IClientSubscribeOptions

Kind: Interface

Source: packages/microservices/external/mqtt-options.interface.ts

Part of: Microservices

IClientSubscribeOptions defines configuration for MQTT topic subscriptions in the microservices transport layer. It currently specifies the Quality of Service (qos) level used when subscribing, controlling message delivery guarantees between the MQTT broker and client.

Properties

Diagram

mermaid
graph LR
  Client[MQTT Client] -->|subscribe(topic, options)| Options[IClientSubscribeOptions]
  Options -->|qos| QoS[MQTT QoS Level]
  Client --> Broker[MQTT Broker]
  Broker -->|messages with delivery guarantee| Client

Usage

ts
import { QoS } from 'mqtt-packet';
import type { IClientSubscribeOptions } from './mqtt-options.interface';

const subscribeOptions: IClientSubscribeOptions = {
  qos: QoS.AtLeastOnce,
};

mqttClient.subscribe('devices/+/status', subscribeOptions, (error) => {
  if (error) {
    console.error('Unable to subscribe to device status updates', error);
  }
});

AI Coding Instructions

• Provide a valid MQTT QoS enum value for qos; do not use arbitrary numeric values unless supported by the MQTT client dependency.
• Match the subscription QoS level to delivery requirements: lower levels favor performance, while higher levels provide stronger delivery guarantees.
• Pass this interface as the options object when integrating with MQTT client subscribe() calls.
• Keep subscription options transport-specific; avoid reusing MQTT QoS settings for non-MQTT microservice transports.