These are the community and working groups that KNoWS is contributing to or has contributed to.

Community groups


Hydra Community Group

Building Web APIs seems still more an art than a science. How can we build APIs such that generic clients can easily use them? And how do we build those clients? Current APIs heavily rely on out-of-band information such as human-readable documentation and API-specific SDKs. However, this only allows for very simple and brittle clients that are hardcoded against specific APIs. Hydra, in contrast, is a set of technologies that allow to design APIs in a different manner, in a way that enables smarter clients. The foundation is laid by the Hydra Core Vocabulary. It defines a number of fundamental concepts, such as hypermedia controls and collections, which allow machines to understand how to interact with an API. Since all information about the API is available in a machine-readable form, completely generic clients become possible. The Core Vocabulary is complemented by Linked Data Fragments, a set of specifications that enable advanced yet efficient client-side querying of Web APIs. More information about these technologies can be found on our homepage.

Knowledge Graph Construction Community Group

The overall goal of this community group is to support its participants into developing better methods for Knowledge Graphs construction. The Community Group will (i) study current Knowledge Graph construction methods and implementations, (ii) identify the corresponding requirements and issues that hinter broader Knowledge Graph construction, (iii) discuss use cases, (iv) formulate guidelines, best practices and test cases for Knowledge Graph construction, (v) develop methods, resources and tools for evaluating Knowledge Graphs construction, and in general (vi) continue the development of the W3C-recommended R2RML language beyond relational databases. The proposed Community Group could be instrumental to advance research, increase the level of education and awareness and enable learning and participation with respect to Knowledge Graph construction.

Notation 3 (N3) Community Group

Further development, implementation, and standardization of Notation 3 - an assertion and logic language - including the N3 Rules language.

RDF JavaScript Libraries Community Group

The RDF JavaScript Libraries Community Group discusses implementations of libraries for working with RDF and Linked Data in ECMAScript platforms like Web browsers and Node.js.

RDF Surfaces Community Group

The RDF Surfaces sets out to create a sublanguage of Notation3 in order to implement classical first-order logic with negation in RDF as envisioned by Pat Hayes in his 2009 ISWC Invited Talk: BLOGIC.

SPARQL 1.2 Community Group

The SPARQL 1.2 Community Group is a forum for discussion and refinement of SPARQL 1.1. It will document features found as extensions to available triple stores and also document common needs from the user community. The CG aims to create consensus and understanding of the impact of new features with special emphasis on features that leave existing SPARQL 1.1 queries and systems unchanged. The CG will build a collection of such features leading to a CG report on use cases and requirements.

Semantic HTML-vocabulary Community Group

The mission of this community group is to establish a draft standard for a RDF-based representation of the HTML-vocabulary. With the HTML-vocabulary in RDF, any type of an HTML-document can be meaningfully represented, generated and validated using nothing but standard semantic technologies, without any vendor lock-in. In addition, full provenance can be provided for a generated HTML-document, as every atom of the document can be described and semantically enriched, ex ante (RDF) and ex post (Rdfa). For instance, the originating algorithm that calculates a certain budget amount in a governmental HTML-document can be linked to the table cell containing the very value. HTML-documents have a wide variety of use and so has the HTML vocabulary. The HTML-vocabulary can be used to generate 100% correct HTML or xHTML and to validate this. The HTML vocabulary can be used to model the front end of a website or application, whereas the logic behind the front end can be captured in SHACL Advanced Features, making for a full semantic representation and execution of digital infrastructure, without any vendor lock-in. An HTML-document can be generated with full compliance to laws and regulations, as these norms can be linked and applied while using the HTML-vocabulary. With full provenance, an HTML-document can battle fake news and show realtime how certain sensitive data in the document (privacy, security) was derived. The community group will come up with a 0.1 draft specification. This will be input for a future working group within W3C. The community group can make use of the currently available draft specification as developed by the Dutch Ministry of Finance in a working prototype for the Dutch governmental budget cycle. By starting this community group, the Dutch Ministry wants to contribute to an open source based digital infrastructure.

Solid Community Group

The aims of the Solid project are in line with those of the Web itself: empowerment towards an equitable, informed and interconnected society. Solid adds to existing Web standards to realise a space where individuals can maintain their autonomy, control their data and privacy, and choose applications and services to fulfil their needs.

