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WorkflowInvoker.CancelAsync Method

Attempts to cancel the workflow that was invoked with the specified userState.

Namespace:  System.Activities
Assembly:  System.Activities (in System.Activities.dll)

member CancelAsync : 
        userState:Object -> unit 

Parameters

userState
Type: System.Object
The token for the workflow to cancel.

Only a workflow invoked by one of the InvokeAsync() overloads that takes a userState parameter can be canceled.

If the cancellation succeeds, the Cancelled() property of the InvokeCompletedEventArgs passed to the InvokeCompleted handler is set to true; otherwise, it is set to false.

The following example invokes a workflow consisting of a LongRunningDiceRoll activity. The LongRunningDiceRoll activity has two output arguments that represent the results of the dice roll operation. Once the workflow is invoked, the host attempts to cancel the workflow.


public sealed class LongRunningDiceRoll : Activity
{
    public OutArgument<int> D1 { get; set; }
    public OutArgument<int> D2 { get; set; }

    public LongRunningDiceRoll()
    {
        this.Implementation = () => new Sequence
        {
            Activities =
            {
                new WriteLine
                {
                    Text = "Rolling the dice for 5 seconds."
                },
                new Delay
                {
                    Duration = TimeSpan.FromSeconds(5)
                },
                new DiceRoll
                {
                    D1 = new OutArgument<int>(env => this.D1.Get(env)),
                    D2 = new OutArgument<int>(env => this.D2.Get(env))
                }
            }
        };
    }
}



AutoResetEvent syncEvent = new AutoResetEvent(false);

WorkflowInvoker invoker = new WorkflowInvoker(new LongRunningDiceRoll());

invoker.InvokeCompleted += delegate(object sender, InvokeCompletedEventArgs args)
{
    if (args.Cancelled == true)
    {
        Console.WriteLine("The workflow was cancelled.");
    }
    else if (args.Error != null)
    {
        Console.WriteLine("Exception: {0}\n{1}",
            args.Error.GetType().FullName,
            args.Error.Message);
    }
    else
    {
        Console.WriteLine("The two dice are {0} and {1}.",
            args.Outputs["D1"], args.Outputs["D2"]);
    }

    syncEvent.Set();
};

string userState = "CancelAsync Example";
invoker.InvokeAsync(userState);

Console.WriteLine("Waiting for the workflow to complete.");
Thread.Sleep(TimeSpan.FromSeconds(1));

Console.WriteLine("Attempting to cancel the workflow.");
invoker.CancelAsync(userState);

// Wait for the workflow to complete.
syncEvent.WaitOne();

Console.WriteLine("The workflow is either completed or cancelled.");


.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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