Acknowledgment Enumeration

 
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Specifies the result of an attempted message delivery.

Namespace:   System.Messaging
Assembly:  System.Messaging (in System.Messaging.dll)

public enum Acknowledgment

Member nameDescription
AccessDenied

A negative arrival acknowledgment indicating that the sending application does not have the necessary rights to send a message to the destination queue.

BadDestinationQueue

A negative arrival acknowledgment indicating that the destination queue is not available to the sending application.

BadEncryption

A negative arrival acknowledgment indicating that the destination queue manager could not decrypt a private message.

BadSignature

A negative arrival acknowledgment indicating that the original message's digital signature is not valid and could not be authenticated by Message Queuing.

CouldNotEncrypt

A negative arrival acknowledgment indicating that the source queue manager could not encrypt a private message.

HopCountExceeded

A negative arrival acknowledgment indicating that the original message's hop count (which indicates the number of intermediate servers) was exceeded.

None

The message is not an acknowledgment message.

NotTransactionalMessage

A negative arrival acknowledgment indicating that a non-transactional message was sent to a transactional queue.

NotTransactionalQueue

A negative arrival acknowledgment indicating that a transactional message was sent to a non-transactional queue.

Purged

A negative arrival acknowledgment indicating that the message was purged before reaching its destination queue.

QueueDeleted

A negative read acknowledgment indicating that the queue was deleted before the message could be read.

QueueExceedMaximumSize

A negative arrival acknowledgment indicating that the original message was not delivered because its destination queue is full.

QueuePurged

A negative read acknowledgment indicating that the queue was purged before the message could be read.

ReachQueue

A positive arrival acknowledgment indicating that the original message reached its destination queue.

ReachQueueTimeout

A negative arrival acknowledgment indicating that the time-to-reach-queue or time-to-be-received timer expired before the original message could reach the destination queue.

Receive

A positive read acknowledgment indicating that the original message was received by the receiving application.

ReceiveTimeout

A negative read acknowledgment indicating that the original message was not received from the queue before its time-to-be-received timer expired.

The Acknowledgment class defines the types of acknowledgment messages that Message Queuing posts in the administration queue and the conditions that cause an acknowledgment message to be sent. Acknowledgment types can be divided broadly into four groups: positive arrival acknowledgments, positive read acknowledgments, negative arrival acknowledgments, and negative read acknowledgments.

The administration queue associated with message is specified in the Message.AdministrationQueue property.

Message Queuing sets the Message.Acknowledgment property to one of the Acknowledgment enumeration values when it creates an acknowledgment message. The Message.Acknowledgment property value is typically meaningful only when the instance refers to a system-sent acknowledgment message. Reading the Message.Acknowledgment property for a message other than an acknowledgment message throws an exception.

Message Queuing does not send an acknowledgment message unless the sending application requests that it do so. Your application makes this request by setting the appropriate value for the Message.AcknowledgeType property. Message Queuing sends all acknowledgment messages to the administration queue specified in the AdministrationQueue property of the original Message.

The following code example sends and receives a message containing an order to and from a queue. It specifically requests a positive acknowledgment when the original message reaches or is retrieved from the queue.

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 sends and receives a message from
		// a queue.
		//**************************************************

		public static void Main()
		{
			// Create a new instance of the class.
			MyNewQueue myNewQueue = new MyNewQueue();

			// Create new queues.
			CreateQueue(".\\myQueue");
			CreateQueue(".\\myAdministrationQueue");

			// Send messages to a queue.
			myNewQueue.SendMessage();

			// Receive messages from a queue.
			string messageId = myNewQueue.ReceiveMessage(); 

			// Receive acknowledgment message.
			if(messageId != null)
			{
				myNewQueue.ReceiveAcknowledgment(messageId, ".\\myAdministrationQueue");
			}

			return;
		}

		//**************************************************
		// Creates a new queue.
		//**************************************************

		public static void CreateQueue(string queuePath)
		{
			try	
			{
				if(!MessageQueue.Exists(queuePath))
				{
					MessageQueue.Create(queuePath);
				}
				else
				{
					Console.WriteLine(queuePath + " already exists.");
				}
			}
			catch (MessageQueueException e)
			{
				Console.WriteLine(e.Message);
			}

		}


		//**************************************************
		// Sends a string message to a queue.
		//**************************************************

		public void SendMessage()
		{

			// Connect to a queue on the local computer.
			MessageQueue myQueue = new MessageQueue(".\\myQueue");

			// Create a new message.
			Message myMessage = new Message("Original Message"); 

			myMessage.AdministrationQueue = new MessageQueue(".\\myAdministrationQueue");
			myMessage.AcknowledgeType = AcknowledgeTypes.PositiveReceive | AcknowledgeTypes.PositiveArrival;

			// Send the Order to the queue.
			myQueue.Send(myMessage);

			return;
		}


		//**************************************************
		// Receives a message containing an Order.
		//**************************************************

		public  string ReceiveMessage()
		{
			// Connect to the a queue on the local computer.
			MessageQueue myQueue = new MessageQueue(".\\myQueue");

			myQueue.MessageReadPropertyFilter.CorrelationId = true;


			// Set the formatter to indicate body contains an Order.
			myQueue.Formatter = new XmlMessageFormatter(new Type[]
				{typeof(string)});

			string returnString = null;

			try
			{
				// Receive and format the message. 
				Message myMessage =	myQueue.Receive(); 


				// Display message information.
				Console.WriteLine("____________________________________________");
				Console.WriteLine("Original message information--");
				Console.WriteLine("Body: " +myMessage.Body.ToString());
				Console.WriteLine("Id: " + myMessage.Id.ToString());
				Console.WriteLine("____________________________________________");

				returnString =  myMessage.Id;

			}

			catch (MessageQueueException)
			{
				// Handle Message Queuing exceptions.
			}

			// Handle invalid serialization format.
			catch (InvalidOperationException e)
			{
				Console.WriteLine(e.Message);
			}

			// Catch other exceptions as necessary.

			return returnString;
		}

		//**************************************************
		// Receives a message containing an Order.
		//**************************************************

		public void ReceiveAcknowledgment(string messageId, string queuePath)
		{
			bool found = false;
			MessageQueue queue = new MessageQueue(queuePath);
			queue.MessageReadPropertyFilter.CorrelationId = true;
			queue.MessageReadPropertyFilter.Acknowledgment = true;

			try
			{
				while(queue.PeekByCorrelationId(messageId) != null)
				{
					Message myAcknowledgmentMessage = queue.ReceiveByCorrelationId(messageId);

					// Output acknowledgment message information. The correlation Id is identical
					// to the id of the original message.
					Console.WriteLine("Acknowledgment Message Information--");
					Console.WriteLine("Correlation Id: " + myAcknowledgmentMessage.CorrelationId.ToString());
					Console.WriteLine("Id: " + myAcknowledgmentMessage.Id.ToString());
					Console.WriteLine("Acknowledgment Type: " + myAcknowledgmentMessage.Acknowledgment.ToString());
					Console.WriteLine("____________________________________________");

					found = true;
				}
			}
			catch (InvalidOperationException e)
			{ 
				// This exception would be thrown if there is no (further) acknowledgment message
				// with the specified correlation Id. Only output a message if there are no messages;
				// not if the loop has found at least one.
				if(found == false)
				{	
					Console.WriteLine(e.Message);
				}

				// Handle other causes of invalid operation exception.
			}

		}
	}
}

.NET Framework
Available since 1.1
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