Skip to main content

Should(n't) peek and lock a message from Azure Service Bus for 5 hours

Let’s talk about anti-patterns when business drives technology.
Imagine that you are working for a bank where you implement a message base communication build on top of Azure Service Bus.
Everything works great for a few years until one of the business stakeholders implement their business application in such a way that a message needs to be locked for 5 hours. They used competing consumer pattern to support business requirements -  to wait for confirmation from external users for a maximum of 5 hours. If there is no confirmation from the users, the request (message) shall be processed one more time.

Issues
There are some mistakes in the way how business reqs was implemented:
(1) The maximum Peek and Lock of a message from Azure Service Bus is 5 minutes. It is impossible to peek a message from a subscription or queue and do a lock for 5 hours.
(2) It does not clearly define the number of retries. If the user(s) does not confirm the action would mean that the message will be available over and over again. They are blocking other messages to be processed and increase the load of the system. You would need to specify a maximum number of retries before pushing the message to dead-letter queues.
For actions that take longer than 1 or 2 minutes, Peek and Lock on top of Azure Service Bus might not be the best solution. You would need to challenge yourself and see if an ESB is the best option for your needs.

Alternative solution
The advantage with Peek and Lock and Azure Service Bus is reliability. When content it is not processed with success by the consumer, the message is available again in the subscription for another try. The tricky part is to find a simple way to have the same quality attribute at a low cost.
After discussion with the business stakeholder, we identified that the maximum retry times is 3, and because of multiple consumers, Azure Service Bus is one of the preferred solutions. Azure Cosmos DB is reliable storage that could be used in combination with TTL feature.
We could have a system that consumes messages from Azure Service Bus in Peek-and-Lock mode. The messages are pushed to Azure Cosmos DB as a document with TTL (Time To Live) set to 5 hours. This means that the content is stored for 5 hours in Cosmos DB. After 5 hours, if the user or a 3rd party confirm the action, the message can be automatically removed from the Azure Cosmos DB.
An Azure Function can be registered to receive a notification when the TTL expires, which can push the message back to the Azure Service Bus. At this point, the retry counter can be incremented by 1. When the retry counter becomes equal to 3, we can log an issue and generate a business alert.

Things to consider:
(1) The role of Azure Service Bus to manage multiple consumers is crucial. Implementing it directly on a NoSQL solution it is error prompt.
(2) We still use Peek and Lock at the consumer level to ensure that we have a reliable way to process the message and send it to Azure Cosmos DB.
(3) Any fatal error at Azure Functions level needs to be managed by ourselves, and it is the only location where we could lose a message because of an application error. The Service Bus consumer is protected by Peek and Lock.

In the below diagrams, you can find a high-level overview of the solution.




Conclusion
Of course, we might find another solution. For the current case, I consider this one of the most simple solutions that have a low impact on implementation cost and without affecting the operations activities. Both Azure Service Bus and Azure Cosmos DB are reliable storages for messages and documents and Peek and Lock combined with TTL help us to connect the end-to-end flow.

Comments

Popular posts from this blog

Windows Docker Containers can make WIN32 API calls, use COM and ASP.NET WebForms

After the last post , I received two interesting questions related to Docker and Windows. People were interested if we do Win32 API calls from a Docker container and if there is support for COM. WIN32 Support To test calls to WIN32 API, let’s try to populate SYSTEM_INFO class. [StructLayout(LayoutKind.Sequential)] public struct SYSTEM_INFO { public uint dwOemId; public uint dwPageSize; public uint lpMinimumApplicationAddress; public uint lpMaximumApplicationAddress; public uint dwActiveProcessorMask; public uint dwNumberOfProcessors; public uint dwProcessorType; public uint dwAllocationGranularity; public uint dwProcessorLevel; public uint dwProcessorRevision; } ... [DllImport("kernel32")] static extern void GetSystemInfo(ref SYSTEM_INFO pSI); ... SYSTEM_INFO pSI = new SYSTEM_INFO(

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

Today blog post will be started with the following error when running DB tests on the CI machine: threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See http://go.microsoft.com/fwlink/?LinkId=260882 for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration: TeamCity .NET 4.51 EF 6.0.2 VS2013 It see

Navigating Cloud Strategy after Azure Central US Region Outage

 Looking back, July 19, 2024, was challenging for customers using Microsoft Azure or Windows machines. Two major outages affected customers using CrowdStrike Falcon or Microsoft Azure computation resources in the Central US. These two outages affected many people and put many businesses on pause for a few hours or even days. The overlap of these two issues was a nightmare for travellers. In addition to blue screens in the airport terminals, they could not get additional information from the airport website, airline personnel, or the support line because they were affected by the outage in the Central US region or the CrowdStrike outage.   But what happened in reality? A faulty CrowdStrike update affected Windows computers globally, from airports and healthcare to small businesses, affecting over 8.5m computers. Even if the Falson Sensor software defect was identified and a fix deployed shortly after, the recovery took longer. In parallel with CrowdStrike, Microsoft provided a too