Showing papers by "Alessandra Mileo published in 2013"

StreamRule: a nonmonotonic stream reasoning system for the semantic web

Abstract: Stream reasoning is an emerging research field focused on dynamic processing and continuous reasoning over huge volumes of streaming data. Finding the right trade-off between scalability and expressivity is a key challenge in this area. In this paper, we want to provide a baseline for exploring the applicability of complex reasoning to the Web of Data based on a solution that combines results and approaches from database research, stream processing, and nonmonotonic logic programming.

Secure Manipulation of Linked Data

Abstract: When it comes to publishing data on the web, the level of access control required (if any) is highly dependent on the type of content exposed. Up until now RDF data publishers have focused on exposing and linking public data. With the advent of SPARQL 1.1, the linked data infrastructure can be used, not only as a means of publishing open data but also, as a general mechanism for managing distributed graph data. However, such a decentralised architecture brings with it a number of additional challenges with respect to both data security and integrity. In this paper, we propose a general authorisation framework that can be used to deliver dynamic query results based on user credentials and to cater for the secure manipulation of linked data. Specifically we describe how graph patterns, propagation rules, conflict resolution policies and integrity constraints can together be used to specify and enforce consistent access control policies.

Triplifying Wikipedia's tables

Abstract: We are currently investigating methods to triplify the content of Wikipedia's tables. We propose that existing knowledge-bases can be leveraged to semi-automatically extract high-quality facts (in the form of RDF triples) from tables embedded in Wikipedia articles (henceforth called "Wikitables"). We present a survey of Wikitables and their content in a recent dump of Wikipedia. We then discuss some ongoing work on using DBpedia to mine novel RDF triples from these tables: we present methods that automatically extract 24.4 million raw triples from the Wikitables at an estimated precision of 52.2%. We believe this precision can be (greatly) improved through machine learning methods and sketch ideas for features that should help classify (in)correct triples.

DRETa: extracting RDF from wikitables

Abstract: Tables are widely used in Wikipedia articles to display relational information - they are inherently concise and information rich. However, aside from info-boxe s, there are no automatic methods to exploit the integrated content of these tables. We thus present DRETa: a tool that uses DBpedia as a reference knowledge-base to extract RDF triples from generic Wikipedia tables.

Update Semantics for Interoperability among XML, RDF and RDB A Case Study of Semantic Presence in CISCO's Unified Presence Systems

Abstract: XSPARQL is a transformation and querying language that provides an integrated access over heterogeneous data sources on the fly. It is an extension of XQuery which supports a subset of SPARQL and SQL to provide unified access over XML, RDF and RDB formats. In practical applications, data integration does not only require the integrated access over distributed heterogeneous data sources, but also the update of underlying data.

Applying DAC Principles to the RDF Graph Data Model

Abstract: In this paper we examine how Discretionary Access Control principles, that have been successfully applied to relational and XML data, can be applied to the Resource Description Framework (RDF) graph data model. The objective being to provide a baseline for the specification of a general authorisation framework for the RDF data model. Towards this end we provide a summary of access control requirements for graph data structures, based on the different characteristics of graph models compared to relational and tree data models. We subsequently focus on the RDF data model and identify a list of access rights based on SPARQL query operations; propose a layered approach to authorisation derivation based on the graph structure and RDFSchema; and demonstrate how SQL GRANT and REVOKE commands can be adapted to cater for delegation of privileges in SPARQL.

XSPARQL-Viz: A Mashup-Based Visual Query Editor for XSPARQL

Abstract: XSPARQL is a query language which facilitates query, integration and transformation between XML and RDF data formats. Although XSPARQL supports semantic data integration by providing uniform access over XML and RDF, but it requires users to be familiar with both of its underlying query languages (e.g XQuery and SPARQL). In this system demo, we show how mashup-based techniques can be used for auto generation and execution of XSPARQL queries. XSPARQL-Viz provides an easy to use drag and drop visual query editor, which supports novice users in designing complex mappings between XML and RDF and based on these mappings auto generates and executes XSPARQL queries. Results can also be visualised as a graph, table or list.

Semantically Interlinked Notification System for Ubiquitous Presence Management

Abstract: Presence based notification systems play a pivotal role in any collaborative working environment by providing near real time information about the status, locality and presence of the collaborators. Instant Messaging (IM) tools provide a simple low cost solution to support communication and collaboration in the working environment. With the wide adoption of smart phones, there is an increasing trend of using IM clients on mobile devices for exchanging and managing presence information. However, in modern organisations the use of collaborative tools is not limited only to IMs, but various other tools are also used, such as project management tools, meeting agenda, calendar and alike. In this paper we design, develop and implement an agile platform for ubiquitous presence management that relies on semantically interlinked vocabularies, existing information extraction tools for semantic enhancement of heterogeneous enterprise collaborative tools, continuous query processing for semantic integration and event detection in dynamic environment, and semantic transformation via query language for event-triggered notification actions based on the users context. We showcase our proposed solution by demonstrating a real world scenario for Cisco’s Unified Presence System and we evaluate our solution in terms of requirements for Ubiquitous Presence Management System (UPMS) compared to related solutions, and overhead of each additional processing step, namely semantic transformation, continuous query processing and notification.