Tomáš Knap

ODCleanStore: a framework for managing and providing integrated linked data on the web

We present an ODCleanStore framework (1) enabling management of Linked Data on the Web and (2) providing web applications with a possibility to consume cleaned and integrated Linked Data according to their needs.

Linked data support for filing public contracts

Abstract Management of the tendering phase of the public contract lifecycle is a demanding activity with often irrevocable impact on the subsequent realization phase. We investigate the impact of the linked data technology on this process. The public contract information itself can be published as linked data. A specialized vocabulary, the Public Contracts Ontology, was designed for this purpose. Extractors and transformers for public contract datasets in various formats (HTML, CSV, XML) were developed to enable conversion into RDF format corresponding to the vocabulary. Moreover, an application for filing public contracts was implemented. It enables a contracting authority to manage RDF data about itself and its contracts, suppliers to the contracts, to-be-contracted products and services, and actual tenders proposed by bidders. It also provides matchmaking services for finding similar contracts and suitable suppliers for a given call for tenders based on their history, which is a useful feature for contracting authorities.

UnifiedViews: An ETL Framework for Sustainable RDF Data Processing

We present UnifiedViews, an Extract-Transform-Load (ETL) framework that allows users to define, execute, monitor, debug, schedule, and share ETL data processing tasks, which may employ custom plugins created by users. UnifiedViews differs from other ETL frameworks by natively supporting RDF data and ontologies. We are persuaded that UnifiedViews helps RDF/Linked Data consumers to address the problem of sustainable RDF data processing; we support such statement by introducing list of projects and other activities where UnifiedViews is successfully exploited.

Towards topic-based trust in social networks

The vast majority of applications consider generic notion of trust of a person to others, which is not restricted to any particular context or situation. Motivated by the financial scenario consuming data from distributed sources on the Web, we argue that we (as information consumers) cannot trust the information publishers or authors in general, however, only regarding the particular topics of the consumed data sources. To enable the so-called topic-based trust between users, we (1) propose a mechanism to persist the topic-based trust in a FOAF social network, (2) survey the topic hierarchies suitable for classifying the topics used in the trust model, and (3) propose an algorithm to compute trust with respect to the particular topic.

Linked Open Data for Legislative Domain - Ontology and Experimental Data

In this paper, we present an approach of publishing legislative content as Linked Open Data (LOD). LOD is a set of principles of publishing data on the Web in a machine-readable way so that links between different data sets, possibly published by different publishers, can be created. Therefore, LOD enable not only to publish data but also enrich with other existing data published according to the principles. We present what is the motivation for publishing legislation as LOD and what benefits can be gained. We then introduce a legislative ontology which builds on existing commonly used ontologies. We also show how we converted existing sources of legislation in Czech Republic to LOD.

Towards more secure web services - Exploiting and analysing XML signature security issues

The aim of this paper is to analyze the current security issues of XML Signature - a W3C Recommendation, which is used as a key part of the process of ensuring web services integrity. After introducing the necessary terminology, the problematic issues of the XML Signature W3C Recommendation are divided into several areas, inspected, and the solutions are described and compared. If an appropriate solution does not exist, or is not yet fully standardized, it is marked as an open problem and the solution is proposed.

Towards More Secure Web Services: Pitfalls of Various Approaches to XML Signature Verification Process

The goal of this paper is to formalize various processing approaches to the process of verification of the web services integrity and to show its vulnerability to many attacks. After introducing the necessary terminology, several processing approaches are particularized and its security drawbacks concerning notably XML Signature W3C Recommendation are divided into several areas, analyzed, and the solutions are described and compared. If the solution of the particular problem does not exist, or is not yet fully standardized, it is marked as an open problem and the solution is proposed.

Data Extraction Using NLP Techniques and Its Transformation to Linked Data

We present a system that extracts a knowledge base from raw unstructured texts that is designed as a set of entities and their relations and represented in an ontological framework. The extraction pipeline processes input texts by linguistically-aware tools and extracts entities and relations from their syntactic representation. Consequently, the extracted data is represented according to the Linked Data principles. The system is designed both domain and language independent and provides users with data for more intelligent search than full-text search. We present our first case study on processing Czech legal texts.

Linked Open Data for Public Procurement

Public procurement is an area that could largely benefit from linked open data technology. The respective use case of the LOD2 project covered several aspects of applying linked data on public contracts: ontological modeling of relevant concepts (Public Contracts Ontology), data extraction from existing semi-structured and structured sources, support for matchmaking the demand and supply on the procurement market, and aggregate analytics. The last two, end-user oriented, functionalities are framed by a specifically designed (prototype) web application.

A framework for storing and providing aggregated governmental linked open data

The paradigm of publishing governmental data is shifting from data trapped in the private data silos to open data, or even linked open data, bringing the information consumers (citizens, companies) unrestricted access to the data and enabling the agile information aggregation, which has up to now not been possible. Such information aggregation comes with inherent problems, such as provision of poor quality, inaccurate, irrelevant or fraudulent information. As a part of the OpenData.cz initiative and LOD2 project, we are developing a framework which will enable creation, maintenance, and usage of the data infrastructure formed by the linked open data. In this paper, we briefly describe our ongoing work on the framework --- the processes of (1) cleaning, linking, assessing the quality of data being stored and the processes of (2) providing aggregated views on the governmental linked open data.