Rule-based Processing of Dynamic Linked Data

Tutorial at the European Semantic Web Conference (ESWC 2017)

May 28 — June 1, 2017 in Portorož, Slovenia

In his keynote at ESWC 2013, David Karger posed a challenge to build SWIFTTT, the Semantic Web If-This-Then-That. This is the tutorial on SWIFTTT.

Andreas Harth and Tobias Käfer

Institute AIFB, Karlsruhe Institute of Technology (KIT), Germany

Abstract

The goal of the tutorial is to introduce, motivate, and detail techniques for carrying out rule-based processing and manipulation of web data. Inspired by the growth in data available adhering to the Linked Data principles and the maturing specifications around the Web of Things, our tutorial aims to educate researchers and practitioners about how to access and process such data using rules. We start with explaining how to access data and follow links, while applying reasoning over the collected data to answer queries. We also explain how such queries can be processed over changing data. We then focus on how to actually change data accessible via a Read-Write Linked Data interface, given that many emerging areas, such as the Linked Data Platform, Social Linked Data or the Web of Things require write access. The presented topics will be connected to related work in the area of Linked Data, such as link traversal query answering approaches. We also point out related work in the area of dynamical systems, especially in the area of Read-Write Linked Data where currently practitioners are developing systems, but not much work is done with regard to the underlying principles. The tutorial concludes with a set of still unresolved research problems and open issues.

Goal

The goal of the tutorial is to introduce, motivate, and detail techniques for carrying out rule-based processing and manipulation of web data. That is, the participants will learn how to process and manipulate RDF data while embracing the assumptions of Linked Data and Web Architecture as codified under the name of Representational State Transfer (REST).

Intended Audience

Our intended audience are practitioners and theorists from the Linked Data and Semantic Web communities.

Prerequisites

We require basic knowledge of Linked Data, that is, of Uniform Resource Identifiers (URIs), the Hypertext Transfer Protocol (HTTP), the Resource Description Framework (RDF), RDF Schema and the SPARQL Protocol and RDF Query Language.

Although prior knowledge of reasoning and rules is a clear plus, we will also cover the basics of those technologies as relevant for our tutorial. We will introduce a rule-based language based on Notation3 (N3). Further, we will introduce the Linked Data Profile of the Web Ontology Language (OWL LD), a subset of the OWL2 RL profile. We will also introduce Representational State Transfer (REST) and the Linked Data Platform.

Learning Objectives

After completing our tutorial, the participants are able to:

The participants also are further able to:

Practical Sessions

The tutorial will include three practical sessions:

Duration

We plan a half-day tutorial, split into four logical blocks that last about three hours in total.

Content

Session 1: Querying Linked Data with Reasoning (60 min)

Presenter: Andreas Harth

In the first session, we introduce the Linked Data abstraction. We describe link-traversal query processing methods, and explain how reasoning is beneficial in scenarios where arbitrary data is accessed.

  1. 10 Min: Introduction and Overview, Linked Data abstraction
  2. 10 Min: Link traversal query processing ([Fionda et al. 2012], [Hartig 2014])
  3. 20 Min: Notation3 and deduction rules
  4. 10 Min: Combining rules with SPARQL query processing
  5. 10 Min: Evaluation of SPARQL queries while taking into account rule-based programs (practical session)

Session 2: Querying and Reasoning with Linked Data (40 min)

Presenter: Andreas Harth

In the second session, we introduce action rules that allow for the specification of HTTP requests in the consequent. We describe how these action rules can be used for link-traversal query processing methods, and explain how reasoning is beneficial in scenarios where arbitrary data is accessed.

Session 3: Traversing and Reasoning on Read-Write Linked Data (70 min)

Presenter: Tobias Käfer

In the third session, we generalise Linked Data and also consider the unsafe methods of HTTP. We start out with Tim Berners-Lee's Linked Data Design Issues, CRUD and REST going the way to the specification of the Linked Data Platform.

Next, we show how request rules containing unsafe requests can be used: To trigger actions, or to maintain state between runs of an otherwise stateless program. Moreover, there is a parallel to RESTful Web Service Composition. While a lot of work has been done on descriptions of services and orchestration ([Lanthaler and Guetl 2013], [Decker et al. 2008], [Alarcón and Wilde 2010], [Verborgh et al. 2012]), little has been done regarding orchestration and execution.

