MessageQueue.GetMessageQueueEnumerator Method

Definition

Namespace:

System.Messaging

Assembly:

System.Messaging.dll

Creates an enumerator object for a dynamic listing of the public queues on the network.

Overloads

GetMessageQueueEnumerator()	Provides forward-only cursor semantics to enumerate through all public queues on the network.
GetMessageQueueEnumerator(MessageQueueCriteria)	Provides forward-only cursor semantics to enumerate through all public queues on the network that meet the specified criteria.

GetMessageQueueEnumerator()

Provides forward-only cursor semantics to enumerate through all public queues on the network.

public:
 static System::Messaging::MessageQueueEnumerator ^ GetMessageQueueEnumerator();

public static System.Messaging.MessageQueueEnumerator GetMessageQueueEnumerator ();

static member GetMessageQueueEnumerator : unit -> System.Messaging.MessageQueueEnumerator

Public Shared Function GetMessageQueueEnumerator () As MessageQueueEnumerator

Returns

MessageQueueEnumerator

A MessageQueueEnumerator that provides a dynamic listing of all the public message queues on the network.

Examples

The following code example iterates through all the message queues in the network, and examines the path for each queue. Finally, it displays the number of public queues on the network.

#using <System.dll>
#using <System.Messaging.dll>

using namespace System;
using namespace System::Messaging;

//**************************************************
// Iterates through message queues and examines the
// path for each queue. Also displays the number of
// public queues on the network.
//**************************************************
void ListPublicQueues()
{
   
   // Holds the count of private queues.
   int numberQueues = 0;
   
   // Get a cursor into the queues on the network.
   MessageQueueEnumerator^ myQueueEnumerator = MessageQueue::GetMessageQueueEnumerator();
   
   // Move to the next queue and read its path.
   while ( myQueueEnumerator->MoveNext() )
   {
      
      // Increase the count if priority is Lowest.
      Console::WriteLine( myQueueEnumerator->Current->Path );
      numberQueues++;
   }

   
   // Display final count.
   Console::WriteLine( "Number of public queues: {0}", numberQueues );
   return;
}


//**************************************************
// Provides an entry point into the application.
//   
// This example uses a cursor to step through the
// message queues and list the public queues on the
// network.
//**************************************************
int main()
{
   
   // Output the count of Lowest priority messages.
   ListPublicQueues();
}

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 uses a cursor to step through the
        // message queues and list the public queues on the
        // network.
        //**************************************************

        public static void Main()
        {
            // Create a new instance of the class.
            MyNewQueue myNewQueue = new MyNewQueue();

            // Output the count of Lowest priority messages.
            myNewQueue.ListPublicQueues();
                        
            return;
        }

        //**************************************************
        // Iterates through message queues and examines the
        // path for each queue. Also displays the number of
        // public queues on the network.
        //**************************************************
        
        public void ListPublicQueues()
        {
            // Holds the count of private queues.
            uint numberQueues = 0;
    
            // Get a cursor into the queues on the network.
            MessageQueueEnumerator myQueueEnumerator =
                MessageQueue.GetMessageQueueEnumerator();

            // Move to the next queue and read its path.
            while(myQueueEnumerator.MoveNext())
            {
                // Increase the count if priority is Lowest.
                Console.WriteLine(myQueueEnumerator.Current.Path);
                numberQueues++;
            }

            // Display final count.
            Console.WriteLine("Number of public queues: " +
                numberQueues.ToString());
            
            return;
        }
    }
}

Imports System.Messaging



Public Class MyNewQueue


        
        ' Provides an entry point into the application.
        '		 
        ' This example uses a cursor to step through the
        ' message queues and list the public queues on the
        ' network.
        

        Public Shared Sub Main()

            ' Create a new instance of the class.
            Dim myNewQueue As New MyNewQueue()

            ' Output the count of Lowest priority messages.
            myNewQueue.ListPublicQueues()

            Return

        End Sub


        
        ' Iterates through message queues and examines the
        ' path for each queue. Also displays the number of
        ' public queues on the network.
        

