Conditional Formatting

Conditional Formatting and Data-Driven Diagrams

Custom Properties with Object Tags

Wrap mxCell in an <object> tag to attach arbitrary key-value metadata to any diagram element:

<object label="Service A" id="2"
        service-id="svc-api-gateway"
        status="healthy"
        latency="45ms"
        uptime="99.97%"
        owner="platform-team"
        environment="production"
        region="us-east-1">
  <mxCell style="rounded=1;whiteSpace=wrap;html=1;fillColor=#d5e8d4;strokeColor=#82b366;"
          vertex="1" parent="1">
    <mxGeometry x="100" y="100" width="120" height="60" as="geometry"/>
  </mxCell>
</object>

Key points:

• label replaces value as the display text
• id moves from mxCell to <object>
• Any attribute name is valid (use lowercase with hyphens)
• Properties are visible in draw.io's Edit Data dialog (Ctrl+M)
• Properties are searchable via Edit > Find/Replace

Placeholder Variables

Display property values dynamically inside labels using %property% syntax. Enable with placeholders=1 in the style:

<object label="%name%&lt;br&gt;Status: %status%&lt;br&gt;Latency: %latency%"
        id="3" placeholders="1"
        name="API Gateway"
        status="healthy"
        latency="42ms">
  <mxCell style="rounded=1;whiteSpace=wrap;html=1;placeholders=1;fillColor=#dae8fc;strokeColor=#6c8ebf;"
          vertex="1" parent="1">
    <mxGeometry x="100" y="100" width="160" height="80" as="geometry"/>
  </mxCell>
</object>

Rendered label:

API Gateway
Status: healthy
Latency: 42ms

Built-in Placeholders

File-Level Variables

Set global variables at the <mxfile> level, accessible by all cells:

<mxfile vars='{"env":"production","version":"2.1.0","region":"us-east-1","last_updated":"2026-03-14"}'>
  <diagram id="page1" name="Status Dashboard">
    <mxGraphModel>
      <root>
        <mxCell id="0"/>
        <mxCell id="1" parent="0"/>
        <object label="Environment: %env%&lt;br&gt;Version: %version%&lt;br&gt;Region: %region%"
                id="header" placeholders="1">
          <mxCell style="text;fontSize=14;fontStyle=1;placeholders=1;" vertex="1" parent="1">
            <mxGeometry x="20" y="20" width="300" height="60" as="geometry"/>
          </mxCell>
        </object>
      </root>
    </mxGraphModel>
  </diagram>
</mxfile>

File-level variables are inherited by all cells that use placeholders=1 and do not have a local property with the same name.

Conditional Formatting Rules

Status to Color Mapping

The most common pattern: map a property value to fill/stroke colors.

Threshold-Based Color Gradients

Map numeric values to colors using thresholds:

Boolean Visibility

Show or hide elements based on boolean properties:

Enumeration to Shape/Icon

Map state values to different visual representations:

Python Update Script

Full-featured script that reads a data source and updates diagram XML:

#!/usr/bin/env python3
"""
update_diagram.py - Update draw.io diagram with live data.

Usage:
    python update_diagram.py --input arch.drawio --output arch-live.drawio --data-url https://api.example.com/health
    python update_diagram.py --input arch.drawio --output arch-live.drawio --data-file status.json
"""

import xml.etree.ElementTree as ET
import json
import argparse
import re
import sys
import urllib.request
import urllib.error
import base64
import zlib
from datetime import datetime, timezone


# Status-to-color mapping
STATUS_COLORS = {
    'healthy':     {'fill': '#D5E8D4', 'stroke': '#82B366'},
    'up':          {'fill': '#D5E8D4', 'stroke': '#82B366'},
    'ok':          {'fill': '#D5E8D4', 'stroke': '#82B366'},
    'warning':     {'fill': '#FFF2CC', 'stroke': '#D6B656'},
    'degraded':    {'fill': '#FFF2CC', 'stroke': '#D6B656'},
    'critical':    {'fill': '#F8CECC', 'stroke': '#B85450'},
    'down':        {'fill': '#F8CECC', 'stroke': '#B85450'},
    'error':       {'fill': '#F8CECC', 'stroke': '#B85450'},
    'maintenance': {'fill': '#E1D5E7', 'stroke': '#9673A6'},
    'unknown':     {'fill': '#F5F5F5', 'stroke': '#666666'},
}


