Statement:38

Tags	API, Knowledge as a Service, Schema.org, Structural Semantics, Templates, Wikidata
Primary Session	Advancing the Contributor Experience
Secondary Sessions	Knowledge as a Service

PROBLEM

To satisfy the 'Knowledge as a service' theme, in addition to providing access to full page content, Wikimedia APIs should provide access to semantic units at: - an abstract document level (sections, headings, tables, etc.) - a domain specific level (infoboxes, geolocation, taxoboxes, etc.)

Wikitext, the core content creation technology on wikis, evolved as a string-processing language where one set of strings is replaced with another set of strings mostly via regular expression matches to yield the output HTML string. There is no notion of document structures here.

This lack of structural semantics gets in the way of being able to robustly identify semantic units and developing tools and features that operate on a page structurally at sub-page granularities.

SOLUTION: TRANSPARENT TYPING LAYER OVER WIKITEXT

Types improve abstraction, reasoning, and tooling abilities in programming languages. A transparent typing layer on top of wikitext can provide similar benefits.

A: ENFORCE STRUCTURAL TYPES ON OUTPUT OF WIKITEXT CONSTRUCTS INCLUDING TEMPLATES AND EXTENSIONS

- Specify that all wikitext constructs have an output with type:

 String, DOM, CSS property, HTML-attribute, or a List of one of those

- Extensions and templates can specify the expected output type. All other

 core wikitext constructs have the DOM output type.

- Parser enforces the output type of all wikitext constructs. Examples:

 For DOM types, unclosed tags and misnested tags are fixed up.
 For String types, HTML tags are escaped, wikitext strings are nowikied.
 For CSS types, values are sanitized.

Among other benefits, this basic typing mechanism enables MediaWiki to provide an API to extract and edit document fragments without introducing adverse side-effects on the rest of the page.

B: UNIFIED TYPING MECHANISM TO EXPOSE DOMAIN-SPECIFIC SEMANTIC INFORMATION

Editors impose structure in documents through a rich library of templates, policies, and maintainance processes they have developed over the years. If this semantic information (infoboxes, navboxes, sports rankings, railway timetables, etc) is mapped to a centralized ontology system (wikidata, schema.org, something else), the parser can expose this information in HTML and via MediaWiki APIs can expose this information in a wiki-neutral way.

There are multiple disparate mechanisms today wherein template authors specify metadata about templates (templatadata, templatestyles, possibly others?)

Instead of creating newer mechanisms for specifying structural output types and semantic information types for templates, it is better to provide a consolidated mechanism that unifies all this template metadata into a single user-defined type declaration. This lets newer applications and capabilities to be developed in the future without code changes to the core mechanism.

FEASIBILITY

This typing layer only affects template authors. Editors that use source editing won't see any impact (besides fewer markup errors). Editors that use visual editing might see improved tooling. Even for template authors, this is meant to be an opt-in mechanism with gradual migration over to the new model.

The proposal here is a logical extension of what Parsoid does today. Parsoid provides an illusion of structured wikitext and demonstrates what is possible (VE, CX, Linter, Flow among others) by embracing structured semantics.