Workers

Workers are internal background processes that consume Kafka events produced by the platform's microservices. They have no public REST API — each exposes only GET /status (health check) and GET /metrics (Prometheus).

Overview

Worker Summary

Worker	Port	Role
Dispatcher	4010	Routes MongoDB change events to client webhooks via BullMQ retry queues
Observer	4020	Aggregates create/update/delete statistics into special/stats
Preserver	4030	EMQX ExHook gRPC server — handles MQTT auth and session lifecycle
Watcher	4040	Syncs critical entities from MongoDB change events into Redis cache
Publisher	4050	Publishes MQTT messages to EMQX for entity owner/share/client topics
Logger	4060	Persists audit log entries from Kafka to PostgreSQL
Cleaner	4070	Purges expired records from MongoDB, PostgreSQL, and Redis

Internal Structure

Most workers share this layout:

apps/workers/<name>/src/
├── main.ts              # HTTP health server + Kafka consumer bootstrap
├── app.module.ts        # Root module — DB connections, BullMQ, Kafka clients
├── app.controller.ts    # HTTP: /status, /metrics
├── app.service.ts       # Core business logic invoked by processor/controller
├── app.processor.ts     # @Process() — BullMQ job handler (dispatcher only)
├── app.task.ts          # @Timeout()/@Cron() — scheduled tasks
└── modules/
    └── <domain>/
        └── <entity>/    # Domain-scoped sub-modules

Health Check

Every worker exposes /status:

curl http://localhost:4010/status    # dispatcher
curl http://localhost:4020/status    # observer
curl http://localhost:4030/status    # preserver
curl http://localhost:4040/status    # watcher
curl http://localhost:4050/status    # publisher
curl http://localhost:4060/status    # logger
curl http://localhost:4070/status    # cleaner

Possible dependencies reported: redis, mongo, pgsql, kafka.