Category Property

MessageQueue.Category Property


Gets or sets the queue category.

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

member Category : Guid with get, set

Property Value

Type: System.Guid

A Guid that represents the queue category (Message Queuing type identifier), which allows an application to categorize its queues. The default is Guid.empty.

Exception Condition

The queue category was set to an invalid value.


An error occurred when accessing a Message Queuing method.

The queue category allows an application to categorize its queues. For example, you can place all Billing queues in one category and all Order queues in another.

The Category property provides access to the Message Queuing Type ID property (which is read/write), accessible through the Queue Properties dialog box in the Computer Management Console. You can define a new category. Although you can use NewGuid to create a category value that is unique across all Guid values, such an action is unnecessary. The category value needs to be distinct only from other categories, not from all other Guid values. For example, you can assign {00000000-0000-0000-0000-000000000001} as the Category for one set of queues and {00000000-0000-0000-0000-000000000002} as the Category for another set.

It is not necessary to set the Category. The value can be null.

Setting this property modifies the Message Queuing queue. Therefore, any other MessageQueue instances are affected by the change.

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

Workgroup mode


Local computer


Local computer and direct format name


Remote computer


Remote computer and direct format name


The following code example gets and sets the value of a message queue's Category property.

// Set the queue's Category property value.
queue.Category =
    new System.Guid("00000000-0000-0000-0000-000000000001");

// Display the new value of the queue's Category property.
Console.WriteLine("MessageQueue.Category: {0}", queue.Category);

.NET Framework
Available since 1.1
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