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MessageQueue.BeginReceive Method

Initiates an asynchronous receive operation by telling Message Queuing to begin receiving a message and notify the event handler when finished.

Overload List

Initiates an asynchronous receive operation that has no time-out. The operation is not complete until a message becomes available in the queue.

[Visual Basic] Overloads Public Function BeginReceive() As IAsyncResult
[C#] public IAsyncResult BeginReceive();
[C++] public: IAsyncResult* BeginReceive();
[JScript] public function BeginReceive() : IAsyncResult;

Initiates an asynchronous receive operation that has a specified time-out. The operation is not complete until either a message becomes available in the queue or the time-out occurs.

[Visual Basic] Overloads Public Function BeginReceive(TimeSpan) As IAsyncResult
[C#] public IAsyncResult BeginReceive(TimeSpan);
[C++] public: IAsyncResult* BeginReceive(TimeSpan);
[JScript] public function BeginReceive(TimeSpan) : IAsyncResult;

Initiates an asynchronous receive operation that has a specified time-out and a specified state object, which provides associated information throughout the operation's lifetime. The operation is not complete until either a message becomes available in the queue or the time-out occurs.

[Visual Basic] Overloads Public Function BeginReceive(TimeSpan, Object) As IAsyncResult
[C#] public IAsyncResult BeginReceive(TimeSpan, object);
[C++] public: IAsyncResult* BeginReceive(TimeSpan, Object*);
[JScript] public function BeginReceive(TimeSpan, Object) : IAsyncResult;

Initiates an asynchronous receive operation that has a specified time-out and a specified state object, which provides associated information throughout the operation's lifetime. This overload receives notification, through a callback, of the identity of the event handler for the operation. The operation is not complete until either a message becomes available in the queue or the time-out occurs.

[Visual Basic] Overloads Public Function BeginReceive(TimeSpan, Object, AsyncCallback) As IAsyncResult
[C#] public IAsyncResult BeginReceive(TimeSpan, object, AsyncCallback);
[C++] public: IAsyncResult* BeginReceive(TimeSpan, Object*, AsyncCallback*);
[JScript] public function BeginReceive(TimeSpan, Object, AsyncCallback) : IAsyncResult;

Example

[Visual Basic, C#, C++] The following 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.

[Visual Basic, C#, C++] Note   This example shows how to use one of the overloaded versions of BeginReceive. For other examples that might be available, see the individual overload topics.
[Visual Basic] 
Imports System
Imports System.Messaging
Imports System.Threading

Namespace MyProject

    '/ <summary>
    '/ Provides a container class for the example.
    '/ </summary>
    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
End Namespace 'MyProject

[C#] 
using System;
using System.Messaging;
using System.Threading;

namespace MyProject
{
    /// <summary>
    /// Provides a container class for the example.
    /// </summary>
    public class MyNewQueue
    {
        // Define static class members.
        static ManualResetEvent signal = new ManualResetEvent(false);
        static int count = 0;

        //**************************************************
        // Provides an entry point into the application.
        //         
        // This example performs asynchronous receive
        // 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 ReceiveCompleted event.
            myQueue.ReceiveCompleted += 
                new ReceiveCompletedEventHandler(MyReceiveCompleted);
            
            // Begin the asynchronous receive operation.
            myQueue.BeginReceive();

            signal.WaitOne();
            
            // Do other work on the current thread.

            return;
        }


        //***************************************************
        // Provides an event handler for the ReceiveCompleted
        // event.
        //***************************************************
        
        private static void MyReceiveCompleted(Object source, 
            ReceiveCompletedEventArgs asyncResult)
        {
            try
            {
                // Connect to the queue.
                MessageQueue mq = (MessageQueue)source;

                // End the asynchronous receive operation.
                Message m = 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; 
        }
    }
}

[C++] 
#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;
}

[Visual Basic, C#, C++] The following example queues asynchronous requests. The call to BeginReceive uses the AsyncWaitHandle in its return value. The Main routine waits for all asynchronous operations to be completed before exiting.

[Visual Basic] 
Imports System
Imports System.Messaging
Imports System.Threading

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 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

            ' Define wait handles for multiple operations.
            Dim waitHandleArray(10) As WaitHandle

            Dim i As Integer
            For i = 0 To 9
                ' Begin asynchronous operations.
                waitHandleArray(i) = _
                    myQueue.BeginReceive().AsyncWaitHandle
            Next i

            ' Specify to wait for all operations to return.
            WaitHandle.WaitAll(waitHandleArray)

            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)

                ' Process the message here.
                Console.WriteLine("Message received.")

            Catch

                ' Handle sources of MessageQueueException.

                ' Handle other exceptions.

            End Try

            Return

        End Sub 'MyReceiveCompleted

    End Class 'MyNewQueue
End Namespace 'MyProject

[C#] 
using System;
using System.Messaging;
using System.Threading;

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 receive
        // 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 ReceiveCompleted event.
            myQueue.ReceiveCompleted += 
                new ReceiveCompletedEventHandler(MyReceiveCompleted);
            
            // Define wait handles for multiple operations.
            WaitHandle[] waitHandleArray = new WaitHandle[10];
            for(int i=0; i<10; i++)
            {
                // Begin asynchronous operations.
                waitHandleArray[i] = 
                    myQueue.BeginReceive().AsyncWaitHandle;
            }

            // Specify to wait for all operations to return.
            WaitHandle.WaitAll(waitHandleArray);
         
            return;
        }


        //***************************************************
        // Provides an event handler for the ReceiveCompleted
        // event.
        //***************************************************
        
        private static void MyReceiveCompleted(Object source, 
            ReceiveCompletedEventArgs asyncResult)
        {
            try
            {
                // Connect to the queue.
                MessageQueue mq = (MessageQueue)source;
                
                // End the asynchronous receive operation.
                Message m = mq.EndReceive(asyncResult.AsyncResult);
        
                // Process the message here.
                Console.WriteLine("Message received.");

            }
            catch(MessageQueueException)
            {
                // Handle sources of MessageQueueException.
            }
            
            // Handle other exceptions.
            
            return; 
        }
    }
}

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

using namespace System;
using namespace System::Messaging;
using namespace System::Threading;

__gc class MyNewQueue 
{
    // 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);

            // Process the message here.
            Console::WriteLine(S"Message received.");

        }
        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);

    // Define wait handles for multiple operations.
    WaitHandle* waitHandleArray[] = new WaitHandle*[10];
    for (int i=0; i<10; i++) 
    {
        // Begin asynchronous operations.
        waitHandleArray->Item[i] = myQueue->BeginReceive()->AsyncWaitHandle;
    }

    // Specify to wait for all operations to return.
    WaitHandle::WaitAll(waitHandleArray);

    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.

See Also

MessageQueue Class | MessageQueue Members | System.Messaging Namespace

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