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WorkflowQueuingService.Exists Method

Tests for the existence of the specified WorkflowQueue.

Namespace:  System.Workflow.Runtime
Assembly:  System.Workflow.Runtime (in System.Workflow.Runtime.dll)

public bool Exists(
	IComparable queueName
)

Parameters

queueName
Type: System.IComparable

The name of the WorkflowQueue.

Return Value

Type: System.Boolean
true if the WorkflowQueue exists; otherwise, false.

ExceptionCondition
ArgumentNullException

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

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);
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0
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