cad-function-queue-trigger

Use Azure Functions Core Tools: run `func init` with `--worker-runtime dotnet-isolated --target-framework net8.0`, then `func new --template "Queue trigger"`. Add a `[QueueTrigger("queue-name", Connection = "StorageConnection")]` attribute to the function method parameter.

Start Azurite, set `AzureWebJobsStorage` and your connection setting to `UseDevelopmentStorage=true` in `local.settings.json`, then run `func start`. Create the queue and push test messages with `az storage message put` using the same development storage connection string.

A trigger tells the runtime when to invoke the function, such as a new queue message. A binding moves data, like a Blob input binding that opens a stream or a Blob output binding that writes the return value to storage.

The most common cause is message encoding mismatch: the Azure SDK defaults to no encoding while the Functions runtime expects base64. Set `MessageEncoding = QueueMessageEncoding.Base64` on the producer's QueueClientOptions.

After `maxDequeueCount` failed attempts (default 5), Storage Queue moves the message to a `<queue-name>-poison` queue. Nothing monitors it by default, so you should add a separate function triggered on the poison queue to log or alert on failures.

Use Service Bus when you need transactional workflows, sessions, dead-letter management, or topics and subscriptions. Storage Queues are simpler and cheaper for basic fire-and-forget background processing with at-least-once delivery.