--- title: "Besked K\x0f8" image: /images/user-guide/emails/emails_header.png --- Header Køer muliggør asynkrone operationer. De kan bruges til at udf�0F8re baggrundsopgaver, som for eksempel at sende en velkomstmail ved registrering. Hver anvendelsestilf�0E6lde vil have sin egen k�0F8klasse, der udvides fra `MessageQueueServiceBase`. I �F8jeblikket st�0Ftter vi kun `bull-mq`[bull-mq](https://bullmq.io/) som k�0F�1F er-driver. ## Trin til at oprette og bruge en ny kø 1. Tilf�0Fj et k�0F�F8navn til din nye k�0F�F8 under enum `MESSAGE_QUEUES`. 2. Provide the factory implementation of the queue with the queue name as the dependency token. 3. Inject the queue that you created in the required module/service with the queue name as the dependency token. 4. Add worker class with token based injection just like producer. ### Eksempel p�0E5 anvendelse ```ts class Resolver { constructor(@Inject(MESSAGE_QUEUES.custom) private queue: MessageQueueService) {} async onSomeAction() { //business logic await this.queue.add(someData); } } //async worker class CustomWorker { constructor(@Inject(MESSAGE_QUEUES.custom) private queue: MessageQueueService) { this.initWorker(); } async initWorker() { await this.queue.work(async ({ id, data }) => { //worker logic }); } } ```