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Real-time monitoring system for 300+ university lab PCs. Tracks and displays each computer’s status (FREE, IN_SESSION, OFFLINE) through a Go-based WebSocket gateway and React dashboard.

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Session Service - Real-Time Monitoring System

Real-time monitoring system for 300+ computers across university laboratories.
It allows visualization of the current state of all PCs — FREE, IN_SESSION, or OFFLINE — distributed among different university labs.

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Service (Backend): Go + Gorilla WebSocket + Windows Services API

Frontend: React + TypeScript + Vite + WebSocket API

Table of Contents

Architecture

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System States

  • FREE: PC is powered on and available for use
  • IN_SESSION: PC is currently in use by a user
  • OFFLINE: PC is powered off or not connected

Main Components

  1. Gateway Server (Go): Central WebSocket server that receives heartbeats from agents
  2. Agent Client (Go): Windows service running on each PC
  3. Frontend Dashboard (React): Web interface for real-time status visualization

Computers Network & Sessions

Laboratory Range PC Range IP
B0-Libre Sistemas25 – Sistemas49, Sistemas78 – Sistemas80 10.2.67.25 – 10.2.67.49, 10.2.67.78 – 10.2.67.79, 81
Plataformas Sistemas01 – Sistemas24 10.2.67.1 – 10.2.67.24
Ing-Software Sistemas50 – Sistemas73 10.2.67.50 – 10.2.67.73
Redes Sistemas101 – Sistemas116 10.2.67.101 – 10.2.67.116
Interactiva Interactiva01 – Interactiva08 10.2.67.151 – 10.2.67.158
Multimedia Sistemas160 – Sistemas175 10.2.67.161 – 10.2.67.172, 175
Fundamentos Sistemas176 – Sistemas199 10.2.67.176 – 10.2.67.199
Juegos Sistemas200 – Sistemas217 10.2.67.200 – 10.2.67.218
EDFI Sistemas240, Sistemas301 – Sistemas330, Sistemas343, Sistemas345, Sistemas354, Sistemas389
10.2.68.1 - 30
(Profe 10.2.68.50)

| | NEW Arq-Sistemas | Sistemas351 – Sistemas373 | 10.2.68.51 – 73 |

Componentes

Gateway Server (server.go)

  • Puerto por defecto: :8080
  • Endpoints:
    • GET / - Pagina HTML simple de debug
    • GET /api/devices - API REST con lista de dispositivos
    • WS /ws/agent - WebSocket para conexion de agentes
    • WS /ws/client - WebSocket para dashboards

Agent Client (client.go / client_service.go)

  • Servicio de Windows con auto-inicio
  • Envia heartbeats cada 5 segundos
  • Reconexion automatica con exponential backoff
  • Detecta IP local automaticamente

Frontend Dashboard

  • React + Vite
  • WebSocket para actualizaciones en tiempo real
  • Visualizacion de estado de todos los equipos

Requisitos

Gateway Server

  • Go 1.20+
  • Sistema operativo: Linux/Windows
  • Puerto 8080 abierto en firewall
  • Dependencias: 
    go get github.com/gorilla/websocket

Agent Client

  • Go 1.20+
  • Windows 10/11
  • Privilegios de Administrador (para instalacion)
  • Dependencias: 
    go get github.com/gorilla/websocket
go get golang.org/x/sys/windows/svc
go get golang.org/x/sys/windows/svc/eventlog

Frontend Dashboard

  • Node.js 18+
  • npm o yarn
  • Navegador moderno (Chrome, Firefox, Edge)

Instalacion Rapida

1. Clonar el repositorio

git clone https://github.com/tu-universidad/labinfo.git
cd labinfo

2. Iniciar el Gateway

cd server
go run server.go

El servidor estara disponible en http://localhost:8080

3. Probar un agente localmente

cd client
go run client.go

4. Ver el dashboard

Abre tu navegador en http://localhost:8080

Instalacion del Gateway

Compilar el Gateway

cd server
go build -o labinfo-gateway server.go

Ejecutar como servicio (Windows)

Usar NSSM (Non-Sucking Service Manager):

# Descargar NSSM desde https://nssm.cc/download
nssm install LabInfoGateway "C:\LabInfo\labinfo-gateway.exe"
nssm set LabInfoGateway Description "LabInfo Gateway Server"
nssm set LabInfoGateway Start SERVICE_AUTO_START
nssm start LabInfoGateway

