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WorkflowQueuingService.Exists(IComparable) Method

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Definition

Namespace:
System.Workflow.Runtime
Assembly:
System.Workflow.Runtime.dll

Tests for the existence of the specified WorkflowQueue.

public:
 bool Exists(IComparable ^ queueName);
public bool Exists (IComparable queueName);
member this.Exists : IComparable -> bool
Public Function Exists (queueName As IComparable) As Boolean

Parameters

queueName
IComparable

The name of the WorkflowQueue.

Returns

Boolean

true if the WorkflowQueue exists; otherwise, false.

Exceptions

ArgumentNullException

queueName is a null reference (Nothing in Visual Basic).

Examples

The following code example demonstrates a method, named CreateQueue, that initializes a WorkflowQueuingService object by calling the ActivityExecutionContext.GetService method. The code then uses the Exists method to determine if a WorkflowQueue with a specified name exists. If it does not exist, the code calls the CreateWorkflowQueue method; if it does the code calls the GetWorkflowQueue method.

This code example is part of the File Watcher Activity SDK Sample from the FileSystemEvent.cs file. For more information, see File System Watcher Activity.

private WorkflowQueue CreateQueue(ActivityExecutionContext context)
{
    Console.WriteLine("CreateQueue");
    WorkflowQueuingService qService = context.GetService<WorkflowQueuingService>();

    if (!qService.Exists(this.QueueName))
    {
        qService.CreateWorkflowQueue(this.QueueName, true);
    }

    return qService.GetWorkflowQueue(this.QueueName);
}

Private Function CreateQueue(ByVal context As ActivityExecutionContext) As WorkflowQueue
    Console.WriteLine("CreateQueue")
    Dim qService As WorkflowQueuingService = context.GetService(Of WorkflowQueuingService)()

    If Not qService.Exists(Me.queueName) Then
        qService.CreateWorkflowQueue(Me.queueName, True)
    End If

    Return qService.GetWorkflowQueue(Me.QueueName)
End Function

Applies to

See also