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v0.3.0, persistent polling update.

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2026-02-17 02:56:11 +00:00
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README.md
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@@ -1,6 +1,6 @@
# SLMM - Sound Level Meter Manager
**Version 0.2.1**
**Version 0.3.0**
Backend API service for controlling and monitoring Rion NL-43/NL-53 Sound Level Meters via TCP and FTP protocols.
@@ -12,8 +12,9 @@ SLMM is a standalone backend module that provides REST API routing and command t
## Features
- **Background Polling** ⭐ NEW: Continuous automatic polling of devices with configurable intervals
- **Offline Detection** ⭐ NEW: Automatic device reachability tracking with failure counters
- **Persistent TCP Connections**: Cached per-device connections with OS-level keepalive, tuned for cellular modem reliability
- **Background Polling**: Continuous automatic polling of devices with configurable intervals
- **Offline Detection**: Automatic device reachability tracking with failure counters
- **Device Management**: Configure and manage multiple NL43/NL53 devices
- **Real-time Monitoring**: Stream live measurement data via WebSocket
- **Measurement Control**: Start, stop, pause, resume, and reset measurements
@@ -22,6 +23,7 @@ SLMM is a standalone backend module that provides REST API routing and command t
- **Device Configuration**: Manage frequency/time weighting, clock sync, and more
- **Rate Limiting**: Automatic 1-second delay enforcement between device commands
- **Persistent Storage**: SQLite database for device configs and measurement cache
- **Connection Diagnostics**: Live UI and API endpoints for monitoring TCP connection pool status
## Architecture
@@ -29,29 +31,39 @@ SLMM is a standalone backend module that provides REST API routing and command t
┌─────────────────┐ ┌──────────────────────────────┐ ┌─────────────────┐
│ │◄───────►│ SLMM API │◄───────►│ NL43/NL53 │
│ (Frontend) │ HTTP │ • REST Endpoints │ TCP │ Sound Meters │
└─────────────────┘ │ • WebSocket Streaming │ └─────────────────┘
│ • Background Poller ⭐ NEW │ ▲
└──────────────────────────────┘ │
│ Continuous
▼ Polling
┌──────────────┐ │
│ SQLite DB │◄─────────────────────┘
└─────────────────┘ │ • WebSocket Streaming │ (kept │ (via cellular │
│ • Background Poller │ alive) │ modem) │
│ • Connection Pool (v0.3) │ └─────────────────┘
└──────────────────────────────┘
│
▼
┌──────────────┐
│ SQLite DB │
│ • Config │
│ • Status │
└──────────────┘
```
### Persistent TCP Connection Pool (v0.3.0)
SLMM maintains persistent TCP connections to devices with OS-level keepalive, designed for reliable operation over cellular modems:
- **Connection Reuse**: One cached TCP socket per device, reused across all commands (no repeated handshakes)
- **TCP Keepalive**: Probes keep cellular NAT tables alive and detect dead connections early
- **Transparent Retry**: Stale cached connections automatically retry with a fresh socket
- **Configurable**: Idle TTL (300s), max age (1800s), and keepalive timing via environment variables
- **Diagnostics**: Live UI on the roster page and API endpoints for monitoring pool status
### Background Polling (v0.2.0)
SLMM now includes a background polling service that continuously queries devices and updates the status cache:
Background polling service continuously queries devices and updates the status cache:
- **Automatic Updates**: Devices are polled at configurable intervals (10-3600 seconds)
- **Offline Detection**: Devices marked unreachable after 3 consecutive failures
- **Per-Device Configuration**: Each device can have a custom polling interval
- **Resource Efficient**: Dynamic sleep intervals and smart scheduling
- **Graceful Shutdown**: Background task stops cleanly on service shutdown
This makes Terra-View significantly more responsive - status requests return cached data instantly (<100ms) instead of waiting for device queries (1-2 seconds).
