Message Queue

You might say

Don't make the user stare at a spinner while generating this huge report. Put the job into a message queue and let background workers process it.

A communication and decoupling mechanism that temporarily stores messages between senders and receivers so neither must wait synchronously.When a user exports a large report, the API creates a job, writes its ID and parameters to a queue, and immediately returns a pending status. A worker generates the file and updates the same ID to completed or failed. Enqueueing proves receipt, not completion, and retries can cause the same job to be delivered again.

Know first

API Serverless Transaction

MQMessage Broker

How message queues buffer and distribute tasks reliably

Report export jobStage 1 · Synchronous work causes waiting

Task ID: not created

Export pageClicks “Export invoices”

Message queueNot used

File generationRuns inside the request

UI stateKeeps waiting and may time out

EvidenceThe request remains open during generation, with no task ID the page can check later

Long-running work is tied to the page request; after an interruption, task state is unclear.

How one report export moves through a message queue

Before: the page waits for all background work: After the user clicks Export, one request queries data, builds the file, and uploads it. A slow step can leave the page spinning or time out, and the user has no durable task status to check later.

Enqueue the work and return status through one task ID: The API creates export_104, enqueues its parameters and ID, and returns that ID. A worker marks the same task processing, then stores either a file location or readable failure. The page shows queued, processing, completed, or failed under that ID. Enqueued means accepted, not completed.

Verify evidence across the whole path: Match export_104 across the API response, queued message, worker log, and final UI state. Retry a failed task and confirm duplicate delivery does not create two files. A single 'message enqueued' log does not prove completion.

You can say this to an AI Agent

This Excel export blocks the request too long. Make it asynchronous: create and enqueue a job, return its ID immediately, and have the worker update queued, processing, completed, or failed under the same ID. Make duplicate delivery safe, then verify both a successful export and a worker failure.

Learn next

1Enqueue→2Message Consumer→3Idempotency→

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After paying for an order, SMS confirmation and invoicing are needed. What is the primary benefit of using a message queue?

A. The checkout API must block until the queue confirms that both SMS delivery and invoice generation have succeededB. Once a task enters the message queue, the SMS is considered delivered without requiring any worker to process itC. After payment completes, the API enqueues SMS and invoicing tasks, returns the order result, and lets workers process them