MessageQueue.PeekCompleted Event
Occurs when a message is read without being removed from the queue. This is a result of the asynchronous operation, BeginPeek.
Assembly: System.Messaging (in System.Messaging.dll)
BeginPeek is used in asynchronous processing to raise the PeekCompleted event when a message is available in the queue.
EndPeek(IAsyncResult) is used to complete the operation initiated by a call to BeginPeek and peek the message when the PeekCompleted event is raised.
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.
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
#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;
}
- Full trust for the immediate caller. This member cannot be used by partially trusted code. For more information, see Using Libraries from Partially Trusted Code.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.