ODE-SWS: A Semantic Web Service Development Environment

Web Services (WS) are software modules that perform operations that are network-accessible through XML messaging. Web Services in the Semantic Web, that is, Semantic Web Services (SWS), should describe semantically their structure and capabilities to enable its automatic discovery, invocation and composition. In this work we present a development environment to design SWS in a language-independent manner. This environment is based on a framework that defines an ontology set to characterize how a SWS should be specified. The core ontology of this framework describes the SWS problem-solving behaviour and enables the SWS design at a conceptual level. Considering this framework, the SWS development environment is composed of (1) a graphical interface, in which the conceptual design of SWSs is performed, and (2) a tool set, which instantiates the framework ontologies according to the graphical model created by the user, verifies the completeness and consistency of the SWS through instance evaluation, and translates the SWS conceptual model description into SWS (and WS) languages, such as DAML-S, WSDL or UDDI. This tool set is integrated in the WebODE ontology engineering workbench in order to take advantage of its reasoning and ontology translation capabilities

EP-RDF: sistema para armazenamento e recuperação de imagens baseado em ontologia

A web semântica representa a evolução da web atual. Ela fornece estruturas e possibilita a extração de significados dos conteúdos das páginas web, criando um ambiente onde agente de software e usuários possam trabalhar de forma cooperativa (BERNERS-LEE, 2001). Vários trabalhos vêm sendo desenvolvidos para criar um ambiente propício à existência de uma web com significado. Berners-Lee propôs uma arquitetura para a web semântica composta de três camadas: estrutural (permite a sistematização das informações), ontológica (fornece um conjunto de regras que define hierarquia, relacionamentos e restrições entre termos) e lógica (define um conjunto de regras de inferências). O objetivo do presente trabalho é demonstrar algumas das etapas de desenvolvimento da ferramenta de busca EP RDF Images, que permite a organização e a recuperação de imagens a partir da definição de uma ontologia para o domínio “imagens de instituições de ensino”, e um estudo comparativo com alguns mecanismos de buscas disponíveis na web (google.com e gettyimages.com).II Workshop de Ingeniería de Software y Bases de Datos (WISBD)Red de Universidades con Carreras en Informática (RedUNCI

EP-RDF: sistema para armazenamento e recuperação de imagens baseado em ontologia

A web semântica representa a evolução da web atual. Ela fornece estruturas e possibilita a extração de significados dos conteúdos das páginas web, criando um ambiente onde agente de software e usuários possam trabalhar de forma cooperativa (BERNERS-LEE, 2001). Vários trabalhos vêm sendo desenvolvidos para criar um ambiente propício à existência de uma web com significado. Berners-Lee propôs uma arquitetura para a web semântica composta de três camadas: estrutural (permite a sistematização das informações), ontológica (fornece um conjunto de regras que define hierarquia, relacionamentos e restrições entre termos) e lógica (define um conjunto de regras de inferências). O objetivo do presente trabalho é demonstrar algumas das etapas de desenvolvimento da ferramenta de busca EP RDF Images, que permite a organização e a recuperação de imagens a partir da definição de uma ontologia para o domínio “imagens de instituições de ensino”, e um estudo comparativo com alguns mecanismos de buscas disponíveis na web (google.com e gettyimages.com).II Workshop de Ingeniería de Software y Bases de Datos (WISBD)Red de Universidades con Carreras en Informática (RedUNCI

Extracting Temporal Expressions from Unstructured Open Resources

AETAS is an end-to-end system with SOA approach that retrieves plain text data from web and blog news and represents and stores them in RDF, with a special focus on their temporal dimension. The system allows users to acquire, browse and query Linked Data obtained from unstructured sources

