Comunica: a Modular SPARQL Query Engine
for the Web

Querying Linked Data on the Web
is a multifaceted story

• Query languages and extensions
• Publication interfaces
• Querying algorithms
• ...

This variety of facets leads to comparability problems

Alternative algorithms are implemented in different engines → unfair!

Need for a flexible query engine
where various querying techniques
can be implemented and compared

Need for a flexible engine to compare alternative algorithms

Need for a flexible query engine
where various querying techniques
can be implemented and compared

Modularity using the actor model

Logic is separated into different actors.

Each actor independently performs a specific task.

• JSON-LD parsing actor
• SPARQL union actor A
• SPARQL union actor B

Actors can be combined for solving more complex tasks.

Actors subscribe to task-specific buses.

Mediators are responsible for selecting an actor to solve a certain task.

Example: Parse as fast as possible

Modules are wired together through semantic configuration files

Components.js: a semantic dependency injection framework.

Configuration files declare and parameterize actors, mediators and buses.

Implementation details

• Open-source under MIT license
• Implemented in TypeScript/JavaScript
• 114 separate modules (actors, buses, mediators)
• 1619 unit tests with a coverage of 100%
• Compatible with JavaScript API specification of RDFJS (W3C community group)

Current features

• Nearly full SPARQL 1.1 support Handled with an internal SPARQL algebra
• GraphQL queries GraphQL is translated to SPARQL algebra
• Federated querying of heterogeneous sources: Any combination of sources
• • Linked Data document
  • Triple Pattern Fragment
  • SPARQL endpoint
  • HDT files
  • RDFJS Source

Federate over any set of sources
from your browser

Using Comunica

• in your browser:

  http://query.linkeddatafragments.org/

• in JavaScript applications:

  Node.js: npm install @comunica/actor-init-sparql
  Browser: https://github.com/rdfjs/comunica-browser

• for development:

  https://github.com/comunica/comunica/

• → Documentation:

  https://comunica.readthedocs.io/en/latest/

• Fair.

• Modular.

• For everyone.

http://comunica.linkeddatafragments.org/