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Queue Processing¶

This recipe shows real queue-triggered background processing with queue output bindings, host defaults, and poison queue behavior in Node.js v4.

Architecture¶

flowchart LR
    PRODUCER["HTTP/API Producer"] --> INQ[orders Queue]
    INQ --> WORKER[storageQueue Trigger]
    WORKER --> RESULT[processed-orders Queue Output]
    WORKER --> FAIL[orders-poison after retries]

Prerequisites¶

Create queues:

az storage queue create \
  --account-name $STORAGE_NAME \
  --name orders

az storage queue create \
  --account-name $STORAGE_NAME \
  --name processed-orders

Queue listener defaults in host.json:

{
  "version": "2.0",
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle",
    "version": "[4.*, 5.0.0)"
  },
  "extensions": {
    "queues": {
      "maxPollingInterval": "00:01:00",
      "visibilityTimeout": "00:00:00"
    }
  }
}

Working Node.js v4 Code¶

const { app, output } = require("@azure/functions");

const processedOrdersOutput = output.storageQueue({
  queueName: "processed-orders",
  connection: "AzureWebJobsStorage"
});

app.storageQueue("processOrder", {
  queueName: "orders",
  connection: "AzureWebJobsStorage",
  extraOutputs: [processedOrdersOutput],
  handler: async (queueItem, context) => {
    if (!queueItem.orderId || !queueItem.customerId) {
      throw new Error("Invalid message: orderId and customerId are required.");
    }

    const processed = {
      orderId: queueItem.orderId,
      customerId: queueItem.customerId,
      status: "Processed",
      processedUtc: new Date().toISOString()
    };

    context.extraOutputs.set(processedOrdersOutput, processed);
    context.log("Order processed", { orderId: queueItem.orderId });
  }
});

When the handler keeps failing for the same message, Azure Functions moves the message to orders-poison after the configured maxDequeueCount.

Implementation Notes¶

Use queue triggers for at-least-once asynchronous work and design handlers to be idempotent.
Keep message contracts small and explicit (orderId, customerId) to reduce downstream ambiguity.
Throw errors for non-recoverable malformed payloads so poison queue triage is clear.
Monitor both primary queue depth and *-poison queue depth to catch retry storms early.

See Also¶

Sources¶