REX: Web-Scale Extension of RDF Knowledge Bases

REX is an RDF extraction framework for Web data that can learn XPath wrappers from unlabelled Web pages using knowledge from the Linked Open Data Cloud.

API Documentation Issues Source Code Wiki

Introduction

The Web RDF Extraction Framework, REX, addresses the problem of extracting RDF data from templated websites. To this end, REX provide a generic architecture that allows learning XPath wrappers from unlabelled Web pages using knowledge from the Linked Open Data Cloud. REX is to be regarded as a skeleton that is to be fleshed out for your purposes. Still, REX is also a running system as it provides running implementations for all of its interfaces.

In contrast to existing frameworks to RDF extraction using XPath wrappers, REX provides a consistency layer which ensure that the new knowledge extracted is logically consistent with the knowledge already available in the input knowledge base. This website gives an overview of the framework. All technical details can be found on the Github page's wiki. There you will also find:

  • The Java documentation for the coders out there.
  • A manual to help you run the framework before you customize it for your purposes.
  • A ticket system in case you find some bugs or have some feature request.

Architecture

The REX Architecture

To facilitate the implementation of extraction processes, the framework provides the four layer-architecture shown in Figure 1. The data for the extraction is first to be gathered from the Web (or any other source of your choice). To this end, interfaces are provided. Each of the modules in each of the layers is provided as an interface. Moreover, an initial implementation of each interface is provided (see Java Docs).

  • The extraction layer allows for gathering data from the Web and consists of two modules: The crawler gathers website content from the Web while the domain identifier helps detecting web site domains that contain information pertaining to a given property.
  • The storage layer provides interfaces for managing and storing structured data as well as unstructured data.
  • The induction layer contains all modules that allow to learn XPath expressions. The core module here is the XPath Learner.
  • The generation layer allows integration approaches for generating and validating RDF data. The default generator relies on AGDISTIS and ORE.

Evaluation

With REX, we also aimed to provide a baseline system for the extraction of RDF from templated websites. Thus, in addition to providing at least one implementation for all the interfaces, we also evaluated the basic REX. The data we used for the evaluation can be found here.

What next?

There are several things you can do.

  1. Run REX: Simply follow the steps in the manual.
  2. Extend REX: Please check out the installation instructured.
  3. Point out bugs: Please use the issue tracker.

Now you're on. Please extend REX and help improving the extraction of RDF from the Web.

Project Team

Former Members

Publications

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News

DBpedia @ Google Summer of Code – GSoC 2017 ( 2017-03-13T11:12:50+01:00 Christopher Schulz)

2017-03-13T11:12:50+01:00 Christopher Schulz

DBpedia, one of InfAI’s community projects, will be part of the 5th Google Summer of Code program. The GsoC has the goal to bring students from all over the globe into open source software development. Read more about "DBpedia @ Google Summer of Code – GSoC 2017"

New GERBIL release v1.2.5 – Benchmarking entity annotation systems ( 2017-03-10T11:49:51+01:00 by Ricardo Usbeck)

2017-03-10T11:49:51+01:00 by Ricardo Usbeck

Dear all, the Smart Data Management competence center at AKSW is happy to announce GERBIL 1.2.5. Read more about "New GERBIL release v1.2.5 – Benchmarking entity annotation systems"

DBpedia Open Text Extraction Challenge – TextExt ( 2017-03-09T12:15:57+01:00 Christopher Schulz)

2017-03-09T12:15:57+01:00 Christopher Schulz

DBpedia, a community project affiliated with the Institute for Applied Informatics (InfAI) e.V., extract structured information from Wikipedia & Wikidata. Now DBpedia started the DBpedia Open Text Extraction Challenge – TextExt. Read more about "DBpedia Open Text Extraction Challenge – TextExt"

The USPTO Linked Patent Dataset release ( 2017-02-24T17:18:51+01:00 by Mofeed Hassan)

2017-02-24T17:18:51+01:00 by Mofeed Hassan

Dear all, We are happy to announce USPTO Linked Patent Dataset release. Patents are widely used to protect intellectual property and a measure of innovation output. Read more about "The USPTO Linked Patent Dataset release"

Two accepted papers in ESWC 2017 ( 2017-02-22T17:43:38+01:00 by Dr. Mohamed Ahmed Sherif)

2017-02-22T17:43:38+01:00 by Dr. Mohamed Ahmed Sherif

Hello Community! We are very pleased to announce the acceptance of two papers in ESWC 2017 research track. The ESWC 2017 is to be held in Portoroz, Slovenia from 28th of May to the 1st of June. Read more about "Two accepted papers in ESWC 2017"