Status requests return cached data instantly (<100ms) instead of waiting for device queries (1-2 seconds).
## Quick Start
@@ -96,9 +108,18 @@ Once running, visit:
### Environment Variables
**Server:**
- `PORT`: Server port (default: 8100)
- `CORS_ORIGINS`: Comma-separated list of allowed origins (default: "*")
**TCP Connection Pool:**
- `TCP_PERSISTENT_ENABLED`: Enable persistent connections (default: "true")
- `TCP_IDLE_TTL`: Close idle connections after N seconds (default: 300)
- `TCP_MAX_AGE`: Force reconnect after N seconds (default: 1800)
- `TCP_KEEPALIVE_IDLE`: Seconds idle before keepalive probes (default: 15)
- `TCP_KEEPALIVE_INTERVAL`: Seconds between keepalive probes (default: 10)
- `TCP_KEEPALIVE_COUNT`: Failed probes before declaring dead (default: 3)
### Database
The SQLite database is automatically created at [data/slmm.db](data/slmm.db) on first run.
@@ -126,7 +147,7 @@ Logs are written to:
| GET | `/api/nl43/{unit_id}/live` | Request fresh DOD data from device (bypasses cache) |
| WS | `/api/nl43/{unit_id}/stream` | WebSocket stream for real-time DRD data |
### Background Polling Configuration ⭐ NEW
### Background Polling
| Method | Endpoint | Description |
|--------|----------|-------------|
@@ -134,6 +155,13 @@ Logs are written to:
| PUT | `/api/nl43/{unit_id}/polling/config` | Update polling interval and enable/disable polling |
| GET | `/api/nl43/_polling/status` | Get global polling status for all devices |
### Connection Pool
| Method | Endpoint | Description |
|--------|----------|-------------|
| GET | `/api/nl43/_connections/status` | Get pool config, active connections, age/idle times |
| POST | `/api/nl43/_connections/flush` | Force-close all cached TCP connections |
### Measurement Control
| Method | Endpoint | Description |
@@ -255,6 +283,9 @@ Caches latest measurement snapshot:
### TCP Communication
- Uses ASCII command protocol over TCP
- Persistent connections with OS-level keepalive (tuned for cellular modems)
- Connections cached per device and reused across commands
- Transparent retry on stale connections
- Enforces ≥1 second delay between commands to same device
- Two-line response format:
- Line 1: Result code (R+0000 for success)
@@ -320,6 +351,16 @@ curl http://localhost:8100/api/nl43/meter-001/polling/config
curl http://localhost:8100/api/nl43/_polling/status
```
### Check Connection Pool Status
```bash
curl http://localhost:8100/api/nl43/_connections/status | jq '.'
```
### Flush All Cached Connections
```bash
curl -X POST http://localhost:8100/api/nl43/_connections/flush
```
### Verify Device Settings
```bash
curl http://localhost:8100/api/nl43/meter-001/settings
@@ -388,11 +429,19 @@ See [API.md](API.md) for detailed integration examples.
## Troubleshooting
### Connection Issues
- Check connection pool status: `curl http://localhost:8100/api/nl43/_connections/status`
- Flush stale connections: `curl -X POST http://localhost:8100/api/nl43/_connections/flush`
- Verify device IP address and port in configuration
- Ensure device is on the same network
- Check firewall rules allow TCP/FTP connections
- Verify RX55 network adapter is properly configured on device
### Cellular Modem Issues
- If modem wedges from too many handshakes, ensure `TCP_PERSISTENT_ENABLED=true` (default)
- Increase `TCP_IDLE_TTL` if connections expire between poll cycles
- Keepalive probes (default: every 15s) keep NAT tables alive — adjust `TCP_KEEPALIVE_IDLE` if needed
- Set `TCP_PERSISTENT_ENABLED=false` to disable pooling for debugging
### Rate Limiting
- API automatically enforces 1-second delay between commands
- If experiencing delays, this is normal device behavior