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RDF Working Group Charter

The mission of the RDF Working Group, part of the Semantic Web Activity, is to update the 2004 version of the Resource Description Framework (RDF) Recommendation. The scope of work is to extend RDF to include some of the features that the community has identified as both desirable and important for interoperability based on experience with the 2004 version of the standard, but without having a negative effect on existing deployment efforts.

Join the RDF Working Group.

End date 30 June 2014
Confidentiality Proceedings are public
Initial Chairs David Wood, Talis
Guus Schreiber, Vrije Universiteit Amsterdam
Initial Team Contacts
Sandro Hawke (0.2 FTE)
Ivan Herman (0.2 FTE)
Usual Meeting Schedule Teleconferences: Weekly (full group), plus possible weekly for task forces
Face-to-face: 1-3 F2F meetings are planned per year, but chairs have to prerogative to call additional meetings if the work requires or decide not to call a F2F if budget or timing requirements make it difficult to organize.

Background

The Resource Description Framework (RDF), the first layer of the Semantic Web, became a W3C Recommendation in 1999. A major revision was published in 2004, including the general concepts, its semantics, and an XML Serialization (RDF/XML) syntax.

Since then, several newer standards based on RDF have been published, including SPARQL, OWL 2, POWDER, SKOS, and RIF. Through this standardization work, the thriving R&D activities in the area, and an ongoing deployment of these technologies across multiple industries, a number of issues regarding RDF came to the fore. In June 2010 the W3C held a workshop to gather feedback and begin to determine if another revision of RDF is warranted and, if so, which elements should be added or clarified. The workshop established a list of possible work items which was summarized by the report of the workshop. This was followed by a public discussion on various email lists and fora as well as a public questionnaire set up by W3C and which was answered by 126 people from the community. The current charter reflects a consensus reached through those discussions and responses.

Scope

Compatibility and Deployment Expectation

For all new features, backwards compatibility with the current version of RDF is of great importance. This means that all efforts should be made so that

  • any valid RDF graphs (in terms of the RDF 2004 version) should remain valid in terms of a new version of RDF; and
  • any RDF or RDFS entailment drawn on RDF graphs using the 2004 semantics should be valid entailment in terms of a new version of RDF and RDFS

Care should be taken to not jeopardize exisiting RDF deployment efforts and adoption. In case of doubt, the guideline should be not to include a feature in the set of additions if doing so might raise backward compatibility issues.

New Features and Changes

This charter provides two lists of features: "Required features" and "Time-permitting features". The former includes features whose inclusion in the final recommendations is required for the Working Group to successfully complete its charter, whereas the latter includes features that the Working Group should consider adding to the final recommendation, but which may be abandoned if the Working Group has insufficient time or resources, or the features would violate the backward compatbility or deployment concerns. The Working Group is expected to give priority in allocating resources to the required features until they are completed.

Beyond the explicit features listed below, the Working Group will also look at the official RDF Errata document and all formally recorded error reports, and introduce changes as appropriate.

Syntax

Required features
  • Standardize the Turtle RDF Syntax (see the Workshop result page for further references). Either that syntax or a related syntax should also support multiple graphs and graph stores (see work item listed below). This work should take into account the 14 January 2008 Turtle Syntax document, N3, TriG, and the SPARQL Query Language syntax.
  • Define and standardize a JSON Syntax for RDF (see the Workshop result page for further references). The goal is to provide an RDF serialization as complete as possible (including to multiple graphs and graph stores, see work item listed below), but features may be ignored and special syntax features may be introduced if that would greatly facilitate the adoption of the JSON encoding by the Web Application developers’ community.
Time permitting features
  • Standardize additions to RDF/XML to address some or all of the features of the Turtle and JSON syntaxes not currently expressable directly in RDF/XML, in a way which degrades gracefully in existing RDF/XML systems. Candidates include multiple graphs and graph stores (see work item listed below) or lists.
  • Standardize a subset of RDF/XML suitable for processing with standard XML tools like XSLT and XQuery (e.g., no typed nodes, no nesting, etc).

