CODEWITHSUNDEEP
c#azureazure-functionsazureservicebus
tokyo0709
tokyo0709

Reputation: 1997

Handling Azure Service Bus Queue messages with Azure function

So we are in the position where we like to offload some processing in our application to give a better user experience while still accomplishing those heavy tasks and have found our way to Azure Service Bus Queues.

I understand how to push data to the queue and the basic idea behind message queues but what I am struggling to understand is how to handle them when they come in. In just thinking about it it sounds like there should be some way to implement and Azure function that listens to whenever a message comes in but how do I do that without constant polling? I understand you can subscribe to the queue with OnMessage but how does that work with an Azure function?

For example currently we are doing something like this,

var client = QueueClient.CreateFromConnectionString(connectionString, queueName);

BrokeredMessage message = new BrokeredMessage();

while ((message = client.Receive(new TimeSpan(hours: 0, minutes: 0, seconds: 30))) != null)
{
    Console.WriteLine(string.Format("Message received: {0}, {1}, {2}", message.SequenceNumber, message.Label, message.MessageId));
    message.Complete();

    Console.WriteLine("Processing message (sleeping...)");
    Thread.Sleep(1000);
}

Console.WriteLine("Finished listening Press ENTER to exit program");
Console.ReadLine();

But in this case we are just simulating polling right? This just doesn't feel like a good solution. Am I thinking about this wrong in my design?

Upvotes: 0

Views: 3492

Answers (1)

Andy T
Andy T

Reputation: 9881

Azure ServiceBus works by pushing new messages to connected clients instead of having the clients polling the queue.

With the ServiceBus API, you could use the OnMessage method to set up a message pump, but if you are using Azure Functions, this is all done for you with the use of a Service Bus trigger.

You simply configure Azure Function to point to the queue you want to listen on. When a new message is added to the queue, your function is triggered, and the message is passed into it.

Take a look at the Service Bus trigger example:

https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-service-bus#trigger-sample

Upvotes: 3

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