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Updating content of messages from Azure Queues

In the era of microservices and cloud, applications contain more and more components and sub-components that are design to do only one thing. All this components needs to communicate between each other in a fast and reliable way.
For communication purpose, different messaging solutions are used. Nowadays, a Enterprise Service Bus solution like Azure Services Bus Topic or BizTalk is normal. For more simple problems, one or more queues can be enough (Azure Storage Queue)

Almost all messaging system allow us to consume messages using Peek and Lock pattern. This allow us to take a message from the queue, lock it for a specific time, process it and at the end, if we are able to process it with success to remove it from the queue. During this time, the message is hidden from others consumers and cannot be peeked by others. After a specific time interval if we don't mark the message as consumed the message will be available in the queue for consuming.

But what should we do when we have a long running processing task, that can take 20 minutes or 1 hour. The most simple solution would be to split the task in subtasks - when is possible.
This means that we would have multiple sub-components that needs to communicate between each other. We would end up with multiple queues or with an enterprise service bus system like Azure Service Bus Topic.

But what should we do when we cannot split it? Or the complexity of splitting in subtasks is so high that it not worth it... and even if we would be able to split it in subtasks, we would end up with something similar like a 'state machine'. This state would be used to know the current status of the tasks and would allow us to be able to continue from the last step. For this case, it would be nice to be able to update the content of a message that is the queue without having to remove the original message.

For long running tasks this could be very useful. We could update the current progress/status of task in the queue, without having to use a storage for this. This can be done very simple if we are using Azure Storage Queue. This queue system allow us to update an existing message that is the queue. See below code:
CloudQueue queue = queueClient. GetQueueReference("fooqueue");

CloudQueueMessage message = queue.GetMessage(new TimeSpan(0,0,10);
String newMessageContent = message + " new message content";

queue.UpdateMessage(message, MessageUpdateField.Content);
We can use this feature each time when we need to update the progress of a task that was triggered by a message in the queue. Beside the content we can update any other fields of the message (for example the visibility property).

In this post we saw how simple is to update the content of a message from a queue without having to remove and recreate it.


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