internal static class Hosting
{
private static WorkflowRuntime runtime;
public static WorkflowRuntime Runtime
{
get { return runtime; }
}
static Hosting()
{
StartRuntime();
}
private static void StartRuntime()
{
AppDomain.CurrentDomain.ProcessExit += StopRuntime;
AppDomain.CurrentDomain.DomainUnload += StopRuntime;
runtime = new WorkflowRuntime();
runtime.StartRuntime();
}
private static void StopRuntime(object sender, EventArgs e)
{
if (!runtime.IsStarted)
return;
try
{
runtime.StopRuntime();
}
catch (ObjectDisposedException) {}
}
public static Guid InvokeWorkflow(Type workflowType)
{
WorkflowInstance instance = runtime.CreateWorkflow(workflowType);
instance.Start();
return instance.InstanceId;
}
}
}
- Add a class named Invoker to the WorkflowInvoker project:
using System;
using System.Workflow.Runtime;
using System.Threading;
using WorkflowLibrary;
namespace WorkflowInvoker
{
public static class Invoker
{
private static readonly AutoResetEvent waitHandle;
public static AutoResetEvent WaitHandle
{
get { return waitHandle; }
}
static Invoker()
{
waitHandle = new AutoResetEvent(false);
WorkflowRuntime runtime = Hosting.Runtime;
runtime.WorkflowCompleted += WorkflowCompleted;
runtime.WorkflowTerminated += WorkflowTerminated;
runtime.WorkflowIdled += WorkflowIdled;
}
private static void WorkflowIdled(object sender, WorkflowEventArgs e)
{
Console.WriteLine("Workflow Runtime Event: Workflow instance idled");
}
private static void WorkflowTerminated(object sender, WorkflowTerminatedEventArgs e)
{
Console.WriteLine(
String.Format(
"Workflow Runtime Event: Workflow instance terminated. " +
"Reason: '{0}'", e.Exception.Message));
waitHandle.Set();
}
private static void WorkflowCompleted(object sender, WorkflowCompletedEventArgs e)
{
Console.WriteLine("Workflow Runtime Event: Workflow instance completed");
waitHandle.Set();
}
public static Guid RunSimpleWorkflow()
{
return Hosting.InvokeWorkflow(typeof (Workflow1));
}
}
}
- In the WorkflowApplication project add a reference to the WorkflowInvoker library:
- Write the code in the Main method
static void Main(string[] args)
{
Invoker.RunSimpleWorkflow();
Invoker.WaitHandle.WaitOne();
Console.ReadLine();
}
- Run the application:
- Warning: by default, all workflow instances are being run in separate threads, detached from the main thread of execution. Thus we needed to suspend execution of the main thread using synchronization mechanisms i.e. AutoResetEvent. You should also be aware of traps and issues that might emerge when dealing with multithreading tasks and problems.
- Right click on Workflow1.cs in Solution Explorer and choose View Designer.
- Add a Delay activity and a second Code activity below the printMessage activity.
- Go to Properties tab and:
- Change the (Name) property of the added Code activity to afterDelay
- Change the ExecuteCode property of afterDelay to AfterDelayCode, go back to the designer
- Change the (Name) property of the Delay activity to delay
- Change the InitializeTimeoutDuration property of delay to DelayInit, go back to the designer
- Double click the yellow "Bind property" icon near TimeoutDuration caption:
- Go to the "Bind to a new member" tab and:
- set "New member name to DelayTimeoutDuration
- select "Create Property"
this will create a new Dependency Property called DelayTimeoutDuration
- Fill the DelayInit and AfterDelayCode methods:
private void AfterDelayCode(object sender, EventArgs e)
{
Console.WriteLine("Timer expired");
}
private void DelayInit(object sender, EventArgs e)
{
Console.WriteLine("Delay activity initialized");
Console.WriteLine(String.Format("Delay duration: {0}", DelayTimeoutDuration));
}
- Change the InvokeWorkflow method in Hosting.cs:
public static Guid InvokeWorkflow(Type workflowType, Dictionary<string, object> parameters)
{
WorkflowInstance instance = runtime.CreateWorkflow(workflowType, parameters);
instance.Start();
return instance.InstanceId;
}
- Change the RunSimpleWorkflow method in Invoke.cs:
Notice: the parameters' names are represented by and mapped to the workflow properties' names respectively
public static Guid RunSimpleWorkflow(TimeSpan delayDuration)
{
Dictionary<string, object> parameters = new Dictionary<string, object> {{"DelayTimeoutDuration", delayDuration}};
return Hosting.InvokeWorkflow(typeof (Workflow1), parameters);
}
- Replace the content of Program.cs with code below:
using System;
using WorkflowInvoker;
namespace WorkflowApplication
{
class Program
{
static void Main(string[] args)
{
Invoker.RunSimpleWorkflow(new TimeSpan(0, 0, 5)); // 5 seconds
Invoker.WaitHandle.WaitOne();
Console.ReadLine();
}
}
}
- Run the application:
Note that when workflow reaches the delay activity, it enters the idle state.