        Public Sub ListPublicQueues()

            ' Holds the count of private queues.
            Dim numberQueues As Int32 = 0

            ' Get a cursor into the queues on the network.
            Dim myQueueEnumerator As MessageQueueEnumerator = _
                MessageQueue.GetMessageQueueEnumerator()

            ' Move to the next queue and read its path.
            While myQueueEnumerator.MoveNext()
                ' Increase the count if the priority is Lowest.
                Console.WriteLine(myQueueEnumerator.Current.Path)
                numberQueues += 1
            End While

            ' Display final count.
            Console.WriteLine(("Number of public queues: " + _
                numberQueues.ToString()))

            Return

        End Sub

End Class

Remarks

This overload of GetMessageQueueEnumerator returns an enumeration of all the public queues that are on the network.

Because the cursor is associated with a dynamic listing, the enumeration reflects any modification you make to a queue list for queues deleted or added beyond the cursor's current position. Additions or deletion of queues located before the cursor's current position are not reflected. For example, the enumerator can automatically access a queue appended beyond the cursor position but not one inserted before that position. However, you can reset the enumeration, thereby moving the cursor back to the beginning of the list, by calling Reset for the MessageQueueEnumerator.

There is no defined ordering of queues in a network. An enumerator does not order them, for example, by computer, label, public or private status, or any other accessible criteria.

If you want a static snapshot of the queues on the network rather than a dynamic connection to them, call GetPublicQueues or GetPrivateQueuesByMachine(String). Each of these two methods returns an array of MessageQueue objects, which represent the queues at the time the method was called.

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

See also

• GetPublicQueues()
• GetMessageEnumerator2()

GetMessageQueueEnumerator(MessageQueueCriteria)

Provides forward-only cursor semantics to enumerate through all public queues on the network that meet the specified criteria.

public:
 static System::Messaging::MessageQueueEnumerator ^ GetMessageQueueEnumerator(System::Messaging::MessageQueueCriteria ^ criteria);

public static System.Messaging.MessageQueueEnumerator GetMessageQueueEnumerator (System.Messaging.MessageQueueCriteria criteria);

static member GetMessageQueueEnumerator : System.Messaging.MessageQueueCriteria -> System.Messaging.MessageQueueEnumerator

Public Shared Function GetMessageQueueEnumerator (criteria As MessageQueueCriteria) As MessageQueueEnumerator

Parameters

criteria

MessageQueueCriteria

A MessageQueueCriteria that contains the criteria used to filter the available message queues.

Returns

MessageQueueEnumerator

A MessageQueueEnumerator that provides a dynamic listing of the public message queues on the network that satisfy the restrictions specified by the criteria parameter.

Examples

The following code example iterates through message queues and displays the path of each queue that was created in the last day and that exists on the computer "MyComputer".

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

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

   // Iterates through message queues and displays the
   // path of each queue that was created in the last
   // day and that exists on the computer "MyComputer". 
   void ListPublicQueuesByCriteria()
   {
      UInt32 numberQueues = 0;
      
      // Specify the criteria to filter by.
      MessageQueueCriteria^ myCriteria = gcnew MessageQueueCriteria;
      myCriteria->MachineName = "MyComputer";
      myCriteria->CreatedAfter = DateTime::Now.Subtract( TimeSpan(1,0,0,0) );
      
      // Get a cursor into the queues on the network.
      MessageQueueEnumerator^ myQueueEnumerator = MessageQueue::GetMessageQueueEnumerator( myCriteria );
      
      // Move to the next queue and read its path.
      while ( myQueueEnumerator->MoveNext() )
      {
         
         // Increase the count if priority is Lowest.
         Console::WriteLine( myQueueEnumerator->Current->Path );
         numberQueues++;
      }

      
      // Handle no queues matching the criteria.
      if ( numberQueues == 0 )
      {
         Console::WriteLine( "No public queues match criteria." );
      }

      return;
   }

};

int main()
{
   
   // Create a new instance of the class.
   MyNewQueue^ myNewQueue = gcnew MyNewQueue;
   
   // Output the count of Lowest priority messages.
   myNewQueue->ListPublicQueuesByCriteria();
   return 0;
}

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 uses a cursor to step through the
        // message queues and list the public queues on the
        // network that specify certain criteria.
        //**************************************************

        public static void Main()
        {
            // Create a new instance of the class.
            MyNewQueue myNewQueue = new MyNewQueue();