The mission of the Solid Community Group is to describe how Solid servers and clients can be interoperable by using Web communication protocols, global identifiers, authentication and authorization mechanisms, data formats and shapes, and query interfaces.

TREE Hypermedia Community Group

The TREE hypermedia community group will discuss materializable hypermedia interfaces. Its goals are to:

  1. Further evolve the TREE hypermedia specification ( and its vocabulary (
  2. Create a test suite for spec compliance of both servers and clients.
  3. Deliver a specification on view definitions for source selection.


Digital Publishing Community Group

The growth of the tablet and eReader market, and changes in scholarly publishing, have shown the accelerating impact of the Open Web Platform on digital publishing. For example, ePUB 3.0 no longer subsets W3C standards like HTML5, CSS, SVG, MathML, and Javascript APIs, but uses them in full. It also extends them to cover the various needs of digital publishing. These extensions, and continuing fragmentation among devices, formats, publishers, and distribution networks, suggest an opportunity for W3C to address publishing industry use cases, from novels and prose through to scientific and scholarly publishing, medical and legal publishing, interactive children's books, magazines and more. The initial aim of the Digital Publication Community Group will be to determine if W3C should invest more heavily in digital publication, and if so, what role it should play. The CG will establish and strengthen active liaisons with existing digital publishing fora, such as the International Digital Publishing Forum (IDPF) which oversees the ePUB specification, as well as digital publishers and distributors of all types. The Digital Publication Community Group will also explore the idea of one or more workshop on the topic, and provide a forum for open discussions on the future of digital publishing, specifically:

  • reducing market fragmentation
  • describing traditional and emerging publishing workflows, from the technology perspective
  • creating scenarios and requirements to drive future standardization in W3C Working Groups, including layout, internationalization, security, accessibility, content protection, metadata, and vocabularies.

This group will not publish Specifications.

This Community Group closed on 5 December 2013. For discussion on this topic, please refer to the Digital Publishing Interest Group.

Working groups


JSON-LD Working Group

The Working Group maintains the JSON-LD specifications (i.e., JSON-LD 1.1, JSON-LD 1.1 API, JSON-LD 1.1 Framing) that together provide a JSON format for Linked Open Data to interoperate at web-scale, in a method which is familiar to and usable by web-focused software engineers.


Linked Data Platform Working Group

Mission: produce a W3C Recommendation for HTTP-based (RESTful) application integration patterns using read/write Linked Data. (See Charter)

The LDP WG is now closed. As of 28 July 2015, the WG has finished wrapping things up by publishing the remaining specs as Working Group Notes. Having produced the LDP 1.0 Recommendation and explored the possibility of chartering a new WG (see Linked Data 2015 report and public mailing list), the WG decided to pursue discussions on LDP Next in a Community Group. If you're interested in working on LDP, please, join the LDP Next CG!

Media Annotations Working Group

The mission of the Media Annotations Working Group, part of the Video in the Web Activity, is to provide an ontology and API designed to facilitate cross-community data integration of information related to media objects in the Web, such as video, audio and images..

The Media Annotations Working Group was closed on 30 May 2014, having successfully published the following Recommendations: the Ontology for Media Resources 1.0 and the Metadata API for Media Resources 1.0.

Media Fragments Working Group

The mission of the Media Fragments Working Group, part of the Video in the Web Activity, was to address temporal and spatial media fragments in the Web using Uniform Resource Identifiers (URI).

The Media Fragments Working Group was closed on 5 December 2013, having successfully published the Media Fragments URI 1.0 (basic) specification as a Recommendation. Some ideas and removed parts of the Basic specifications were published in Media Fragments 1.0 URI (advanced) and might be reused by re-opening the Group or taken by another W3C Working Group.

Provenance Working Group

Mission: to support the widespread publication and use of provenance information of Web documents, data, and resources. The Working Group will publish W3C Recommendations that define a language for exchanging provenance information among applications.

After a successful publication of the PROV Ontology and related Notes (see PROV Overview for more details), this group has been closed on the 19th of June, 2013. For more information, related tools, etc, consult the PROV page of the Semantic Web Wiki, which is maintained by the community.