Instalacion del Agente

Metodo 1: Script Automatico (Recomendado)

Paso 1: Compilar el agente

cd client
go build -o labinfo-agent.exe client_service.go

Paso 2: Ejecutar el instalador

# Abrir PowerShell como Administrador
.\install.ps1 -ServerURL "ws://192.168.1.100:8080/ws/agent"

El script automaticamente:

  • Crea directorios necesarios
  • Copia el ejecutable
  • Configura variables de entorno
  • Instala el servicio de Windows
  • Inicia el servicio

Paso 3: Verificar instalacion

Get-Service LabInfoAgent
Get-Content "C:\ProgramData\LabInfo\agent.log" -Tail 20

Metodo 2: Instalacion Manual

# 1. Crear directorios
mkdir "C:\Program Files\LabInfo"
mkdir "C:\ProgramData\LabInfo"

# 2. Copiar ejecutable
Copy-Item labinfo-agent.exe "C:\Program Files\LabInfo\labinfo-agent.exe"

# 3. Configurar URL del servidor
[Environment]::SetEnvironmentVariable("LABINFO_WS", "ws://192.168.1.100:8080/ws/agent", "Machine")

# 4. Crear servicio
sc.exe create LabInfoAgent binPath= "C:\Program Files\LabInfo\labinfo-agent.exe" start= auto DisplayName= "LabInfo Monitoring Agent"

# 5. Iniciar servicio
Start-Service LabInfoAgent

Desinstalar Agente

# Ejecutar script de desinstalacion
C:\Program Files\LabInfo\uninstall.ps1

# O manualmente:
Stop-Service LabInfoAgent
sc.exe delete LabInfoAgent
Remove-Item "C:\Program Files\LabInfo" -Recurse -Force
[Environment]::SetEnvironmentVariable("LABINFO_WS", $null, "Machine")

Configuracion

Variables de Entorno

Gateway Server

  • LABINFO_ADDR - Direccion y puerto del servidor (default: :8080) 
    export LABINFO_ADDR=":9000"

Agent Client

  • LABINFO_WS - URL del WebSocket del gateway (default: ws://localhost:8080/ws/agent) 
    [Environment]::SetEnvironmentVariable("LABINFO_WS", "ws://192.168.1.100:8080/ws/agent", "Machine")

Configuracion del Firewall

Windows Firewall (Gateway Server)

New-NetFirewallRule -DisplayName "LabInfo Gateway" -Direction Inbound -Protocol TCP -LocalPort 8080 -Action Allow

Linux iptables

sudo iptables -A INPUT -p tcp --dport 8080 -j ACCEPT
sudo iptables-save > /etc/iptables/rules.v4

Uso

Comandos Utiles del Gateway

# Ver logs en tiempo real (Linux)
journalctl -u labinfo-gateway -f

# Reiniciar servicio
sudo systemctl restart labinfo-gateway

# Ver estado
sudo systemctl status labinfo-gateway

Comandos Utiles del Agente

# Ver estado del servicio
Get-Service LabInfoAgent

# Ver logs en tiempo real
Get-Content "C:\ProgramData\LabInfo\agent.log" -Wait -Tail 20

# Reiniciar servicio
Restart-Service LabInfoAgent

# Detener servicio
Stop-Service LabInfoAgent

# Iniciar servicio
Start-Service LabInfoAgent

Probar WebSocket Manualmente

# Instalar wscat (si no esta instalado)
npm install -g wscat

# Conectar como agente
wscat -c ws://localhost:8080/ws/agent

# Enviar mensaje de ejemplo:
{"agent_id":"test-pc","ip":"192.168.1.50","state":"FREE","timestamp":"2025-10-17T12:00:00Z"}

# Conectar como dashboard
wscat -c ws://localhost:8080/ws/client

API

REST Endpoints

GET /api/devices

Obtiene la lista de todos los dispositivos conectados.