def update_style_property(style: str, key: str, value: str) -> str:
    """Update a single property in a draw.io style string."""
    pattern = re.compile(rf'{re.escape(key)}=[^;]*')
    if pattern.search(style):
        style = pattern.sub(f'{key}={value}', style)
    else:
        if not style.endswith(';'):
            style += ';'
        style += f'{key}={value};'
    return style


def get_threshold_color(value: float, thresholds: list) -> dict:
    """
    Determine color based on value thresholds.
    thresholds: list of (max_value, colors_dict) sorted ascending.
    Example: [(100, green), (500, yellow), (float('inf'), red)]
    """
    for threshold, colors in thresholds:
        if value <= threshold:
            return colors
    return thresholds[-1][1]  # fallback to last


def decompress_diagram(compressed: str) -> str:
    """Decompress a draw.io compressed diagram XML string."""
    decoded = base64.b64decode(compressed)
    decompressed = zlib.decompress(decoded, -15)
    return urllib.parse.unquote(decompressed.decode('utf-8'))


def compress_diagram(xml_str: str) -> str:
    """Compress diagram XML back to draw.io compressed format."""
    encoded = urllib.parse.quote(xml_str, safe='')
    compressed = zlib.compress(encoded.encode('utf-8'), 9)
    # Strip zlib header (first 2 bytes) and checksum (last 4 bytes)
    raw = compressed[2:-4]
    return base64.b64encode(raw).decode('utf-8')


def update_diagram(input_path: str, output_path: str, data: dict,
                   compress: bool = False):
    """Update diagram cells based on service data."""
    tree = ET.parse(input_path)
    root = tree.getroot()

    # Handle both mxfile wrapper and bare mxGraphModel
    if root.tag == 'mxfile':
        for diagram_elem in root.findall('diagram'):
            # Check if diagram content is compressed
            text = diagram_elem.text
            if text and text.strip():
                # Compressed format
                xml_str = decompress_diagram(text.strip())
                model = ET.fromstring(xml_str)
                process_model(model, data)
                if compress:
                    diagram_elem.text = compress_diagram(
                        ET.tostring(model, encoding='unicode'))
                else:
                    diagram_elem.text = None
                    diagram_elem.append(model)
            else:
                # Uncompressed format
                model = diagram_elem.find('mxGraphModel')
                if model is not None:
                    process_model(model, data)
    elif root.tag == 'mxGraphModel':
        process_model(root, data)

    tree.write(output_path, encoding='UTF-8', xml_declaration=True)
    print(f'Updated diagram written to {output_path}')


def process_model(model: ET.Element, data: dict):
    """Process all object elements in an mxGraphModel."""
    updated = 0
    root_elem = model.find('root')
    if root_elem is None:
        return

    for obj in root_elem.iter('object'):
        service_id = obj.get('service-id')
        if not service_id or service_id not in data:
            continue

        service_data = data[service_id]
        cell = obj.find('mxCell')
        if cell is None:
            continue

        style = cell.get('style', '')

        # Update status color
        status = service_data.get('status', 'unknown').lower()
        colors = STATUS_COLORS.get(status, STATUS_COLORS['unknown'])
        style = update_style_property(style, 'fillColor', colors['fill'])
        style = update_style_property(style, 'strokeColor', colors['stroke'])

        # Update latency threshold coloring (for edge labels etc.)
        latency = service_data.get('latency_ms')
        if latency is not None:
            latency_colors = get_threshold_color(latency, [
                (100, {'fill': '#D5E8D4', 'stroke': '#82B366'}),
                (500, {'fill': '#FFF2CC', 'stroke': '#D6B656'}),
                (float('inf'), {'fill': '#F8CECC', 'stroke': '#B85450'}),
            ])
            style = update_style_property(style, 'fillColor',
                                          latency_colors['fill'])
            style = update_style_property(style, 'strokeColor',
                                          latency_colors['stroke'])

        cell.set('style', style)

