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Competing Consumers Pattern

Competing Consumers Pattern

Owned by thierry sinassamy
Last updated: Aug 27, 2024
2 min read

Details in Competing Consumers pattern - Azure Architecture Center | Microsoft Learn

Problem

  • App running in the cloud expecting to handle a large number of requests :

    • not handle synchronously, rather handle them asynchronously.

  • At peak hours, using a single instance can cause the instance to become flooded with requests.

Solution

  • Using multiple instances to make the workload to be load balanced across consumers to prevent an instance to become the bottleneck.

    • Need a message queue to distribute work to instances of a service and to avoid timeout.

image-20240827-143440.png
Diagram from Micosoft Documentation

Competing Consumers In Practice

image-20240827-150233.png

 

Example of Code in C#

string connectionString = "<connection_string>"; string queueName = "<queue_name>"; // since ServiceBusClient implements IAsyncDisposable we create it with "await using" await using var client = new ServiceBusClient(connectionString); // create the sender ServiceBusSender sender = client.CreateSender(queueName); // create a message that we can send. UTF-8 encoding is used when providing a string. ServiceBusMessage message = new ServiceBusMessage("Hello world!"); // send the message await sender.SendMessageAsync(message); // create a receiver that we can use to receive the message ServiceBusReceiver receiver = client.CreateReceiver(queueName); // the received message is a different type as it contains some service set properties ServiceBusReceivedMessage receivedMessage = await receiver.ReceiveMessageAsync(); // get the message body as a string string body = receivedMessage.Body.ToString(); Console.WriteLine(body);