  1. 20 Min: Read-Write Linked Data abstraction
  2. 30 Min: Unsafe action rules and their application
  3. 20 Min: Evaluation of rule-based programs that are able to write data on the Internet of Things/Web of Things (practical session)

Session 4: Summary and Closing (10 Min)

Team of Presenters

Andreas Harth

Andreas Harth works as post-doctoral researcher at Institute AIFB at the Karlsruhe Institute of Technology (KIT) after pursuing a Ph.D. with the Digital Enterprise Research Institute (DERI) at the National University of Ireland, Galway. He recently successfully concluded the habilitation process at KIT. Andreas worked as intern at IBM’s Silicon Valley Lab in San Jose, CA, and visited USC’s Information Sciences Institute in Marine del Rey, CA as a research assistant. His research interests are large-scale data interoperation on the Semantic Web, Linked Data, knowledge representation, computational logic and user interaction on web data; he is co-developer of several systems, for example the Semantic Web Search Engine (SWSE), the VisiNav search interface and the Linked Data-Fu data processing system. Andreas has over 5 years of teaching experience and gave tutorials at ISWC, SIGMOD, and WWW conferences.

Tobias Käfer

Tobias Käfer is a Ph.D. student at the institute AIFB at Karlsruhe Institute of Technology (KIT) in Germany working under the supervision of Andreas Harth. His research is centered around the formalisation, observation, and execution of behaviour for the Linked Data Web. He worked in the EU-funded project i-VISION integrating the parts of a distributed Virtual Reality (VR) system using semantic web technologies such as Linked Data, REST, and Linked Data-Fu rules. He also worked in the EU-funded project PlanetData and the national projects ARVIDA and AFAP. He started the Dynamic Linked Data Observatory and worked as an intern at DERI, IBM, and Siemens. He was tutor for various computer science lectures at KIT.

References

[Alarcón and Wilde 2010] Restler: crawling restful services (poster). In Proceedings of the 19th International Conference on World Wide Web (WWW), pages 1051–1052, 2010.
[Decker et al. 2008] G. Decker, A. Lüders, H. Overdick, K. Schlichting, and M. Weske. RESTful Petri Net Execution. In Proceedings of the 5th International Workshop on Web Services and Formal Methods, (WS-FM), pages 73–87, 2008.
[Fionda et al. 2012] V. Fionda, C. Gutierrez, and G. Pirrò. Semantic navigation on the web of data: specification of routes, web fragments and actions. In Proceedings of the 21st Conference on World Wide Web (WWW), pages 281–290, 2012.
[Harth and Käfer 2016] A. Harth and T. Käfer. Towards specification and execution of linked systems. In Proceedings of the 28th GI-Workshop Grundlagen von Datenbanken (GvD), pages 62–67, 2016.
[Hartig 2014] O. Hartig. Linked data query processing based on link traversal. In Linked Data Management, pages 263–283. CRC Press, 2014.
[Käfer et al. 2013] T. Käfer, A. Abdelrahman, J. Umbrich, P. O’Byrne, and A. Hogan. Observing linked data dynamics. In Prodeedings of the 10th Extended Semantic Web Conference (ESWC), pages 213–227, 2013.
[Lanthaler and Guetl 2013] M. Lanthaler and C. Guetl. Hydra: A Vocabulary for Hypermedia-Driven Web APIs. In Proceedings of the 6th Workshop on Linked Data on the Web (LDOW), 2013.
[Stadtmüller et al. 2013] S. Stadtmüller, S. Speiser, A. Harth, and R. Studer. Data-fu: a language and an interpreter for interaction with read/write linked data. In Proceedings of the 22nd International Conference on World Wide Web (WWW), pages 1225–1236, 2013.
[Verborgh et al. 2012] R. Verborgh, T. Steiner, D. V. Deursen, S. Coppens, J. G. Vallés, and R. V. de Walle. Functional descriptions as the bridge between hypermedia APIs and the Semantic Web. In Proceedings of the 3rd International Workshop on RESTful Design (WS-REST) at the 21st International Conference on World Wide Web (WWW), pages 33–40, 2012.