DiffDetect

A REDAXO addon for monitoring changes on websites and RSS feeds. DiffDetect automatically creates snapshots of specified URLs and helps editors track modifications in various web sources over time.

Features

• URL Monitoring: Track changes on HTML web pages
• RSS Feed Monitoring: Monitor updates in RSS feeds with specialized diff view
• Automatic Snapshots: Create snapshots automatically via cronjob
• Visual Diff Display: Compare different versions with highlighted changes
• HTTP Authentication: Support for password-protected pages
• Console Command: Manual execution via command line
• Dashboard: Central overview of all monitored URLs with their status
• Flexible Intervals: Configure individual check intervals for each URL
• Categories: Organize URLs with tags/categories

Requirements

• REDAXO >= 5.15.1
• PHP >= 8.2
• YForm Addon >= 3.2
• Cronjob Addon >= 2.10.0

Installation

1. Install the addon via REDAXO backend under "AddOns"
2. The addon will automatically install required dependencies
3. Configure cronjobs for automatic monitoring (see Configuration section)

Usage

Adding URLs to Monitor

1. Navigate to AddOns > Diff Detection
2. Click on "URL hinzufügen" (Add URL)
3. Configure the following settings:
   • Name: A descriptive name for the URL
   • URL: The full URL to monitor
   • Type: Choose between HTML or RSS
   • Interval: Check interval in minutes
   • Categories: Optional tags for organization
   • HTTP Authentication: Optional login credentials

Viewing Changes

1. Go to the Dashboard to see all monitored URLs
2. Click on a URL to see its snapshot history
3. Select two snapshots to compare
4. The diff view will highlight all changes between versions

Manual Snapshot Creation

You can manually trigger snapshot creation:

• Via Backend: Click "Snapshot abrufen" for a specific URL
• Via Console: ./redaxo/bin/console diff_detect:execute

Configuration

Cronjob Setup

The addon uses REDAXO's cronjob system for automatic monitoring:

1. Go to AddOns > Cronjobs
2. Create a new cronjob
3. Select "DiffDetect: Snapshots erstellen und CleanUp durchführen"
4. Configure the execution interval (recommended: every 5-15 minutes)

URL Configuration Options

• Status: Active/Inactive - temporarily disable monitoring
• Interval: Minimum time between checks (in minutes)
• Type:
  • HTML: For regular web pages
  • RSS: For RSS/Atom feeds (uses specialized diff algorithm)
• HTTP Authentication: For password-protected pages

Technical Details

Database Structure

The addon creates two main tables:

• rex_diff_detect_url: Stores URL configurations
• rex_diff_detect_index: Stores snapshots and their content

How It Works

1. The cronjob checks for URLs that need updating based on their interval
2. For each URL, it fetches the current content
3. If changes are detected, a new snapshot is created
4. Old snapshots are kept for comparison
5. The diff algorithm highlights changes between versions

Diff Algorithms

• HTML Pages: Line-by-line comparison with whitespace normalization
• RSS Feeds: Item-based comparison that tracks new, changed, and removed feed items

Console Commands

# Execute diff detection manually
./redaxo/bin/console diff_detect:execute

Use Cases

• Monitor legal pages for compliance updates
• Track competitor websites for changes
• Watch news portals for specific topics
• Monitor RSS feeds for new content
• Check fact-checker websites for updates
• Track documentation pages for changes

Support

• GitHub: https://github.com/FriendsOfREDAXO/diff_detect
• Issues: Report bugs and feature requests on GitHub
• REDAXO Slack: Get help in the REDAXO community

License

This addon is licensed under the MIT License. See LICENSE file for details.

Credits

Developed by Friends Of REDAXO