Semantos : a semantically smart information query language

Enterprise Information Integration (EII) is rapidly becoming one of the pillars of modern corporate information systems. Given the spread and diversity of information sources in an enterprise, it has become increasingly difficult for decision makers to have access to relevant and accurate information at the opportune time. It has therefore become critical to seamlessly integrate the diverse information stores found in an organization into a single coherent data source. This is the job of EII and one of the key components to making it work is harnessing the implied meaning or semantics hidden within data sources. Modern EII systems are capable of harnessing semantic information and ontologies to make integration across data stores possible. These systems do not, however, allow a consumer of the integration service to build queries with semantic meaning. This is due to the fact that most EII systems make use of XQuery, SQL, or both, as query languages, neither of which has the capability to build semantically rich queries. In this thesis Semantos (from the Greek word sema for “sign or token”) is proposed as a viable alternative: an information query language based in XML, which is capable of exploiting ontologies, enabling consumers to build semantically enriched queries. An exploration is made into the characteristics or requirements that Semantos needs to satisfy as a semantically smart information query language. From these requirements we design and develop a software implementation. The benefit of Semantos is that it possesses a query structure that allows automated processes to decompose and restructure the queries without human intervention. We demonstrate the applicability of Semantos using two realistic examples: a query enhancement- and a query translation service. Both expound the ability of a Semantos query to be manipulated by automated services to achieve Information Integration goals.Dissertation (MSc)--University of Pretoria, 2009.Computer Scienceunrestricte

Data Integration on the (Semantic) Web with Rules and Rich Unification

For the last decade a multitude of new data formats for the World Wide Web have been developed, and a huge amount of heterogeneous semi-structured data is flourishing online. With the ever increasing number of documents on the Web, rules have been identified as the means of choice for reasoning about this data, transforming and integrating it. Query languages such as SPARQL and rule languages such as Xcerpt use compound queries that are matched or unified with semi-structured data. This notion of unification is different from the one that is known from logic programming engines in that it (i) provides constructs that allow queries to be incomplete in several ways (ii) in that variables may have different types, (iii) in that it results in sets of substitutions for the variables in the query instead of a single substitution and (iv) in that subsumption between queries is much harder to decide than in logic programming. This thesis abstracts from Xcerpt query term simulation, SPARQL graph pattern matching and XPath XML document matching, and shows that all of them can be considered as a form of rich unification. Given a set of mappings between substitution sets of different languages, this abstraction opens up the possibility for format-versatile querying, i.e. combination of queries in different formats, or transformation of one format into another format within a single rule. To show the superiority of this approach, this thesis introduces an extension of Xcerpt called Xcrdf, and describes use-cases for the combined querying and integration of RDF and XML data. With XML being the predominant Web format, and RDF the predominant Semantic Web format, Xcrdf extends Xcerpt by a set of RDF query terms and construct terms, including query primitives for RDF containers collections and reifications. Moreover, Xcrdf includes an RDF path query language called RPL that is more expressive than previously proposed polynomial-time RDF path query languages, but can still be evaluated in polynomial time combined complexity. Besides the introduction of this framework for data integration based on rich unification, this thesis extends the theoretical knowledge about Xcerpt in several ways: We show that Xcerpt simulation unification is decidable, and give complexity bounds for subsumption in several fragments of Xcerpt query terms. The proof is based on a set of subsumption monotone query term transformations, and is only feasible because of the injectivity requirement on subterms of Xcerpt queries. The proof gives rise to an algorithm for deciding Xcerpt query term simulation. Moreover, we give a semantics to locally and weakly stratified Xcerpt programs, but this semantics is applicable not only to Xcerpt, but to any rule language with rich unification, including multi-rule SPARQL programs. Finally, we show how Xcerpt grouping stratification can be reduced to Xcerpt negation stratification, thereby also introducing the notion of local grouping stratification and weak grouping stratification

Formal aspects of querying RDF databases

We study formal aspects of querying databases containing RDF data. We present a formal definition of a query language for RDF and compare it with other proposals. Our language is intended to make it easy to formalize and prove results about its properties. We study novel features of query languages derived from the presence of blank nodes and reification. Finally we provide complexity results for query processing, static optimization of queries, and redundancy elimination in answers