EngineerExperiences

Part 6 of 12 ESP32C++ReactInfluxDBGrafana

C++20 oatpp Backend Service

The Pulzaura backend is written in modern C++20 using the zero-dependency oatpp 1.4.0 framework to guarantee deterministic low-latency processing of biosignal telemetry.

BLE Hardware Acquisition via BlueZ & D-Bus

Instead of third-party wrapper runtimes, the backend interfaces directly with Linux’s kernel Bluetooth daemon via D-Bus:

  • Uses GLib main loop and D-Bus IPC to inspect Bluetooth adapters.
  • Auto-discovers and connects to the wearable device advertising the Pulzaura UUID.
  • Registers for notifications on characteristic 0000f00d-0000-1000-8000-00805f9b34fb.

Concurrency & Thread Isolation

Backend thread isolation from BLE acquisition to WebSocket broadcast and InfluxDB writes BLE / BlueZ thread Raw packet unpack notify frames Ring buffer queue InfluxWriter queue WebSocket broadcast thread, 50–100 Hz to clients InfluxDB writer thread, HTTP line protocol
Each queue has its own thread, so a slow database write can never stall the live dashboard.
  • Ring Buffer: Locks are avoided using lock-free ring buffers between network acquisition and WebSocket broadcasters.
  • WebSocket Serialization: Converts parsed 9-channel floats into compact JSON frames streamed to connected browser clients at 50–100 Hz.