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Queue

  • It can store more than 80 GB messages in a queue (different from azure storage queue)
  • Under Service Bus Explorer you can send, receive or peek messages

Consume methods

  • Peek and Lock

  • Get a message and lock it for the message lock duration

  • Prevents other apps to pick the same message during this time
  • If the app crashes before processing the message then it will be available again in the queue after the lock period

  • Optionally you can "complete" the message to remove it from queue

  • Receive and Delete

  • Get a message and delete is right away from queue

  • If the application crashes before it is processed then the message is lost

Sessions

  • To guarantee the FIFO delivery of messages, you can enable sessions for the queue
  • This is not achievable in Azure Storage Queue

Time to Live

  • Maximum message lifetime
  • If message is not consumed after that period the message is lost

Dead letter queue

  • Messages that couldn't be processed or reached the TTL will fall into the dead letter queue
  • Dead lettering on message expiration can be enabled on the queue overview
  • Messages already in the dead letter queue do not expire
  • To refer to the dead letter queue -> queue-name/$DeadLetterQueue

Duplicate message detection

  • Duplicate detection can be enabled only upon creation of the queue
  • Prevents the scenario when a sender sends a message and it crashes, then sends back the same message again
  • A duplicate time window can be configured. No message can have same messageID in this period. Default of 10 minutes

Message properties

  • Broker/system defined properties

  • Body: message payload

  • ContentType: applicantion/json, applicantion/xml, etc
  • CorrelationId: reference to the original messageId (for example when sending a new response message)
  • MessageId: for duplicate message detection
  • PartitionKey
  • ReplyTo: queue to send the response to (e.g., message acknowledge). The correlationId of the response must contain reference to the messageId of the origin message!
message.ContentType = "application/json";
message.TimeToLive = TimeSpan.FromSeconds(30);
message.MessageId = "1";

  • To have a proper audit trail, you can either:

    • Use the CorrelationId (destination) to map to an existing MessageId (source)
    • Use the ReplyToSessionId (destination) property to map to the SessionID (source)

  • User defined properties

  • Custom properties

message.ApplicationProperties.Add("Department", "HR");
message.ApplicationProperties.Add("School", "USP");
foreach (var key in message.ApplicationProperties.Keys)
  {
    Console.WriteLine(key.ToString());
    Console.WriteLine(message.ApplicationProperties[key].ToString());
  }

Dotnet SDK

  • Nuget Package: Azure.Messaging.ServiceBus
class Program
{
  private static string connectionString = "Endpoint=sb://hvitoi.servicebus.windows.net/;SharedAccessKeyName=Send;SharedAccessKey=shared-access-key;EntityPath=appqueue";
  private static string queueName = "appqueue";
  static void Main(string[] args)
  {
    // Service Bus Client
    ServiceBusClient client = new ServiceBusClient(connectionString);

    // Send messages to Queue
    ServiceBusSender sender = client.CreateSender(queueName);
    List<Order> orders = new List<Order>()
    {
        new Order() {OrderID="O1",Quantity=10,UnitPrice=9.99m},
        new Order() {OrderID="O2",Quantity=15,UnitPrice=10.99m },
        new Order() {OrderID="O3",Quantity=20,UnitPrice=11.99m},
        new Order() {OrderID="O4",Quantity=25,UnitPrice=12.99m},
        new Order() {OrderID="O5",Quantity=30,UnitPrice=13.99m }
    };
    foreach(Order order in orders)
    {
        ServiceBusMessage message = new ServiceBusMessage(order.ToString());
        message.ContentType = "application/json";
        message.TimeToLive = TimeSpan.FromSeconds(30); // override the default TTL of the queue
        message.MessageId = "1"; // Explicitly specify MessageId. If not specified it will generate an UUID
        message.ApplicationProperties.Add("Department", "HR"); // custom key-value property
        sender.SendMessageAsync(message).GetAwaiter().GetResult();
    }
    Console.WriteLine("All of the messages have been sent");

    // Peek and Lock
    ServiceBusReceiver receiver = client.CreateReceiver(queueName, new ServiceBusReceiverOptions() { ReceiveMode = ServiceBusReceiveMode.PeekLock });
    ServiceBusReceivedMessage message = receiver.ReceiveMessageAsync().GetAwaiter().GetResult(); // ReceiveMessagesAsync(3) for multiple messages and omit the type
    Console.WriteLine(message.Body);
    Console.WriteLine($"The Sequence number is {message.SequenceNumber}");
    receiver.CompleteMessageAsync(message); // optionally remove message from queue after it has been processed

    // Receive and Delete
    ServiceBusReceiver receiver = client.CreateReceiver(queueName, new ServiceBusReceiverOptions() { ReceiveMode = ServiceBusReceiveMode.ReceiveAndDelete });
    ServiceBusReceivedMessage message = receiver.ReceiveMessageAsync().GetAwaiter().GetResult();
    Console.WriteLine(message.Body);
    Console.WriteLine($"The Sequence number is {message.SequenceNumber}");

    // Get Application properties
    ServiceBusReceiver receiver = client.CreateReceiver(queueName, new ServiceBusReceiverOptions() { ReceiveMode = ServiceBusReceiveMode.PeekLock });
    ServiceBusReceivedMessage message = receiver.ReceiveMessageAsync().GetAwaiter().GetResult();
    Console.WriteLine(message.Body);
    foreach (var key in message.ApplicationProperties.Keys)
    {
      Console.WriteLine(key.ToString());
      Console.WriteLine(message.ApplicationProperties[key].ToString());
    }
  }
}