WorkflowInvoker.Invoke Method ()

.NET Framework (current version)

Invokes a workflow synchronously using the workflow definition passed to the WorkflowInvoker constructor.

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

public IDictionary<string, object> Invoke()

Return Value

Type: System.Collections.Generic.IDictionary<String, Object>

A dictionary of the root activity’s OutArgument and InOutArgument values keyed by argument name that represent the outputs of the workflow.

This method blocks until the workflow has completed, including idle time. All workflow execution is guaranteed to execute on the invoking thread. To configure a time-out interval in which the workflow must complete, use one of the Invoke overloads that take a TimeSpan.

The following example invokes a workflow consisting of a single DiceRoll activity. The DiceRoll activity has two output arguments that represent the results of the dice roll operation. When the call to Invoke returns, each output argument is returned in the outputs dictionary, keyed by argument name. The workflow is invoked twice, using the workflow definition passed into to the WorkflowInvoker constructor.

public sealed class DiceRoll : CodeActivity
    public OutArgument<int> D1 { get; set; }
    public OutArgument<int> D2 { get; set; }

    static Random r = new Random();

    protected override void Execute(CodeActivityContext context)
        D1.Set(context, r.Next(1, 7));
        D2.Set(context, r.Next(1, 7));
WorkflowInvoker invoker = new WorkflowInvoker(new DiceRoll());

IDictionary<string, object> outputs =

Console.WriteLine("The two dice are {0} and {1}.",
    outputs["D1"], outputs["D2"]);

outputs = invoker.Invoke();

Console.WriteLine("The next two dice are {0} and {1}.",
    outputs["D1"], outputs["D2"]);

If the workflow's root activity has no output arguments or they are not needed by the host, they can be disregarded. The following example invokes a workflow consisting of a single WriteLine activity that does not have any output arguments.

Activity wf = new WriteLine
    Text = "Hello World."

WorkflowInvoker invoker = new WorkflowInvoker(wf);


.NET Framework
Available since 4.0
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