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PeekCompletedEventHandler Delegate

Represents the method that will handle the PeekCompleted event of a MessageQueue.

[Visual Basic]
<Serializable>
Public Delegate Sub PeekCompletedEventHandler( _
   ByVal sender As Object, _
   ByVal e As PeekCompletedEventArgs _
)
[C#]
[Serializable]
public delegate void PeekCompletedEventHandler(
   object sender,
   PeekCompletedEventArgs e
);
[C++]
[Serializable]
public __gc __delegate void PeekCompletedEventHandler(
   Object* sender,
   PeekCompletedEventArgs* e
);

[JScript] In JScript, you can use the delegates in the .NET Framework, but you cannot define your own.

Parameters [Visual Basic, C#, C++]

The declaration of your event handler must have the same parameters as the PeekCompletedEventHandler delegate declaration.

sender
The source of the event, the MessageQueue.
e
A PeekCompletedEventArgs that contains the event data.

Remarks

When you create a PeekCompletedEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.

Example

[Visual Basic, C#, C++] The following example illustrates how to create an event delegate (PeekCompletedEventHandler) for the event handler (MyPeekCompleted) and associate it with the MessageQueue.PeekCompleted event. The event handler peeks a message and writes its label to the screen.

[Visual Basic] 
Imports System
Imports 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 performs asynchronous peek operation
        ' processing.
        '**************************************************

        Public Shared Sub Main()
            ' Create an instance of MessageQueue. Set its formatter.
            Dim myQueue As New MessageQueue(".\myQueue")
            myQueue.Formatter = New XmlMessageFormatter(New Type() _
                {GetType([String])})

            ' Add an event handler for the PeekCompleted event.
            AddHandler myQueue.PeekCompleted, AddressOf _
                MyPeekCompleted

            ' Begin the asynchronous peek operation.
            myQueue.BeginPeek()

            ' Do other work on the current thread.
            Return
        End Sub 'Main


        '**************************************************
        ' Provides an event handler for the PeekCompleted
        ' event.
        '**************************************************

        Private Shared Sub MyPeekCompleted(ByVal [source] As _
            [Object], ByVal asyncResult As PeekCompletedEventArgs)

            ' Connect to the queue.
            Dim mq As MessageQueue = CType([source], MessageQueue)

            ' End the asynchronous peek operation.
            Dim m As Message = mq.EndPeek(asyncResult.AsyncResult)

            ' Display message information on the screen.
            Console.WriteLine(("Message: " + CStr(m.Body)))

            ' Restart the asynchronous peek operation.
            mq.BeginPeek()

            Return

        End Sub 'MyPeekCompleted

    End Class 'MyNewQueue
End Namespace 'MyProject

[C#] 
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 performs asynchronous peek operation
        // processing.
        //**************************************************

        public static void Main()
        {
            // Create an instance of MessageQueue. Set its formatter.
            MessageQueue myQueue = new MessageQueue(".\\myQueue");
            myQueue.Formatter = new XmlMessageFormatter(new Type[]
                {typeof(String)});

            // Add an event handler for the PeekCompleted event.
            myQueue.PeekCompleted += new 
                PeekCompletedEventHandler(MyPeekCompleted);
            
            // Begin the asynchronous peek operation.
            myQueue.BeginPeek();
            
            // Do other work on the current thread.

            return;
        }


        //**************************************************
        // Provides an event handler for the PeekCompleted
        // event.
        //**************************************************
        
        private static void MyPeekCompleted(Object source, 
            PeekCompletedEventArgs asyncResult)
        {
            // Connect to the queue.
            MessageQueue mq = (MessageQueue)source;

            // End the asynchronous peek operation.
            Message m = mq.EndPeek(asyncResult.AsyncResult);

            // Display message information on the screen.
            Console.WriteLine("Message: " + (string)m.Body);

            // Restart the asynchronous peek operation.
            mq.BeginPeek();
            
            return; 
        }
    }
}

[C++] 
#using <mscorlib.dll>
#using <system.dll>
#using <system.messaging.dll>

using namespace System;
using namespace System::Messaging;

// This example performs asynchronous peek operation
// processing.
//*************************************************

__gc class MyNewQueue 
{
// Provides an event handler for the PeekCompleted
// event.
public:
    static void MyPeekCompleted(Object* source, PeekCompletedEventArgs* asyncResult) 
    {
        // Connect to the queue.
        MessageQueue* mq = dynamic_cast<MessageQueue*>(source);

        // End the asynchronous peek operation.
        Message* m = mq->EndPeek(asyncResult->AsyncResult);

        // Display message information on the screen.
        Console::WriteLine(S"Message: {0}", static_cast<String*>(m->Body));

        // Restart the asynchronous peek operation.
        mq->BeginPeek();

        return; 
    }
};

// Provides an entry point into the application.
//         

int main() 
{
    // Create an instance of MessageQueue. Set its formatter.
    MessageQueue* myQueue = new MessageQueue(S".\\myQueue");

    Type* p __gc[] = new Type* __gc[1];
    p[0] = __typeof(String);
    myQueue->Formatter = new XmlMessageFormatter( p );

    // Add an event handler for the PeekCompleted event.
    myQueue->PeekCompleted += new PeekCompletedEventHandler(0, MyNewQueue::MyPeekCompleted);

    // Begin the asynchronous peek operation.
    myQueue->BeginPeek();

    // Do other work on the current thread.

    return 0;
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Messaging

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

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

See Also

System.Messaging Namespace | MessageQueue | ReceiveCompletedEventHandler | PeekCompletedEventArgs | Events and Delegates

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