        # Update object properties (for placeholder display)
        for key, value in service_data.items():
            obj.set(key, str(value))

        updated += 1

    # Update file-level timestamp
    now = datetime.now(timezone.utc).strftime('%Y-%m-%dT%H:%M:%SZ')
    for obj in root_elem.iter('object'):
        if obj.get('id') == 'header' or obj.get('type') == 'header':
            obj.set('last_updated', now)

    print(f'Updated {updated} service(s)')


def fetch_data(source: str) -> dict:
    """Fetch service data from URL or file."""
    if source.startswith('http://') or source.startswith('https://'):
        req = urllib.request.Request(source)
        req.add_header('Accept', 'application/json')
        try:
            with urllib.request.urlopen(req, timeout=30) as resp:
                return json.loads(resp.read().decode('utf-8'))
        except urllib.error.URLError as e:
            print(f'Error fetching data: {e}', file=sys.stderr)
            sys.exit(1)
    else:
        with open(source) as f:
            return json.load(f)


def main():
    parser = argparse.ArgumentParser(
        description='Update draw.io diagram with live service data')
    parser.add_argument('--input', '-i', required=True,
                        help='Input .drawio file')
    parser.add_argument('--output', '-o', required=True,
                        help='Output .drawio file')
    parser.add_argument('--data-url',
                        help='URL to fetch JSON service data')
    parser.add_argument('--data-file',
                        help='Path to JSON service data file')
    parser.add_argument('--compress', action='store_true',
                        help='Compress output diagram XML')
    args = parser.parse_args()

    if not args.data_url and not args.data_file:
        parser.error('Either --data-url or --data-file is required')

    source = args.data_url or args.data_file
    data = fetch_data(source)

    # Data format: {"service-id": {"status": "healthy", "latency_ms": 45, ...}}
    update_diagram(args.input, args.output, data, compress=args.compress)


if __name__ == '__main__':
    main()

Expected Data Format

The script expects JSON in this format:

{
  "svc-api-gateway": {
    "status": "healthy",
    "latency_ms": 42,
    "uptime": "99.97%",
    "requests_per_sec": 1250
  },
  "svc-auth-service": {
    "status": "warning",
    "latency_ms": 320,
    "uptime": "99.85%",
    "requests_per_sec": 450
  },
  "svc-database": {
    "status": "critical",
    "latency_ms": 1200,
    "uptime": "98.50%",
    "connections": 95
  }
}

Bash Script for CI/CD Integration

#!/usr/bin/env bash
# update-diagram-status.sh - Update draw.io diagram from health API
#
# Usage: ./update-diagram-status.sh <input.drawio> <output.drawio> <health-api-url>

set -euo pipefail

INPUT="${1:?Usage: $0 <input.drawio> <output.drawio> <health-api-url>}"
OUTPUT="${2:?Missing output path}"
API_URL="${3:?Missing health API URL}"

echo "Fetching service status from ${API_URL}..."
DATA=$(curl -sf --max-time 30 "${API_URL}")

if [ -z "$DATA" ]; then
    echo "ERROR: Empty response from health API" >&2
    exit 1
fi

# Write data to temp file
TMPDATA=$(mktemp)
echo "$DATA" > "$TMPDATA"

echo "Updating diagram..."
python3 "$(dirname "$0")/update_diagram.py" \
    --input "$INPUT" \
    --output "$OUTPUT" \
    --data-file "$TMPDATA"

rm -f "$TMPDATA"

echo "Diagram updated: ${OUTPUT}"

# Export to SVG for web display
if command -v drawio &>/dev/null || command -v xvfb-run &>/dev/null; then
    SVG_OUTPUT="${OUTPUT%.drawio}.drawio.svg"
    xvfb-run -a drawio --export --format svg --embed-diagram \
        --output "$SVG_OUTPUT" "$OUTPUT" 2>/dev/null || true
    echo "SVG exported: ${SVG_OUTPUT}"
fi

Cron Job Setup

Linux Cron

# Update diagram every 5 minutes
*/5 * * * * /path/to/update-diagram-status.sh /path/to/arch.drawio /path/to/arch-live.drawio https://api.example.com/health >> /var/log/diagram-update.log 2>&1

