Nicht-funktionale Anforderungen

Audience: Dev, Ops
You will learn: - Performance-Ziele und -Messungen für das Icon-Tool - Verfügbarkeits- und Skalierungsanforderungen - Sicherheits- und Compliance-Anforderungen - Privacy- und Datenschutz-Überlegungen

Pre-requisites: - Architektur-Übersicht verstanden - Grundverständnis von NFRs und SLAs

Performance

Response Time Requirements

Endpoint	Target	Maximum	Measurement
GET /	<100ms	200ms	Time to first byte
GET /api/icons	<50ms	100ms	JSON response time
GET /static/icons/*.svg	<10ms	50ms	Static file delivery
Icon Extraction	<3s	5s	Full extraction time

Throughput Requirements

Operation	Target	Notes
Concurrent Users	20+	Typical development team size
API Requests/sec	100+	Burst capacity für CI/CD
Icon Downloads	50+ parallel	ZIP download stress test

Resource Usage

Resource	Development	Production	Limit
Memory (Flask)	30MB	50MB	100MB
Disk (Icons)	2MB	5MB	10MB
CPU (Extraction)	<50%	<80%	Single core

Monitoring:

# Response Time Measurement
curl -w "@curl-format.txt" -o /dev/null http://localhost:5000/api/icons

# Memory Usage
ps aux | grep "python app.py" | awk '{print $6}'

# Disk Usage
du -sh static/icons/

Evidence: app.py performance characteristics, replit.md:89

Performance Optimization

1. Static File Caching

# Flask-Cache für statische Icon-Metadaten
@app.route('/api/icons')
@cache.cached(timeout=300)  # 5 Minuten Cache
def api_icons():
    # ...

2. File System Optimization

# Icons in Memory laden (für <200 Icons)
# Siehe: app.py load_icon_categories()

3. ZIP-Kompression

• Level 9 Compression: Maximale Größenreduktion
• Target: <70KB für 162 Icons
• Current: 69KB (replit.md:89)

Evidence: create-selected-icons.js:52, archiver configuration

Availability

Uptime Requirements

Component	Target	Acceptable Downtime
Web Interface	99.0%	3.6 days/year
Icon Extraction	On-demand	Build-tool, nicht kritisch
File Serving	99.9%	8.7 hours/year

Fault Tolerance

1. Graceful Degradation

# Fallback bei fehlenden Metadaten
def get_icon_list():
    try:
        categories = load_icon_categories()
    except FileNotFoundError:
        categories = {}  # Graceful fallback
        app.logger.warning("icons.json not found, using empty categories")

2. Health Checks

@app.route('/health')
def health_check():
    checks = {
        'icons_directory': os.path.exists('static/icons'),
        'metadata_file': os.path.exists('icons.json'),
        'icon_count': len(os.listdir('static/icons'))
    }

    if all(checks.values()):
        return jsonify({'status': 'healthy', 'checks': checks})
    else:
        return jsonify({'status': 'unhealthy', 'checks': checks}), 503

3. Recovery Procedures

# Automatische Wiederherstellung bei Problemen
if [ ! -d "static/icons" ] || [ $(ls static/icons | wc -l) -lt 150 ]; then
    echo "Icon directory corrupted, regenerating..."
    node extract-icons.js
fi

Evidence: app.py:15-43 error handling

Scalability

Horizontal Scaling Limits

Component	Current Limit	Scale-out Strategy
Flask App	1 instance	Load balancer + shared storage
Icon Storage	1 file system	NFS/S3 für shared storage
Metadata	1 JSON file	Database migration bei >500 Icons

Vertical Scaling

Resource	Current	2x Load	10x Load
Memory	30MB	50MB	200MB
CPU	<10%	20%	80%
Disk I/O	Minimal	Low	Medium

Performance Bottlenecks

1. File System Directory Scanning

# Potential bottleneck bei >1000 Icons
icons = os.listdir('static/icons')

# Solution: Caching oder Database-Migration

2. JSON Metadata Loading

# icons.json wird bei jedem Request geladen
# Solution: In-Memory-Caching

Evidence: app.py:31-43 directory scanning logic

Security

Threat Model

Threat	Likelihood	Impact	Mitigation
Path Traversal	Low	Medium	Input validation
DoS (Large Requests)	Medium	Low	Rate limiting
Dependency Vulnerabilities	Medium	Medium	Regular updates

Security Controls

1. Input Validation

# Secure file serving
@app.route('/icon/<icon_name>')
def get_icon(icon_name):
    # Validate icon name gegen directory listing
    valid_icons = [f[:-4] for f in os.listdir('static/icons') if f.endswith('.svg')]
    if icon_name not in valid_icons:
        return jsonify({'error': 'Icon not found'}), 404

2. Dependency Security

# Regular security audits
npm audit
pip-audit  # für Python dependencies

# Expected: No high/critical vulnerabilities

3. Static File Security

• Content-Type Headers: Explicit SVG MIME-type
• No User Uploads: Nur administrative Icon-Updates
• Read-Only Access: Web-App hat keine Write-Permissions

Evidence: app.py:57-64 input validation

Compliance

Open Source Licenses

• FontAwesome Free: SIL OFL 1.1, MIT, CC BY 4.0
• Compliance: Attribution requirements erfüllt
• Distribution: Lizenz-kompatible Weitergabe

Data Protection

• No Personal Data: Keine Benutzer-Registrierung oder -Tracking
• No Cookies: Stateless Interface
• No Logging: Keine IP-Adressen oder User-Agents

Evidence: docs/README.md:136, FontAwesome license terms

Privacy

Data Minimization

• No User Accounts: Anonyme Nutzung
• No Analytics: Keine Tracking-Pixel oder Scripts
• No Server Logs: Standard-Access-Logs only (IP-Anonymisierung möglich)

GDPR Compliance

• Legal Basis: Legitimate interest für Icon-Bereitstellung
• Data Subject Rights: Nicht anwendbar (keine personenbezogenen Daten)
• Privacy by Design: Architektur ohne Datensammlung

Monitoring & Observability

Key Performance Indicators

# Monitoring-Endpunkt
@app.route('/metrics')
def metrics():
    return jsonify({
        'icon_count': len(os.listdir('static/icons')),
        'categories': len(load_icon_categories()),
        'uptime': time.time() - start_time,
        'memory_usage': psutil.Process().memory_info().rss
    })

Alerting Thresholds

Metric	Warning	Critical
Response Time	>200ms	>500ms
Memory Usage	>80MB	>150MB
Icon Count	<150	<100
Error Rate	>1%	>5%

Log Analysis

# Error Pattern Detection
grep "ERROR" flask.log | tail -100

# Performance Analysis
grep "slow response" flask.log

Disaster Recovery

Backup Strategy

• Repository: Git-basiertes Backup aller Source-Files
• Generated Icons: Können jederzeit aus extract-icons.js regeneriert werden
• No Data Loss Risk: Stateless system ohne persistente User-Daten

Recovery Time Objectives

• RTO (Recovery Time): <5 Minuten (Git clone + dependency install)
• RPO (Data Loss): 0 (alle Daten in Git)

Recovery Procedures

# Vollständige Systemwiederherstellung
git clone <repository>
npm install
pip install flask
node extract-icons.js
python app.py

Evidence: Replit deployment architecture, Git repository structure

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SLA Summary: - Availability: 99.0% (development tool, nicht business-critical) - Performance: <100ms API responses, <3s icon extraction
- Security: Input validation, dependency audits, secure defaults - Privacy: No personal data collection, GDPR-compliant by design

Next Review: Bei Architektur-Änderungen oder Performance-Problemen