Support for Multiple Graphs and Graph Stores

The RDF Community has used the term "named graphs" for a number of years in various settings, but this term is ambiguous, and often refers to what could rather be referred as quoted graphs, graph literals, URIs for graphs, knowledge bases, graph stores, etc. The term "Support for Multiple Graphs and Graph Stores" is used as a neutral term in this charter; this term is not and should not be considered as definitive. The Working Group will have to define the right term(s).

Required features
  • Standardize a model and semantics for multiple graphs and graphs stores (see the Workshop result page for further references)

Changes/modification to the RDF concepts, model, or semantics

Required features
  • Clarify the usage of IRI references for RDF resources, e.g., per SPARQL Query §1.2.4.
  • Complete the inference rules that are currently incomplete, and update the entailment lemma (see Herman ter Horst’s paper for further details)
  • Deprecate some RDF features (e.g., reification, containers). "Deprecation" in this context means that new deployments, such as data publishers, are advised against using the feature. Conformant systems (parsers, etc) will still be required to implement the feature, i.e., the feature is not removed from the specification, nor is there a commitment that a future release of RDF would remove it.
  • Consider reconciling the core RDF(S) documents with semantic features and extensions defined by other W3C Recommendations since 2004 (for example rdf plain literals, the finite versions of the RDF and RDFS entailment regimes defined by SPARQL1.1, or the POWDER-S IRI Set Semantics). The goal is not to redefine those extensions and features, but rather to combine them into one or more, easily referencable document(s).
Time Permitting features
  • Harmonize the usage of different data types (or the lack thereof) for plain literals (i.e., XSD’s string and plain literal). The goal is to simplify, e.g., SPARQL queries that, at the moment, require to make three different queries for essentially identical purposes.

Miscellaneous

Required features
  • Update and extend the RDF Primer. New features may include multi-syntax examples, more up-to-date in terms of the vocabularies used, may deal with issues around Linked Data like the use of "owl:sameAs", the "follow-your-nose" algorithm, etc.

Out of Scope

Some features are explicitly out of scope for the Working Group

  • Changing the fundamentals RDF(S) semantics (e.g., usage of model theoretical semantics, interpretation of blank nodes). Note that minor improvements may be required by some of the work in the scope of the Working Group, which is still in the scope of the work.
  • Removing current restrictions in the RDF model (e.g., literals not allowed as subjects, or blank nodes as predicates)

Deliverables

The Working Group will publish a series of documents on the basis of the 2004 version of the RDF recommendation. I.e., the following documents may be updated:

but the Working Group may decide to re-structure these documents into another set of documents. How this is done is left to the discretion of the Working Group. Furthermore, it is also expected that two new documents will be published as W3C Recommendations, although, again, the exact document structure and titles are not defined by the charter and will be decided by the Working Group:

  • RDF Turtle Syntax Specification
  • RDF JSON Syntax Specification

The 2004 version of RDF also includes two more Recommendations: an RDF Primer and RDF Test Cases. Although the Working Group may update these documents, it may also decide to publish the new versions as W3C Working Group Notes.

Milestones

This section simply refers to "RDF Recommendation Set" as a collection of W3C Recommendations that together define the new version of RDF. The exact editorial structure of these documents is to be defined by the Working Group

Milestones
Note: The group will document significant changes from this initial schedule on the group home page.
Specification FPWD LC CR PR Rec or Note
RDF Recommendation Set May 2011 May 2012 August 2012 November 2012 January 2013
RDF Primer January 2012 June 2012 n/a November 2012(*) January 2013
RDF Test Cases May 2012 June 2012 August 2012 November 2012(*) January 2013
(*) In case the Working Group decides to publish the document as a W3C Note, then this step is non applicable.

