Ontology Outreach Advisory

Since it completed the Recommendation Track process last year, little has been said or written about POWDER. However, there have been a number of unrelated events recently that I take as evidence of a long term future. As chair of the WG that created it (and an editor of all but one of the documents and general front-person for the whole thing), this makes me happy!

One of my private measures of success for it has always been that one day, someone I don't know and who doesn't know me stands up at a big conference and says "you know this POWDER thing is really cool." That happened at SemTech last month when Matt Fisher presented it in a session called RDF Friday Part 3: Practical RDF - POWDER & Object Design Patterns. The full version of what he was saying is available in an article on his company website Putting POWDER to Work. Matt and I have exchanged e-mails since then but we hadn't had any contact before.

Secondly my friend and WG member Andrea Perego has been cooking up some code that uses POWDER to generate RDFa in a way that could make it really easy to add all those <link /> elements in documents on the fly under the control of a single, central POWDER file.

Suppose you want to add RDFa to all the pages on your Web site (not a bad thing to do!). One can imagine doing this for Creative Commons licences, DC metadata etc. Something like

These link elements should probably be included on every page of your site. Sounds like a job for POWDER. Andrea's PHP POWDER Processor (3P) can take a POWDER file and URI as inputs and return those RDFa link elements via a RESTful API - one that could easily be called from within an authoring tool. Full documentation, including an example using the Open Graph Protocol, is available.

Another development is still under wraps at the moment but the signs are very positive that a combination of marketing expertise, industry contacts, business dynamism and, not unimportantly, venture capital is coming together in a POWDER-fuelled start-up.

A quick reminder of the key features of POWDER:

• it allows you to associate a bunch of predicates and objects with any number of subjects (as Dan Brickley puts it: it solves the aboutEachPrefix issue);
• it's primary format is XML, a small amount of which can describe a large amount of content;
• it has an associated GRDDL transform that renders the data as semantically-equivalent OWL;
• a POWDER processor returns RDF triples;
• the provenance of the data is always declared.

If you haven't looked at POWDER before, maybe now's a good time to do so.

Today W3C published a new standard for building rule systems on the Web. Declarative rules allow integration and transformation of data from multiple sources in a distributed, transparent and scalable manner. The new standard, called Rule Interchange Format (RIF), was developed with participation from the Business Rules, Logic Programming, and Semantic Web communities to provide interoperability and portability between many different systems using declarative technologies. For more information, see the RIF FAQ.

The six new standards are:

• RIF Core Dialect, which provides a standard, base level of functionality for interchange
• RIF Basic Logic Dialect and RIF Production Rule Dialect provided extended functionality matching two common classes of rule engines
• RIF Framework for Logic Dialects describes how to extend RIF for use with a large class of systems
• RIF Datatypes and Built-Ins 1.0 borrows heavily from XQuery and XPath for a set of basic operations
• and RIF RDF and OWL Compatibility specifies how RIF works with RDF data and OWL ontologies.

Along with these standards, W3C today published five related documents: RIF Overview, RIF Test Cases, OWL 2 RL in RIF, RIF Combination with XML data, and RIF In RDF. The RIF Working Group is also preparing a primer and a revision of its outdated Use Cases and Requirements.

The SPARQL Working Group has published a First Public Working Draft of SPARQL 1.1 Federation Extensions, which defines extensions to the SPARQL Query Language to support distributed SPARQL query execution. The group also published 5 updates, listed below. The group seeks feedback, particularly on open issues identified in each document.

• SPARQL 1.1 Query adds support for aggregates, subqueries, projected expressions, and negation to the SPARQL query language.
• SPARQL 1.1 Update defines an update language for RDF graphs.
• SPARQL 1.1 Service Description defines a vocabulary and discovery mechanism for describing the capabilities of a SPARQL endpoint.
• SPARQL 1.1 Uniform HTTP Protocol for Managing RDF Graphs describes the use of the HTTP protocol for managing named RDF graphs on an HTTP server.
• SPARQL 1.1 Entailment Regimes defines conditions under which SPARQL queries can be used with entailment regimes such as RDF, RDF Schema, OWL, or RIF.

The Rule Interchange Format (RIF) Working Group has published six Proposed Recommendations. Together, they allow systems using a variety of rule languages and rule-based technologies to interoperate with each other and with Semantic Web technologies.

Three of the drafts define XML formats with formal semantics for storing and transmitting rules:

• The RIF Production Rule Dialect (PRD) is designed for the kinds of rules used in modern Business Rule Management systems.
• The RIF Basic Logic Dialect (BLD) is a foundation for Logic Programming, classical logic, and related formalisms.
• The RIF Core Dialect is the common subset of PRD and BLD, useful when having a ubiquitous platform is paramount.

The other drafts:

• RIF Datatypes and Builtins (DTB) specifies the datatypes and standard operations (modeled on XPath Functions) available in all RIF dialects
• RIF RDF and OWL Compatibility specifies how RIF works with RDF, RDFS, OWL 1, and OWL 2.
• RIF Framework for Logic Dialects (FLD) provides a mechanism for specifying extended dialects, beyond BLD, when more expressive power is required.

The group has also published a new version of RIF Test Cases, and three other Working Drafts: RIF Overview, RIF Combination with XML data and OWL 2 RL in RIF.

RIF implementation information is available. Review comments are welcome until 8 June.

The RDFa Working Group has published the First Public Working Drafts of RDFa Core 1.1 and XHTML+RDFa 1.1. RDFa Core is a specification for attributes to express structured data in any markup language. XHTML+RDFa 1.1 is an application of RDFa Core 1.1 for XHTML. Both of these documents are expected to supersede the RDFa in XHTML (RDFa 1.0) specification. Together, these specifications enable the human-readable and machine-readable markup of people, places, events, products, recipes, social networks, and many other concepts that are frequently published on the web. These documents improve upon RDFa 1.0 by adding a number of Web community requested features to ease authoring. Comments are welcome and should be sent to the public-rdfa-wg@w3.org mailing list (see also the archives).

• A proposed set of provenance dimensions to organize major issues for provenance on the web
• More than 30 use cases developed by the group that cover all those dimensions illustrating a broad range of usage of provenance
• More than 250 user and technical requirements for provenance motivated by those use cases