PeekCompletedEventArgs PeekCompletedEventArgs PeekCompletedEventArgs PeekCompletedEventArgs Class

Definition

Provides data for the PeekCompleted event. When your asynchronous peek operation calls an event handler, an instance of this class is passed to the handler.

public ref class PeekCompletedEventArgs : EventArgs
public class PeekCompletedEventArgs : EventArgs
type PeekCompletedEventArgs = class
    inherit EventArgs
Public Class PeekCompletedEventArgs
Inherits EventArgs
Inheritance
PeekCompletedEventArgsPeekCompletedEventArgsPeekCompletedEventArgsPeekCompletedEventArgs

Examples

The following code example creates an event handler for the PeekCompleted event and associates it with the event delegate by using the PeekCompletedEventHandler. The event handler, MyPeekCompleted, peeks a message and writes its label to the screen.

#using <system.dll>
#using <system.messaging.dll>

using namespace System;
using namespace System::Messaging;

// This example performs asynchronous peek operation
// processing.
//*************************************************
ref class MyNewQueue
{
public:

   // Provides an event handler for the PeekCompleted
   // event.
   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( "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 = gcnew MessageQueue( ".\\myQueue" );
   array<Type^>^p = gcnew array<Type^>(1);
   p[ 0 ] = String::typeid;
   myQueue->Formatter = gcnew XmlMessageFormatter( p );

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

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

   // Do other work on the current thread.
   return 0;
}
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; 
		}
	}
}
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

Remarks

When you use event notification to peek (read without removing) messages asynchronously from the queue, you must create a method that handles your message processing. Your code must call BeginPeek to begin the asynchronous processing. When a message is peeked, your application is notified through the PeekCompleted event. An instance of PeekCompletedEventArgs is passed into the event delegate that calls your event handler. The data associated with the PeekCompleted event is contained in the delegate's AsyncResult parameter.

There are two ways to provide notification of event completion: event notification and callbacks. PeekCompletedEventArgs is used only with event notification. For information comparing callbacks and event notification, see "Events vs. Callbacks" on MSDN.

PeekCompletedEventArgs provides access to the message that initiated the end of the asynchronous peek operation, through the Message member. This is an alternate access to the message, and behaves much the same as a call to MessageQueue.EndPeek.

Properties

AsyncResult AsyncResult AsyncResult AsyncResult

Gets or sets the result of the asynchronous operation requested.

Message Message Message Message

Gets the message associated with the asynchronous peek operation.

Methods

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Creates a shallow copy of the current Object.

(Inherited from Object)
ToString() ToString() ToString() ToString()

Returns a string that represents the current object.

(Inherited from Object)

Applies to

See also