Develop Reference

Deserialize an object in RabbitMQ

I have an object I'm sending on a queue that is an object. I have another queue that reads that queue. I can read the data from that queue in the form of a string but I want to deserialize it as the object I sent.
I've tried to format it a few ways and cast the message string received as the object but its not correct.
Console.WriteLine("Listening for messages");
_model.BasicQos(0, 1, false);
Subscription _subscription = new Subscription(_model, QueueName, false);
while (true)
{
Thread.Sleep(2000);
//Get next message
var deliveryArgs = _subscription.Next();
//Deserialize message
var message = System.Text.Encoding.Default.GetString(deliveryArgs.Body);
var t = (MyMessageObject)_subscription.Queue.Dequeue().Body.Deserialize(typeof(MyMessageObject));
var t2 = (MyMessageObject)deliveryArgs.Body.Deserialize(typeof(MyMessageObject));
Console.WriteLine("<=== Received {0} {1}", t.myId, t.myAmount);
//Acknowledge message is processed
_subscription.Ack(deliveryArgs);

I found the solution:
var message = (object)deliveryArgs.Body.DeSerialize(typeof(object));
Just need to cast to what ever your object is.

How to retrieve Dead Letter Queue count?

Question
How do i get the dead letter queue length without receiving each message and counting how many message I received?
My Current Implementation
public int GetDeadLetterQueueCount()
{
//Ref:http://stackoverflow.com/questions/22681954/how-do-you-access-the-dead-letter-sub-queue-on-an-azure-subscription
MessagingFactory factory = MessagingFactory.CreateFromConnectionString(CloudConnectionString);
QueueClient deadLetterClient = factory.CreateQueueClient(QueueClient.FormatDeadLetterPath(_QueueClient.Path), ReceiveMode.PeekLock);
BrokeredMessage receivedDeadLetterMessage;
List<string> lstDeadLetterQueue = new List<string>();
// Ref: https://code.msdn.microsoft.com/Brokered-Messaging-Dead-22536dd8/sourcecode?fileId=123792&pathId=497121593
// Log the dead-lettered messages that could not be processed:
while ((receivedDeadLetterMessage = deadLetterClient.Receive(TimeSpan.FromSeconds(10))) != null)
{
lstDeadLetterQueue.Add(String.Format("DeadLettering Reason is \"{0}\" and Deadlettering error description is \"{1}\"",
receivedDeadLetterMessage.Properties["DeadLetterReason"],
receivedDeadLetterMessage.Properties["DeadLetterErrorDescription"]));
var locktime = receivedDeadLetterMessage.LockedUntilUtc;
}
return lstDeadLetterQueue.Count;
}
Problem with implementation
Because I am receiving each message in peek and block mode, the messages have a lock duration set. During this time i cannot receive or even see the messages again until this time period has timed out.
There must be an easier way of just getting the count without having to poll the queue?
I do not want to consume the messages either, i would just like the count of the total amount.

You can use the NamespaceManager's GetQueue() method which has a MessageCountDetails property, which in turn has a DeadLetterMessageCount property. Something like:
var namespaceManager = Microsoft.ServiceBus.NamespaceManager.CreateFromConnectionString("<CONN_STRING>");
var messageDetails = namespaceManager.GetQueue("<QUEUE_NAME>").MessageCountDetails;
var deadLetterCount = messageDetails.DeadLetterMessageCount;

