MessageQueue.Exists Method

Determines whether a Message Queuing queue exists at the specified path.

Namespace: System.Messaging
Assembly: System.Messaging (in system.messaging.dll)

public static bool Exists (
	string path
)
public static boolean Exists (
	String path
)
public static function Exists (
	path : String
) : boolean

Parameters

path

The location of the queue to find.

Return Value

true if a queue with the specified path exists; otherwise, false.

Exception typeCondition

ArgumentException

The path syntax is not valid.

MessageQueueException

An error occurred when accessing a Message Queuing method.

-or-

The Exists method is being called on a remote private queue

InvalidOperationException

The application used format name syntax when verifying queue existence.

The Exists method determines whether a Message Queuing queue exists at a specified path. No method exists to determine whether a queue with a specified format name exists. For more information about the format name syntax and other path syntax forms, see the Path property.)

Exists is an expensive operation. Use it only when it is necessary within the application.

NoteNote

The Exists method does not support the FormatName prefix.

The syntax for the path parameter depends on the type of queue, as shown in the following table.

Queue type

Syntax

Public queue

MachineName\QueueName

Exists cannot be called to verify the existence of a remote private queue.

For more syntax, see the Path property.

Alternatively, you can use the Label to describe the queue path.

Reference

Syntax

Label

Label:[ label ]

The following table shows whether this method is available in various Workgroup modes.

Workgroup mode

Available

Local computer

Yes

Local computer and direct format name

No

Remote computer

No

Remote computer and direct format name

No

The following code example verifies whether a Message Queuing queue exists, and then deletes it.

using System;
using System.Messaging;

namespace MyProject
{
	/// <summary>
	/// Provides a container class for the example.
	/// </summary>
	public class MyNewQueue
	{

		//**************************************************
		// Provides an entry point into the application.
		//		 
		// This example verifies existence and attempts to 
		// delete a queue.
		//**************************************************

		public static void Main()
		{

			// Determine whether the queue exists.
			if (MessageQueue.Exists(".\\myQueue"))
			{
				try
				{
					// Delete the queue.
					MessageQueue.Delete(".\\myQueue");
				}
				catch(MessageQueueException e)
				{
					if(e.MessageQueueErrorCode == 
						MessageQueueErrorCode.AccessDenied)
					{
						Console.WriteLine("Access is denied. " + 
							"Queue might be a system queue.");
					}

					// Handle other sources of MessageQueueException.
				}

			}
		
			return;
		}

	}
}

package MyProject;

import System.*;
import System.Messaging.*;

/// <summary>
/// Provides a container class for the example.
/// </summary>
public class MyNewQueue
{
    //**************************************************
    // Provides an entry point into the application.
    //         
    // This example verifies existence and attempts to 
    // delete a queue.
    //**************************************************
    public static void main(String[] args)
    {
        // Determine whether the queue exists.
        if (MessageQueue.Exists(".\\myQueue")) {
            try {
                // Delete the queue.
                MessageQueue.Delete(".\\myQueue");
            }
            catch (MessageQueueException e) {
                if (e.get_MessageQueueErrorCode().
                    Equals(MessageQueueErrorCode.AccessDenied)) {
                    Console.WriteLine("Access is denied. "
                        + "Queue might be a system queue.");
                }
                // Handle other sources of MessageQueueException.
            }
        }        
        return;
    } //main
} //MyNewQueue 

  • Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see .

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0

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