            // Output the count of Lowest priority messages.
            myNewQueue.ListPublicQueuesByCriteria();
                        
            return;
        }

        //**************************************************
        // Iterates through message queues and displays the
        // path of each queue that was created in the last
        // day and that exists on the computer "MyComputer".
        //**************************************************
        
        public void ListPublicQueuesByCriteria()
        {
            uint numberQueues = 0;
            
            // Specify the criteria to filter by.
            MessageQueueCriteria myCriteria = new
                MessageQueueCriteria();
            myCriteria.MachineName = "MyComputer";
            myCriteria.CreatedAfter = DateTime.Now.Subtract(new
                TimeSpan(1,0,0,0));

            // Get a cursor into the queues on the network.
            MessageQueueEnumerator myQueueEnumerator =
                MessageQueue.GetMessageQueueEnumerator(myCriteria);

            // Move to the next queue and read its path.
            while(myQueueEnumerator.MoveNext())
            {
                // Increase the count if priority is Lowest.
                Console.WriteLine(myQueueEnumerator.Current.Path);
                numberQueues++;
            }

            // Handle no queues matching the criteria.
            if (numberQueues == 0)
            {
                Console.WriteLine("No public queues match criteria.");
            }

            return;
        }
    }
}

Imports System.Messaging

 
Public Class MyNewQueue


        '
        ' Provides an entry point into the application.
        '		 
        ' This example uses a cursor to step through the
        ' message queues and list the public queues on the
        ' network that specify certain criteria.
        

        Public Shared Sub Main()

            ' Create a new instance of the class.
            Dim myNewQueue As New MyNewQueue()

            ' Output the count of Lowest priority messages.
            myNewQueue.ListPublicQueuesByCriteria()

            Return

        End Sub


        
        ' Iterates through message queues and displays the
        ' path of each queue that was created in the last
        ' day and that exists on the computer "MyComputer". 
        

        Public Sub ListPublicQueuesByCriteria()

            Dim numberQueues As Int32 = 0

            ' Specify the criteria to filter by.
            Dim myCriteria As New MessageQueueCriteria()
            myCriteria.MachineName = "MyComputer"
            myCriteria.CreatedAfter = DateTime.Now.Subtract(New _
                TimeSpan(1, 0, 0, 0))


            ' Get a cursor into the queues on the network.
            Dim myQueueEnumerator As MessageQueueEnumerator = _
                MessageQueue.GetMessageQueueEnumerator(myCriteria)

            ' Move to the next queue and read its path.
            While myQueueEnumerator.MoveNext()
                ' Increase the count if the priority is Lowest.
                Console.WriteLine(myQueueEnumerator.Current.Path)
                numberQueues += 1
            End While

            ' Handle no queues matching the criteria.
            If numberQueues = 0 Then
                Console.WriteLine("No queues match the criteria.")
            End If

            Return

        End Sub

End Class

Remarks

This overload of GetMessageQueueEnumerator returns a listing of all the public queues on the network that satisfy criteria defined in the application criteria. You can specify the criteria to include, for example, queue creation or modification time, computer name, label, category, or any combination of these.

Because the cursor is associated with a dynamic listing, the enumeration reflects any modification you make to a queue that occurs beyond the cursor's current position. Changes to queues located before the cursor's current position are not reflected. For example, the enumerator can automatically access a queue appended beyond the cursor position but not one inserted before that position. However, you can reset the enumeration, thereby moving the cursor back to the beginning of the list, by calling Reset for the MessageQueueEnumerator.

There is no defined ordering of queues in a network. An enumerator does not order them, for example, by computer, label, public or private status, or any other accessible criteria.

If you want a static snapshot of the queues on the network rather than a dynamic connection to them, specify criteria for GetPublicQueues or call GetPrivateQueuesByMachine(String). Each of these two methods returns an array of MessageQueue objects, which represent the queues at the time the method was called. Calling GetPublicQueuesByCategory(Guid), GetPublicQueuesByLabel(String), or GetPublicQueuesByMachine(String) provides the same results as calling GetPublicQueues with the filtering criteria of Category, Label, and MachineName, respectively.

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

See also

• GetPublicQueues()
• GetMessageEnumerator2()