Introduction to Semantic MediaWiki

What is Semantic MediaWiki?

Semantic MediaWiki (SMW) is a powerful MediaWiki extension that lets you turn a regular wiki into a collaborative knowledge base. By adding simple #set and #ask markup, you can store structured data (properties and values) directly on wiki pages and query that data across the whole wiki.

Key Concepts

• Properties: Named attributes (e.g., Has author, Published on) that describe a page.
• Values: The data attached to a property – can be strings, numbers, dates, coordinates, etc.
• Queries: Inline queries using #ask or the special page Special:Ask to retrieve pages that match certain criteria.
• Concepts: Saved query definitions that can be reused like virtual categories.

Why Use SMW?

SMW turns a wiki into a lightweight database without needing a separate DBMS. It enables:

• Dynamic tables, charts, maps, and timelines (via Semantic Result Formats).
• Faceted browsing with Semantic Drilldown.
• Complex compound queries (Semantic Compound Queries).
• Integration with forms (Page Forms) for easy data entry.

Installation Overview

# Using Composer (recommended)
composer require mediawiki/semantic-media-wiki

# In LocalSettings.php
wfLoadExtension( 'SemanticMediaWiki' );

# Run the update script
php maintenance/update.php --quick

SMW requires MediaWiki 1.43+ and PHP 8.1+. No database schema changes are needed beyond the tables created by the update script.

Essential Configuration

$smwgEnableInlineQueries = true;   // Allow #ask in page content
$smwgNamespacesWithSemanticLinks[NS_MAIN] = true; // Enable semantics on the main namespace
$smwgAutoRefreshOnPurge = true;   // Refresh query results when a page is purged

These settings are a good starting point; most wikis keep the defaults.

Typical Use‑Case Walkthrough

Visualise on a map (requires the Maps extension):

{{#ask: [[Category:Place]]
|?Has coordinates
|format=leaflet}}

Query the data with an inline ask:

{{#ask: [[Category:Book]]
|?Has author
|?Published on
|format=table}}

This renders a live table of all books with their authors and dates.

Create a property on a wiki page:

[[Has author::J. Doe]]
[[Published on::+2023-05-12]]
[[Has ISBN::978‑3‑16‑148410‑0]]

Related Extensions Worth Exploring

• Semantic Result Formats – additional output formats (charts, calendars, etc.).
• Semantic Drilldown – faceted navigation.
• Semantic Compound Queries – combine several queries into one view.
• Page Forms – generate forms for data entry.
• Semantic Watchlist – watch changes to specific properties.

Getting Help

The official documentation lives on the SMW wiki (semantic-mediawiki.org). For community support, use the semwiki-user mailing list and the talk page on mediawiki.org.

This post is a draft – feel free to expand sections, add screenshots, or link to real‑world examples.