MessageQueue.EndPeek Method
Assembly: System.Messaging (in system.messaging.dll)
'Declaration Public Function EndPeek ( _ asyncResult As IAsyncResult _ ) As Message 'Usage Dim instance As MessageQueue Dim asyncResult As IAsyncResult Dim returnValue As Message returnValue = instance.EndPeek(asyncResult)
public Message EndPeek ( IAsyncResult asyncResult )
public function EndPeek ( asyncResult : IAsyncResult ) : Message
Parameters
- asyncResult
The IAsyncResult that identifies the asynchronous peek operation to finish and from which to retrieve an end result.
Return Value
The Message associated with the completed asynchronous operation.When the PeekCompleted event is raised, EndPeek completes the operation that was initiated by the BeginPeek call. To do so, EndPeek peeks the message.
BeginPeek can specify a time-out, which causes the PeekCompleted event to be raised if the time-out occurs before a message appears in the queue. In this case, the IsCompleted property of the asyncResult parameter is set to true, but no message is associated with the operation. When a time-out occurs without a message arriving in the queue, a subsequent call to EndPeek throws an exception.
EndPeek is used to read the message that caused the PeekCompleted event to be raised.
If you want to continue to asynchronously peek messages, you can again call BeginPeek after calling EndPeek.
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 | Yes |
| Remote computer | No |
| Remote computer and direct format name | Yes |
The following code example creates an event handler named MyPeekCompleted, attaches it to the PeekCompleted event handler delegate, and calls BeginPeek to initiate an asynchronous peek operation on the queue that is located at the path ".\myQueue". When a PeekCompleted event is raised, the example peeks the message and writes its body to the screen. The example then calls BeginPeek again to initiate a new asynchronous peek operation.
Imports System Imports System.Messaging ' Provides a container class for the example. 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
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 performs asynchronous peek operation
// processing.
//**************************************************
public static void main(String[] args)
{
// Create an instance of MessageQueue. Set its formatter.
MessageQueue myQueue = new MessageQueue(".\\myQueue");
myQueue.set_Formatter(new XmlMessageFormatter(new Type[]
{ String.class.ToType() }));
// Add an event handler for the PeekCompleted event.
myQueue.add_PeekCompleted(new PeekCompletedEventHandler(MyPeekCompleted));
// Begin the asynchronous peek operation.
myQueue.BeginPeek();
// Do other work on the current thread.
return;
} //main
//**************************************************
// 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.get_AsyncResult());
// Display message information on the screen.
Console.WriteLine("Message: " + (String)(m.get_Body()));
// Restart the asynchronous peek operation.
mq.BeginPeek();
return;
} //MyPeekCompleted
} //MyNewQueue
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.