Azure service bus queue Message deadlettered after Message.Abandon

I am trying out Azure Service Bus queue. I have the below code:
Queue send:
string strConnectionString = ConfigurationManager.AppSettings["Microsoft.ServiceBus.ConnectionString"];
var namespaceManager = NamespaceManager.CreateFromConnectionString(strConnectionString);
if (!namespaceManager.QueueExists("Test"))
{
QueueDescription qD = new QueueDescription("Test");
qD.DefaultMessageTimeToLive = new TimeSpan(05, 00, 00);
qD.LockDuration = new TimeSpan(00, 02, 30);
qD.MaxSizeInMegabytes = 5120;
namespaceManager.CreateQueue(qD);
}
if (namespaceManager.QueueExists("Test"))
{
QueueClient client = QueueClient.CreateFromConnectionString(strConnectionString, "Test", ReceiveMode.PeekLock);
var qMessage = Console.ReadLine();
using (MemoryStream strm = new MemoryStream(Encoding.UTF8.GetBytes(qMessage)))
{
BrokeredMessage bMsg = new BrokeredMessage(strm);
bMsg.MessageId = Guid.NewGuid().ToString();
bMsg.TimeToLive = new TimeSpan(05, 00, 00);
client.Send(bMsg);
Console.WriteLine("Message sent");
}
}
Console.ReadLine();
The receive code:
string strConnectionString = ConfigurationManager.AppSettings["Microsoft.ServiceBus.ConnectionString"];
var namespaceManager = NamespaceManager.CreateFromConnectionString(strConnectionString);
if (namespaceManager.QueueExists("Test"))
{
QueueClient client = QueueClient.CreateFromConnectionString(strConnectionString, "Test",ReceiveMode.PeekLock);
if (client != null)
{
OnMessageOptions options = new OnMessageOptions();
options.AutoComplete = false;
options.AutoRenewTimeout = TimeSpan.FromSeconds(31);
client.OnMessage((message) =>
{
Console.WriteLine(message.State.ToString());
Console.WriteLine("Message Id: " + message.MessageId);
Stream stream = message.GetBody<Stream>();
StreamReader reader = new StreamReader(stream);
Console.WriteLine("Message: " + reader.ReadToEnd());
Console.WriteLine("***************");
message.Abandon();
});
Console.ReadLine();
}
}
I see that whenever I call Abandon, the message is getting DeadLettered. My assumption was that it should get Active and can be picked up by another client.

Your understanding of BrokeredMessage.Abandon Api is correct. It is intended to abandon the peek-lock acquired on the message (but NOT abandon the message itself) and hence, makes it available for other receivers to pick the Message up.
Here's how we envisioned different states of a peek-lock'ed message:
Basics first
The 'Why': If Customers need Competing-Consumer (Job-Queue) semantics - where they need multiple workers to simultaneously process different messages from a Queue with Exactly-Once guarantee - then they use the ReceiveMode.PeekLock. In this model, each worker (the queue receiver) needs a way to communicate the Progress of its Current message (Job) to other workers. Hence, brokeredMessage provides 4 functions to express the states.
The 'What':
if a message is successfully processed by the current Worker - call BrokeredMessage.Complete()
if the BrokeredMessage cannot be processed by the current worker, and want the processing to be retried on another Worker - then, Abandon the message. But, the catch here is: lets say, there are 2 workers and each of them thinks that the other one can process this message and calls Abandon - soon they will end up in an Infinite loop of retry'ing to process just that message! So, to avoid this situation, we provided a Configuration called MaxDeliveryCount on QueueDescription. This setting guards the limit on the number of times the message is delivered from the Queue to receiver. In the above example, Each time you received (and abandoned) the message, the 'deliveryCount' on the ServiceBus service is incremented. When it reaches 10 - the message has hit max no. of deliveries and hence, will be deadlettered.
if the current receiver (worker) knows for sure, that, this message cannot be processed, BrokeredMessage.DeadLetter(). The goal here is to let the consuming application Audit the dead-lettered messages regularly.
if the current receiver (worker) cannot process this message, but, knows that this message can be processed at a later point of time BrokeredMessage.Defer().
HTH!
Sree

Windows Non-WCF Service Moving Transacted MSMQ Message to Failed Queue

I have a legacy Windows service running on Server 2008 that reads messages from a Transactional MSMQ Queue. This is not configured as a WCF service.
We are wanting to improve the handling of failed and poison messages in code (C# 4.0) by catching custom exceptions and sending the related message to a separate 'failed' or 'poison' queue depending upon the type of exception thrown.
I can't get the Catch code to send the message to the separate queue - it disappears from the original queue (as desired!) but doesn't show up in the 'failed' queue.
For testing all of the queues have no Authentication required and permissions are set to allow Everyone to do everything.
Clearly something is missing or wrong and I suspect it is transaction related, but I can't see it. Or perhaps this is not possible the way I am trying to do it ?
Any guidance / suggestions appreciated!
Our simplified PeekCompleted Event code:
private void MessageReceived(object sender, PeekCompletedEventArgs e)
{
using (TransactionScope txnScope = new TransactionScope())
{
MyMessageType currentMessage = null;
MessageQueue q = ((MessageQueue)sender);
try
{
Message queueMessage = q.EndPeek(e.AsyncResult);
currentMessage = (FormMessage)queueMessage.Body;
Processor distributor = new Processor();
Processor.Process(currentMessage); // this will throw if need be
q.ReceiveById(e.Message.Id);
txnScope.Complete();
q.BeginPeek();
}
catch (MyCustomException ex)
{
string qname = ".\private$\failed";
if (!MessageQueue.Exists(qname)){
MessageQueue.Create(qname , true);
}
MessageQueue fq = new MessageQueue(qname){
Formatter = new BinaryMessageFormatter()
};
System.Messaging.Message message2 = new System.Messaging.Message{
Formatter = new BinaryMessageFormatter(),
Body = currentMessage,
Label = "My Failed Message";
};
fq.Send(message2); //send to failed queue
q.ReceiveById(e.Message.Id); //off of original queue
txnScope.Complete(); // complete the trx
_queue.BeginPeek(); // next or wait
}
//other catches handle any cases where we want to tnxScope.Dispose()
EDIT : October 8, 2013
Hugh's answer below got us on the right track. Inside the Catch block the Failed Queue was already created as transactional
MessageQueue.Create(qname , true);
but the Send needed a TransactionType parameter
fq.Send(message2,MessageQueueTransactionType.Single);
That did the trick. Thanks Hugh!

