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MessageQueue::GetPublicQueuesByCategory Method

Retrieves all the public queues on the network that belong to the specified category.

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

public:
static array<MessageQueue^>^ GetPublicQueuesByCategory(
	Guid category
)

Parameters

category
Type: System::Guid

A Guid that groups the set of queues to be retrieved.

Return Value

Type: array<System.Messaging::MessageQueue>
An array of MessageQueue objects that reference the retrieved public queues.

ExceptionCondition
MessageQueueException

An error occurred when accessing a Message Queuing method.

Use this method to filter the public queues by category. The Category property provides access to the Message Queuing type ID property (which is read/write) of a particular queue. Although you can use NewGuid to create a category value that is unique across all Guid values, it is not necessary. 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.

GetPublicQueuesByCategory(Guid) retrieves a static snapshot of the queues. To interact with a dynamic list of the queues, use GetMessageQueueEnumerator. You can specify the category as part of the MessageQueueCriteria you pass into the method.

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

Workgroup mode

Available

Local computer

No

Local computer and direct format name

No

Remote computer

No

Remote computer and direct format name

No

The following code example retrieves lists of queues.

#using <system.dll>
#using <system.messaging.dll>

using namespace System;
using namespace System::Messaging;
using namespace System::Collections;
ref class MyNewQueue
{
public:

   // Gets a list of queues with a specified category. 
   // Sends a broadcast message to all queues in that 
   // category. 
   void GetQueuesByCategory()
   {

      // Get a list of queues with the specified category. 
      array<MessageQueue^>^QueueList = MessageQueue::GetPublicQueuesByCategory( Guid(" {00000000-0000-0000-0000-000000000001}") );

      // Send a broadcast message to each queue in the array.
      IEnumerator^ myEnum = QueueList->GetEnumerator();
      while ( myEnum->MoveNext() )
      {
         MessageQueue^ queueItem = safe_cast<MessageQueue^>(myEnum->Current);
         queueItem->Send( "Broadcast message." );
      }

      return;
   }


   // Gets a list of queues with a specified label. 
   // Sends a broadcast message to all queues with that 
   // label. 
   void GetQueuesByLabel()
   {

      // Get a list of queues with the specified label. 
      array<MessageQueue^>^QueueList = MessageQueue::GetPublicQueuesByLabel( "My Label" );

      // Send a broadcast message to each queue in the array.
      IEnumerator^ myEnum = QueueList->GetEnumerator();
      while ( myEnum->MoveNext() )
      {
         MessageQueue^ queueItem = safe_cast<MessageQueue^>(myEnum->Current);
         queueItem->Send( "Broadcast message." );
      }

      return;
   }


   // Gets a list of queues on a specified computer.  
   // Displays the list on screen. 
   void GetQueuesByComputer()
   {

      // Get a list of queues on the specified computer. 
      array<MessageQueue^>^QueueList = MessageQueue::GetPublicQueuesByMachine( "MyComputer" );

      // Display the paths of the queues in the list.
      IEnumerator^ myEnum = QueueList->GetEnumerator();
      while ( myEnum->MoveNext() )
      {
         MessageQueue^ queueItem = safe_cast<MessageQueue^>(myEnum->Current);
         Console::WriteLine( queueItem->Path );
      }

      return;
   }


   // Gets a list of all public queues. 
   void GetAllPublicQueues()
   {

      // Get a list of public queues. 
      array<MessageQueue^>^QueueList = MessageQueue::GetPublicQueues();
      return;
   }


   // Gets a list of all public queues that match  
   // specified criteria. Displays the list on  
   // screen. 
   void GetPublicQueuesByCriteria()
   {

      // Define criteria to filter the queues.
      MessageQueueCriteria^ myCriteria = gcnew MessageQueueCriteria;
      myCriteria->CreatedAfter = DateTime::Now.Subtract( TimeSpan(1,0,0,0) );
      myCriteria->ModifiedBefore = DateTime::Now;
      myCriteria->MachineName = ".";
      myCriteria->Label = "My Queue";

      // Get a list of queues with that criteria. 
      array<MessageQueue^>^QueueList = MessageQueue::GetPublicQueues( myCriteria );

      // Display the paths of the queues in the list.
      IEnumerator^ myEnum = QueueList->GetEnumerator();
      while ( myEnum->MoveNext() )
      {
         MessageQueue^ queueItem = safe_cast<MessageQueue^>(myEnum->Current);
         Console::WriteLine( queueItem->Path );
      }

      return;
   }


   // Gets a list of private queues on the local  
   // computer. Displays the list on screen. 
   void GetPrivateQueues()
   {

      // Get a list of queues with the specified category. 
      array<MessageQueue^>^QueueList = MessageQueue::GetPrivateQueuesByMachine( "." );

      // Display the paths of the queues in the list.
      IEnumerator^ myEnum = QueueList->GetEnumerator();
      while ( myEnum->MoveNext() )
      {
         MessageQueue^ queueItem = safe_cast<MessageQueue^>(myEnum->Current);
         Console::WriteLine( queueItem->Path );
      }

      return;
   }

};


// Provides an entry point into the application. 
// This example gets lists of queues by a variety 
// of criteria. 
int main()
{

   // Create a new instance of the class.
   MyNewQueue^ myNewQueue = gcnew MyNewQueue;

   // Send normal and high priority messages.
   myNewQueue->GetQueuesByCategory();
   myNewQueue->GetQueuesByLabel();
   myNewQueue->GetQueuesByComputer();
   myNewQueue->GetAllPublicQueues();
   myNewQueue->GetPublicQueuesByCriteria();
   myNewQueue->GetPrivateQueues();
   return 0;
}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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