Response:

[
  {
    "agent_id": "PC-LAB-A-01",
    "ip": "192.168.1.10",
    "lab_id": "LAB-A",
    "state": "FREE",
    "username": "",
    "timestamp": "2025-10-17T15:30:45Z",
    "version": "mvp-0.1"
  },
  {
    "agent_id": "PC-LAB-A-02",
    "ip": "192.168.1.11",
    "state": "IN_SESSION",
    "username": "john.doe",
    "timestamp": "2025-10-17T15:30:46Z"
  }
]

WebSocket Protocol

Agent -> Server (via /ws/agent)

Message Format:

{
  "agent_id": "PC-LAB-A-01",
  "ip": "192.168.1.10",
  "lab_id": "LAB-A",
  "state": "FREE",
  "username": "john.doe",
  "timestamp": "2025-10-17T15:30:45Z",
  "version": "mvp-0.1"
}

Server ACK:

{
  "status": "ok"
}

Server -> Dashboard (via /ws/client)

Initial Snapshot:

{
  "type": "snapshot",
  "devices": [
    {
      "agent_id": "PC-LAB-A-01",
      "ip": "192.168.1.10",
      "state": "FREE",
      "timestamp": "2025-10-17T15:30:45Z"
    }
  ]
}

State Change Event:

{
  "type": "state_change",
  "device": {
    "agent_id": "PC-LAB-A-01",
    "ip": "192.168.1.10",
    "state": "IN_SESSION",
    "username": "john.doe",
    "timestamp": "2025-10-17T15:31:00Z"
  }
}

Despliegue Masivo

Usando Group Policy (GPO) - Dominio Windows

  1. Compila el agente y copia los archivos a un share de red:

    \\servidor\labinfo\labinfo-agent.exe
\\servidor\labinfo\install.ps1

  2. Crea un GPO:

    • Computer Configuration → Policies → Windows Settings → Scripts
    • Startup Scripts → Add → PowerShell Scripts
    • Script Name: \\servidor\labinfo\install.ps1
    • Script Parameters: -ServerURL "ws://192.168.1.100:8080/ws/agent"

  3. Vincula el GPO a las OUs de los laboratorios

  4. Fuerza actualizacion en un PC de prueba:

    gpupdate /force

Usando PSRemoting (Sin GPO)

# Crear archivo con lista de PCs
$computers = Get-Content "equipos.txt"

# Despliegue en paralelo
$computers | ForEach-Object -Parallel {
    $computer = $_
    
    try {
        # Copiar archivos
        Copy-Item "labinfo-agent.exe" "\\$computer\C$\Temp\" -Force
        Copy-Item "install.ps1" "\\$computer\C$\Temp\" -Force
        
        # Ejecutar instalacion remota
        Invoke-Command -ComputerName $computer -ScriptBlock {
            Set-Location C:\Temp
            .\install.ps1 -ServerURL "ws://192.168.1.100:8080/ws/agent"
        }
        
        Write-Host "OK: $computer" -ForegroundColor Green
    }
    catch {
        Write-Host "ERROR: $computer - $_" -ForegroundColor Red
    }
} -ThrottleLimit 10

Usando SCCM / Intune

  1. Crea un paquete de aplicacion con:

    • labinfo-agent.exe
    • Script de instalacion personalizado

  2. Configura deteccion:

    • Registry: HKLM\SYSTEM\CurrentControlSet\Services\LabInfoAgent
    • O File: C:\Program Files\LabInfo\labinfo-agent.exe

  3. Despliega a las colecciones de dispositivos de laboratorios

Troubleshooting

Agente no se conecta al Gateway

Sintoma: El agente muestra errores de conexion en los logs.

Solucion:

  1. Verificar conectividad de red:

    Test-NetConnection -ComputerName 192.168.1.100 -Port 8080

  2. Verificar URL configurada:

    [Environment]::GetEnvironmentVariable("LABINFO_WS", "Machine")

  3. Verificar firewall:

    Get-NetFirewallRule | Where-Object {$_.DisplayName -like "*8080*"}

  4. Ver logs del agente:

    Get-Content "C:\ProgramData\LabInfo\agent.log" -Tail 50

Dashboard no recibe actualizaciones

Sintoma: El dashboard muestra datos obsoletos o vacios.

Solucion:

  1. Verificar que el servidor esta corriendo:

    curl http://192.168.1.100:8080/api/devices

  2. Abrir DevTools en el navegador:

    • Network → WS → Verificar conexion WebSocket
    • Console → Ver errores JavaScript

  3. Verificar logs del servidor:

    # Buscar "dashboard client connected"
journalctl -u labinfo-gateway | grep "dashboard client"

  4. Probar conexion manual:

    wscat -c ws://192.168.1.100:8080/ws/client

Servicio no inicia automaticamente

Sintoma: Despues de reiniciar el PC, el servicio no esta corriendo.