Timeline View Summary

  • February 2011: First teleconference
  • April 2011: First face-to-face meeting
  • May 2011: Publication of the First Public Working Drafts for the RDF Recommendation Set
  • October/November 2011: Second face-to-face meeting
  • April 2012: Third face-to-face meeting
  • May 2012: Publication of the Last Call Working Draft for the RDF Recommendation Set
  • June 2012: Publication of the Last Call Working Draft for the RDF Primer and Test Cases
  • October/November 2012: Fourth face-to-face meeting
  • November 2012: Publication of the Proposed Recommendations
  • January 2012: Publication of all final documents

Dependencies and Liaisons

W3C Groups

Semantic Web Coordination Group
To ensure synchronization with all other Working and Interest Groups in the Semantic Web Activity.
Internationalization Activity
To ensure that the handling of RDF literals and resources make RDF usable for all possible encoding and languages; to ensure that the adoption of IRI-s abides to the requirements of Internationalization.
SPARQL Working Group
To synchronize on issues that might be taken over from the SPARQL Recommendations: IRI usage, usage of named graphs, RDF and RDFS Entailment Regimes.
RDFa Working Group
The RDF Working Group may decide to use RDFa 1.1’s @profile mechanism as part of the JSON and/or the Turtle Recommendations; in this case compatibility with the RDFa mechanism should be ensured.
Web Application Working Group
To ensure that the new version of RDF is better adapted to rich Web Clients (e.g., when making design choices on a JSON RDF Serialization)
XML Query Working Group
To ensure that the RDF/XML subset (in case it is defined by the group) is indeed suitable for processing with standard XML tools like XSLT and XQuery.

External Groups

IETF IRI Working Group
To cooperate on the usage of IRIs, both on the model and the syntax level

Participation

To be successful, the RDF Working Group is expected to have 10 or more active participants for its duration. Effective participation to RDF Working Group is expected to consume one work day per week for each participant; two days per week for editors. The RDF Working Group will allocate also the necessary resources for building Test Suites for each specification.

The Working Group welcomes participation from representatives of W3C Member organizations. To enable a broad spectrum of input, the group also anticipates the active participation of individuals as W3C Invited Experts (read the policy for approval of Invited Experts). Participation from W3C Members and non-Members alike will help ensure the goals of this charter are effectively addressed. Invited Experts in this group are not granted access to Member-only information.

Participants are reminded of the Good Standing requirements of the W3C Process.

Communication

This group primarily conducts its work on the public mailing list <public-rdf-wg@w3.org>.

Information about the group (deliverables, participants, face-to-face meetings, teleconferences, etc.) is available from the RDF Working Group home page.

Information about the group (deliverables, participants, teleconferences, etc.) is available from the RDF Working Group home page.

Decision Policy

As explained in the Process Document (section 3.3), this group will seek to make decisions when there is consensus. When the Chair puts a question and observes dissent, after due consideration of different opinions, the Chair should record a decision (possibly after a formal vote) and any objections, and move on.

  • When deciding a substantive technical issue, the Chair may put a question before the group. The Chair must only do so during a properly announced group meeting. When the Chair conducts a formal vote to reach a decision on a substantive technical issue, eligible voters may vote on a proposal one of three ways: for a proposal, against a proposal, or abstain. For the proposal to pass there must be more votes for the proposal than against. In case of a tie, the Chair will decide the outcome of the proposal.
  • This charter is written in accordance with Section 3.4, Votes of the W3C Process Document and includes no voting procedures beyond what the Process Document requires.

Patent Policy

This Working Group operates under the W3C Patent Policy (5 February 2004 Version). To promote the widest adoption of Web standards, W3C seeks to issue Recommendations that can be implemented, according to this policy, on a Royalty-Free basis.

For more information about disclosure obligations for this group, please see the W3C Patent Policy Implementation.

About this Charter

This charter for the RDF Working Group has been created according to section 6.2 of the Process Document. In the event of a conflict between this document or the provisions of any charter and the W3C Process, the W3C Process shall take precedence.


EDITED 2013年02月27日: End date modified to reflect extension granted. See previous version or diff.

EDITED 2014年02月13日: End date modified to reflect extension granted. See previous version or diff.

Sandro Hawke, Ivan Herman, W3C Staff Contacts, David Wood and Guus Schreiber, Working Group co-chairs

Copyright© 2011 W3C ® (MIT , ERCIM , Keio), All Rights Reserved.

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