MessageQueue.EndReceive Method
Completes the specified asynchronous receive operation.
Assembly: System.Messaging (in System.Messaging.dll)
'Declaration Public Function EndReceive ( _ asyncResult As IAsyncResult _ ) As Message 'Usage Dim instance As MessageQueue Dim asyncResult As IAsyncResult Dim returnValue As Message returnValue = instance.EndReceive(asyncResult)
Parameters
- asyncResult
- Type: System.IAsyncResult
The IAsyncResult that identifies the asynchronous receive operation to finish and from which to retrieve an end result.
Return Value
Type: System.Messaging.MessageThe Message associated with the completed asynchronous operation.
| Exception | Condition |
|---|---|
| ArgumentNullException | The asyncResult parameter is Nothing. |
| ArgumentException | The syntax of the asyncResult parameter is not valid. |
| MessageQueueException | An error occurred when accessing a Message Queuing method. |
When the ReceiveCompleted event is raised, EndReceive(IAsyncResult) completes the operation that was initiated by the BeginReceive call. To do so, EndReceive(IAsyncResult) receives the message.
BeginReceive can specify a time-out, which causes the ReceiveCompleted event to be raised if the time-out occurs before a message appears in the queue. When a time-out occurs without a message arriving in the queue, a subsequent call to EndReceive(IAsyncResult) throws an exception.
EndReceive(IAsyncResult) is used to read (removing from the queue) the message that caused the ReceiveCompleted event to be raised.
If you want to continue to asynchronously receive messages, you can again call BeginReceive after calling EndReceive(IAsyncResult).
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 chains asynchronous requests. It assumes there is a queue on the local computer called "myQueue". The Main function begins the asynchronous operation that is handled by the MyReceiveCompleted routine. MyReceiveCompleted processes the current message and begins a new asynchronous receive operation.
Imports System Imports System.Messaging Imports System.Threading ' Provides a container class for the example. Public Class MyNewQueue ' Define static class members. Private Shared signal As New ManualResetEvent(False) Private Shared count As Integer = 0 ' Provides an entry point into the application. ' ' This example performs asynchronous receive ' 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 ReceiveCompleted event. AddHandler myQueue.ReceiveCompleted, AddressOf _ MyReceiveCompleted ' Begin the asynchronous receive operation. myQueue.BeginReceive() signal.WaitOne() ' Do other work on the current thread. Return End Sub 'Main ' Provides an event handler for the ReceiveCompleted ' event. Private Shared Sub MyReceiveCompleted(ByVal [source] As _ [Object], ByVal asyncResult As ReceiveCompletedEventArgs) Try ' Connect to the queue. Dim mq As MessageQueue = CType([source], MessageQueue) ' End the asynchronous receive operation. Dim m As Message = _ mq.EndReceive(asyncResult.AsyncResult) count += 1 If count = 10 Then signal.Set() End If ' Restart the asynchronous receive operation. mq.BeginReceive() Catch ' Handle sources of MessageQueueException. ' Handle other exceptions. End Try Return End Sub 'MyReceiveCompleted End Class 'MyNewQueue
#using <mscorlib.dll>
#using <system.dll>
#using <system.messaging.dll>
using namespace System;
using namespace System::Messaging;
using namespace System::Threading;
__gc class MyNewQueue
{
public:
// Define static class members.
static ManualResetEvent* signal = new ManualResetEvent(false);
static int count = 0;
// Provides an event handler for the ReceiveCompleted
// event.
public:
static void MyReceiveCompleted(Object* source,
ReceiveCompletedEventArgs* asyncResult)
{
try
{
// Connect to the queue.
MessageQueue* mq = dynamic_cast<MessageQueue*>(source);
// End the asynchronous receive operation.
mq->EndReceive(asyncResult->AsyncResult);
count += 1;
if (count == 10)
{
signal->Set();
}
// Restart the asynchronous receive operation.
mq->BeginReceive();
}
catch (MessageQueueException*)
{
// Handle sources of MessageQueueException.
}
// Handle other exceptions.
return;
}
};
// Provides an entry point into the application.
//
// This example performs asynchronous receive
// operation processing.
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 ReceiveCompleted event.
myQueue->ReceiveCompleted += new ReceiveCompletedEventHandler(0, MyNewQueue::MyReceiveCompleted);
// Begin the asynchronous receive operation.
myQueue->BeginReceive();
MyNewQueue::signal->WaitOne();
// 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.