If the message is disappearing from your original queue then that means your code is reaching the second scope.Complete() (in your catch block).
This means the problem has to do with your send to the error queue.
I would suggest that you need to create the queue as transactional because you are sending from within a scope.
MessageQueue fq = new MessageQueue(qname, true){
Formatter = new BinaryMessageFormatter()
};
Then you need to do a transactional send:
fq.Send(message2, Transaction.Current);
See if this works.

Unable to get queue length / message count from Azure

I have a Use Case where I need to queue a select number of messages when the current queue length drops below a specified value. Since I'm running in Azure, I'm trying to use the RetrieveApproximateMessageCount() method to get the current message count. Everytime I call this I get an exception stating StorageClientException: The specified queue does not exist.. Here is a review of what I've done:
Created the queue in the portal and have successfully queued messages to it.
Created the storage account in the portal and it is in the Created/Online state
Coded the query as follows (using http and https options):
var storageAccount = new CloudStorageAccount(
new StorageCredentialsAccountAndKey(_messagingConfiguration.StorageName.ToLower(),
_messagingConfiguration.StorageKey), false);
var queueClient = storageAccount.CreateCloudQueueClient();
var queue = queueClient.GetQueueReference(queueName.ToLower());
int messageCount;
try
{
messageCount = queue.RetrieveApproximateMessageCount();
}
catch (Exception)
{
//Booom!!!!! in every case
}
// ApproximateMessageCount is always null
messageCount = queue.ApproximateMessageCount == null ? 0 : queue.ApproximateMessageCount.Value;
I've confirmed the name is cased correctly with not special characters, numbers, or spaces and the resulting queue Url appears as though its correct formed based on the API documentations (e.g. http://myaccount.queue.core.windows.net/myqueue)
Can anyone help shed some light on what I'm doing wrong.
EDIT
I've confirmed that using the MessageFactory I can create a QueueClient and then enqueue/dequeue messages successfully. When I use the CloudStorageAccount the queue is never present so the counts and GetMessage routines never work. I am guessing these are not the same thing??? Assuming, I'm correct, what I need is to measure the length of the Service Bus Queue. Is that possible?

RetrieveApproximateMessageCount() has been deprecated
if you want to use ApproximateMessageCount to get result try this
CloudQueue q = queueClient.GetQueueReference(QUEUE_NAME);
q.FetchAttributes();
qCnt = q.ApproximateMessageCount;

The CloudQueue method has been deprecated (along with the v11 SDK).
The following snippet is the current replacement (from the Azure Docs)
//-----------------------------------------------------
// Get the approximate number of messages in the queue
//-----------------------------------------------------
public void GetQueueLength(string queueName)
{
// Get the connection string from app settings
string connectionString = ConfigurationManager.AppSettings["StorageConnectionString"];
// Instantiate a QueueClient which will be used to manipulate the queue
QueueClient queueClient = new QueueClient(connectionString, queueName);
if (queueClient.Exists())
{
QueueProperties properties = queueClient.GetProperties();
// Retrieve the cached approximate message count.
int cachedMessagesCount = properties.ApproximateMessagesCount;
// Display number of messages.
Console.WriteLine($"Number of messages in queue: {cachedMessagesCount}");
}
}
https://learn.microsoft.com/en-us/azure/storage/queues/storage-dotnet-how-to-use-queues?tabs=dotnet#get-the-queue-length