Solucion:

  1. Verificar configuracion de inicio:

    Get-Service LabInfoAgent | Select-Object Name, Status, StartType

  2. Debe mostrar StartType: Automatic

  3. Si no, configurar:

    Set-Service -Name LabInfoAgent -StartupType Automatic

  4. Ver eventos del sistema:

    Get-EventLog -LogName System | Where-Object {$_.Source -eq "Service Control Manager" -and $_.Message -like "*LabInfo*"}

Alto uso de CPU/Memoria

Sintoma: El Gateway consume muchos recursos.

Causa: 400 agentes × 80 msg/s → broadcast a multiples dashboards.

Soluciones:

  1. Implementar rate limiting en broadcast
  2. Agregar compresion WebSocket
  3. Solo enviar cambios reales (no heartbeats sin cambio)
  4. Implementar Redis para estado compartido

Logs no se generan

Sintoma: Archivo agent.log vacio o inexistente.

Solucion:

  1. Verificar permisos en el directorio:

    icacls "C:\ProgramData\LabInfo"

  2. Ejecutar servicio con permisos de sistema:

    sc.exe config LabInfoAgent obj= LocalSystem

  3. Verificar que el directorio existe:

    Test-Path "C:\ProgramData\LabInfo"

Roadmap

Current Version (v1.0 - Production Ready) ✅

  • WebSocket Gateway in Go
  • Windows Agent as a service
  • Basic React Dashboard
  • States: FREE, IN_SESSION, OFFLINE
  • Auto-reconnection with exponential backoff
  • Automated installation script
  • Thread-safe operations (no race conditions)
  • Consistent state sync (snapshots, not accumulation)
  • Unique client identification (by IP + hostname)
  • Automated testing (race detection scripts)

Version 1.0 (Production)

  • Persistence: Redis for current state + PostgreSQL for history
  • Authentication: JWT or OAuth2 for the dashboard
  • Metrics: Prometheus + Grafana
  • Intelligent state detection (via WMI queries)
  • Automatic Lab ID (detect by IP range or config)
  • Notifications: Alerts when labs are full/empty
  • Extended API: Filters by lab, statistics, reports

Latest Fixes (v1.0 - Oct 2025) 🔧

Critical Issues Resolved:

  • ✅ Race Condition Fix: Eliminated concurrent map writes panics in server
  • ✅ State Accumulation Fix: Frontend no longer accumulates counters (1 client = 1 display, not N)
  • ✅ Unique Identification: Added agent_id and ip to broadcasts for proper client tracking
  • ✅ Thread-Safe Broadcast: Atomic region with single lock/unlock in broadcastUpdate()
  • ✅ Snapshot-Based Updates: Dashboard receives full snapshots (not incremental changes)
  • ✅ Auto-Recovery: State drift auto-corrects on next snapshot

Documentation Added:

  • 📄 RACE_CONDITION_FIX.md - Technical deep-dive
  • 📄 EXECUTIVE_SUMMARY.md - High-level overview
  • 📄 QUICK_VERIFICATION.md - Testing guide
  • 🧪 test_race_conditions.ps1/sh - Automated test scripts

Before: 1 client changing state 10 times = frontend shows 10 clients ❌
After: 1 client changing state 100 times = frontend shows 1 client ✅

See RACE_CONDITION_FIX.md for detailed technical analysis.

Version 1.1 (Next Release)

  • Persistence: Redis for current state + PostgreSQL for history

  • Authentication: JWT or OAuth2 for the dashboard

  • Metrics: Prometheus + Grafana

  • Intelligent state detection (via WMI queries)

  • Automatic Lab ID (detect by IP range or config)

  • Notifications: Alerts when labs are full/empty

  • High Availability: Multiple gateway instances with Redis Pub/Sub

  • Machine Learning: Lab usage prediction

  • Mobile App: Native iOS/Android

  • SSO Integration: LDAP/Active Directory

  • Advanced Dashboard: Lab maps, reservations, heatmaps

  • Webhooks: Integration with external systems

License

Apache License 2.0 – See the LICENCE file for details.

Contact

Credits

Team: Sergio Silva & Tulio Riaño

© 2025 Computer Lab, Escuela Colombiana de Ingeniería Julio Garavito.
All rights reserved.

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Real-time monitoring system for 300+ university lab PCs. Tracks and displays each computer’s status (FREE, IN_SESSION, OFFLINE) through a Go-based WebSocket gateway and React dashboard.

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