GitHub Actions Scheduled Workflow

name: Update Status Diagram

on:
  schedule:
    - cron: '*/15 * * * *'  # Every 15 minutes
  workflow_dispatch:

jobs:
  update:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Update diagram from API
        env:
          HEALTH_API_URL: ${{ secrets.HEALTH_API_URL }}
        run: |
          python3 scripts/update_diagram.py \
            --input docs/architecture.drawio \
            --output docs/architecture.drawio \
            --data-url "$HEALTH_API_URL"

      - name: Export to SVG
        run: |
          sudo apt-get install -y xvfb
          wget -q https://github.com/jgraph/drawio-desktop/releases/download/v24.7.17/drawio-amd64-24.7.17.deb
          sudo dpkg -i drawio-amd64-24.7.17.deb || sudo apt-get install -f -y
          xvfb-run -a drawio --export --format svg --embed-diagram \
            --output docs/architecture.drawio.svg docs/architecture.drawio

      - name: Commit changes
        run: |
          git config user.name "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"
          git add docs/architecture.drawio docs/architecture.drawio.svg
          git diff --cached --quiet || git commit -m "chore: update status diagram"
          git push

Webhook Handler for Real-Time Updates

Flask-based webhook handler that updates diagrams on service status changes:

#!/usr/bin/env python3
"""
webhook_handler.py - Receive status webhooks and update diagram in real-time.

Listens for POST requests with service status updates and regenerates
the diagram SVG.

Usage:
    python webhook_handler.py --diagram docs/architecture.drawio --port 8080
"""

from http.server import HTTPServer, BaseHTTPRequestHandler
import json
import subprocess
import threading
import argparse

# In-memory status store
service_status = {}
diagram_path = ''
lock = threading.Lock()


class WebhookHandler(BaseHTTPRequestHandler):
    def do_POST(self):
        content_length = int(self.headers.get('Content-Length', 0))
        body = self.rfile.read(content_length)

        try:
            payload = json.loads(body)
        except json.JSONDecodeError:
            self.send_response(400)
            self.end_headers()
            self.wfile.write(b'Invalid JSON')
            return

        # Expected: {"service_id": "svc-api", "status": "healthy", ...}
        service_id = payload.get('service_id')
        if not service_id:
            self.send_response(400)
            self.end_headers()
            self.wfile.write(b'Missing service_id')
            return

        with lock:
            service_status[service_id] = payload

        # Trigger async diagram update
        threading.Thread(target=update_diagram_async).start()

        self.send_response(200)
        self.end_headers()
        self.wfile.write(b'OK')

    def log_message(self, format, *args):
        print(f'[webhook] {args[0]}')


def update_diagram_async():
    """Write status to temp file and run update script."""
    with lock:
        data = dict(service_status)

    import tempfile
    with tempfile.NamedTemporaryFile(mode='w', suffix='.json',
                                      delete=False) as f:
        json.dump(data, f)
        tmp_path = f.name

    try:
        subprocess.run([
            'python3', 'update_diagram.py',
            '--input', diagram_path,
            '--output', diagram_path,
            '--data-file', tmp_path,
        ], check=True, timeout=30)
        print('[update] Diagram updated successfully')
    except subprocess.CalledProcessError as e:
        print(f'[update] Failed: {e}')
    finally:
        import os
        os.unlink(tmp_path)


def main():
    global diagram_path
    parser = argparse.ArgumentParser()
    parser.add_argument('--diagram', required=True)
    parser.add_argument('--port', type=int, default=8080)
    args = parser.parse_args()
    diagram_path = args.diagram

    server = HTTPServer(('0.0.0.0', args.port), WebhookHandler)
    print(f'Webhook listener on port {args.port}')
    server.serve_forever()


if __name__ == '__main__':
    main()

Send status updates via curl:

curl -X POST http://localhost:8080/ \
  -H "Content-Type: application/json" \
  -d '{"service_id": "svc-api-gateway", "status": "warning", "latency_ms": 350}'

Dashboard-Style Status Diagrams

Layout Pattern

Create a grid of service status cards:

<mxGraphModel>
  <root>
    <mxCell id="0"/>
    <mxCell id="1" parent="0"/>
    <!-- Title -->
    <mxCell id="title" value="Service Status Dashboard" style="text;fontSize=20;fontStyle=1;align=center;" vertex="1" parent="1">
      <mxGeometry x="50" y="10" width="500" height="30" as="geometry"/>
    </mxCell>
    <!-- Timestamp -->
    <object label="Last updated: %last_updated%" id="ts" placeholders="1" last_updated="2026-03-14T12:00:00Z">
      <mxCell style="text;fontSize=10;fontColor=#999999;align=center;placeholders=1;" vertex="1" parent="1">
        <mxGeometry x="50" y="40" width="500" height="20" as="geometry"/>
      </mxCell>
    </object>
    <!-- Service Cards Row 1 -->
    <object label="&lt;b&gt;%name%&lt;/b&gt;&lt;br&gt;%status%&lt;br&gt;%latency%" id="svc1" placeholders="1"
            service-id="svc-api-gateway" name="API Gateway" status="healthy" latency="42ms">
      <mxCell style="rounded=1;whiteSpace=wrap;html=1;placeholders=1;fillColor=#D5E8D4;strokeColor=#82B366;fontSize=11;" vertex="1" parent="1">
        <mxGeometry x="50" y="80" width="150" height="80" as="geometry"/>
      </mxCell>
    </object>
    <object label="&lt;b&gt;%name%&lt;/b&gt;&lt;br&gt;%status%&lt;br&gt;%latency%" id="svc2" placeholders="1"
            service-id="svc-auth" name="Auth Service" status="warning" latency="320ms">
      <mxCell style="rounded=1;whiteSpace=wrap;html=1;placeholders=1;fillColor=#FFF2CC;strokeColor=#D6B656;fontSize=11;" vertex="1" parent="1">
        <mxGeometry x="220" y="80" width="150" height="80" as="geometry"/>
      </mxCell>
    </object>
    <object label="&lt;b&gt;%name%&lt;/b&gt;&lt;br&gt;%status%&lt;br&gt;%latency%" id="svc3" placeholders="1"
            service-id="svc-database" name="Database" status="critical" latency="1200ms">
      <mxCell style="rounded=1;whiteSpace=wrap;html=1;placeholders=1;fillColor=#F8CECC;strokeColor=#B85450;fontSize=11;" vertex="1" parent="1">
        <mxGeometry x="390" y="80" width="150" height="80" as="geometry"/>
      </mxCell>
    </object>
  </root>
</mxGraphModel>

Heat Map Visualization

Map numeric values to a color gradient for heat map effects:

def value_to_heatmap_color(value: float, min_val: float, max_val: float) -> str:
    """
    Map a value to a green-yellow-red gradient.
    Low values = green, mid = yellow, high = red.
    """
    if max_val == min_val:
        return '#D5E8D4'

    ratio = (value - min_val) / (max_val - min_val)
    ratio = max(0.0, min(1.0, ratio))

    if ratio < 0.5:
        # Green to Yellow
        r = int(213 + (255 - 213) * (ratio * 2))
        g = int(232 + (242 - 232) * (ratio * 2))
        b = int(212 + (204 - 212) * (ratio * 2))
    else:
        # Yellow to Red
        t = (ratio - 0.5) * 2
        r = int(255 - (255 - 248) * t)
        g = int(242 - (242 - 206) * t)
        b = int(204 - (204 - 204) * t)

    return f'#{r:02X}{g:02X}{b:02X}'

Apply to cells for CPU usage, latency, error rates, or any numeric metric to create visual heat maps across your architecture diagram.

Diagram Templates for Monitoring

Architecture Status Template

Structure your diagram with these zones:

1. Header: Title, environment, last-updated timestamp
2. External: Users, CDN, DNS (gray zone)
3. Edge: Load balancers, API gateways (blue zone)
4. Application: Services, workers, queues (green/yellow/red per status)
5. Data: Databases, caches, storage (separate zone)
6. Legend: Color key for status meanings

Recommended Metadata Properties

Standardize across all service objects: