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This is Revision: 1.14 $ Date: 2012-03-19 13:31:18 $

Linked Data Platform (LDP) Working Group Charter

The mission of the Linked Data Platform (LDP) Working Group is to produce a W3C Recommendation for RESTful application integration patterns using read/write Linked Data. This work will benefit both small-scale in-browser applications (WebApps) and large-scale Enterprise Application Integration (EAI) efforts. It will complement SPARQL and will be compatible with standards for publishing Linked Data, bringing the data integration features of RDF to RESTful, data-oriented software development.

Start Date 1 June, 2012
End date 1 June, 2014
Confidentiality Proceedings are public
Chairs @@@ TBD
@@@ TBD
Staff Contact
@@@ TBD (0.4 FTE total, two people)
Teleconference Schedule One 60-90 minute call per week, plus task force calls as necessary
Face-to-Face Meetings Three expected, although the chairs may schedule or cancel meetings as needed to help the group reach its goals. These meetings will use teleconferencing facilities, but effective participation generally requires attending in person, so participants should budget for travel.

Introduction

The basic approach of combining REST and RDF has been proposed and explored for some time [1][2][3][4], but its use has only recently been reported in industry [5]. Within W3C, the SPARQL Working Group developed a RESTful protocol for accessing data in SPARQL Graph Stores, and the group discussed its wider applicability. Last December, the participants Linked Enterprise Data Patterns Workshop expressed general support for the creation of a Working Group to define a way to use REST with RDF for application integration.

The basic technique here is to expose application data objects ("resources") on the Web, allowing authorized clients to see and modify object state using HTTP operations (GET, PUT, etc) with an RDF data format. This RESTful approach leverages existing Web technology, including caching, linking, and indexing, and the use of RDF facilitates integration of data across systems and applications. This approach dovetails with SPARQL and is positioned for developers who want more direct access to the application data.

The Linked Data Platform is envisioned as an enterprise-ready collection of standard techniques and services based on REST and the W3C Semantic Web stack. Simple LDP applications can be developed and deployed using only RDF with minor extensions to an existing HTTP infrastructure. More extensive LDP applications can be built using other elements of the stack, including RDFS, SPARQL, OWL, RIF, and Prov. Although expertise in these specialized elements may be helpful, it is not necessary for participation in this group and should not be required for using the Linked Data Platform.

Scope

The starting point for this group is [the potential submission discussed at the LEDP Workshop, expected to be similar to Basic Profile for Linked Data]. Using this document and any similar contributions from Working Group participants, the group is to produce one or more W3C Recommendations which define a RESTful way to use read/write Linked Data, suitable for use in application integration and the construction of open systems.

The group must also produce supporting materials, such as a description of uses cases, a list of requirements, and a test suite and/or validation tools to help ensure interoperability and correct implementation.

Parts of this work may overlap with general Linked Data patterns and best practice. When they do, the group must take special care to coordinate with other stakeholders who might not otherwise be interested in the group's work. For example, the group may give advice on how to design URIs for long-term stability, as needed for its use cases. This issue is also in scope for the Government Linked Data (GLD) Working Group which is producing Best Practices advice for governments publishing Linked Data. On issues like this, the two groups must coordinate to make sure their advice is compatible.

The Working Group will not normatively specify solutions for access control and authentication for Linked Data. However the Working Group will identify, based on a set of real world use cases, requirements for necessary authentication and authorization technologies.

Technical Issues

To help explain the work expected of the group, here is a list of practical issues, many of which are addressed in [@@@ the expected submission] that can arise in trying to use RDF and REST for application integration. These issues and ones like them should be discussed by the group and guidance provided in the delivered Recommendation when practical.

  1. Which RDF datatypes must be supported by clients and servers?
  2. Which RDF serialization syntax (eg Turtle or JSON-LD) must be supported by clients and servers?
  3. How to create a new resource, which might be a new collection?
  4. How to create a resource with information describing the resource, when the resource address isn't known at creation time?
  5. How to access resource state in reasonably-sized chunks (paging)?
  6. How to safely (predictably) modify a resource simultaneously from multiple clients? (concurrency)
  7. Can resource have multiple rdf:types? Can their rdf:types change?
  8. How can a client modify a resource without replacing the complete contents?
  9. How to get a list of all the resources in collection?
  10. How to move a resource in or out of a collection?
  11. How a client can determine whether/how it can modify a resource?
  12. How to operate on multiple resources at once, for efficiency?
  13. How to integrate with SPARQL, including how to find a SPARQL endpoint serving data for a particular resource? (To be coordinated with SPARQL community/WG.)
  14. Which vocabulary terms are to be used for resource metadata, when necessary for interoperation?
  15. Are there situations where use of blank nodes is allowed/disallowed?
  16. How to guide to a client about which RDF vocabulary terms to expect and to use when reading/writing resource state?

Answering these question may involve such work as:

Deliverables

  • Use Case and Requirements: a collection of use cases and a derived list of requirements that gives a practical foundation with which to analyze proposed designs for elements of the platform. The group will chose the form of this deliverable, such as a set of wiki pages.
  • Linked Data Platform: W3C Recommendation(s) defining a platform based on RESTful read/write Linked Data, detailed in Scope.
  • Test Suite and/or Validator: to help ensure interoperability and correct implementation. The group will chose the form of this deliverable, such as a git repository.
  • Access Control: Working Group Note on Use Cases and Requirements for access control and authentication mechanisms needed for this work.

Schedule

The group will document significant deviations from this schedule on its home page.

DateEventDescription
2012-05StartGroup Launch, First Teleconferences
2012-06UCRRelease initial lists of proposed Use Cases and Requirements
2012-09F2F1Face-to-face meeting
2012-10WD1First public Working Drafts published
2013-01WD2Second public Working Drafts published
2013-03F2F2Face-to-face meeting
2013-05LCWDLast Call Working Drafts published
2012-06F2F3Face-to-face meeting, if needed
2013-10CRCandidate Recommendation published
2014-01PRProposed Recommendation published
2014-03RECRecommendation published

Dependencies and Liaisons

W3C Groups

Liaisons

Dependencies

  • RDF Working Group: This group is chartered to produce Recommendations for Turtle and a JSON syntax for RDF. One of these syntaxes might be chosen as the standard RDF serialization for LDP.

Participation

In general, people participate in this group as representatives of W3C member organizations. At least one representative from each participating organization is expected to devote significant time to this effort (about one day per week, or more, depending on duties), to accept and complete appropriate action items on a timely basis, and to travel to face-to-face meetings, as scheduled by the chairs in consultation with the group.

On a case-by-case basis, using the invited expert process, people may be allowed to participate as individuals, not representing an organization.

To be successful, the Working Group is expected to have between ten and thirty active participants for its duration.

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

Communication

This group primarily conducts its work on the mailing list public-ldp-wg@w3.org (public archives). The mailing list member-ldp-wg@w3.org (W3C member-access-only archives) may be used for administrative purposes, such as travel planning.

Information about the group (deliverables, participants, face-to-face meetings, teleconferences, etc.) will be available from the group's 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.

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 Linked Data Platform 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.


Alexandre Bertails (bertails@w3.org), Sandro Hawke (sandro@w3.org), and Ivan Herman (ivan@w3.org), editors

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