Orientador: Claudia Maria Bauzer Medeiros / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-23T23:06:49Z (GMT). No. of bitstreams: 1 Koga_IvoKenji_D.pdf: 2109870 bytes, checksum: 7ac5400b2e71be3e15b3bdf5504e3adf (MD5) Previous issue date: 2013 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The complete abstract is available with the full electronic document. / Doutorado / Ciência da Computação / Doutor em Ciência da Computação

Owing to the explosive growth of data driven by e-commerce, social media, and mobile apps, data outsourcing and integration have become two popular Internet services. These services involve one or more data owners (DOs), many requesting clients, and a service provider (SP). The DOs outsource/synchronize their data to the SP, and the SP will provide query services to the requesting clients on behalf of DOs. However, as a third-party server, the SP might alter (leave out or forge) the outsourced/integrated data and query results, intentionally or not. To address this trustworthy issue, the SP is expected to deliver their services in an authenticatable manner, so that the correctness of the service results can be verified by the clients. Unfortunately, existing work on query authentication cannot preserve the privacy of the data being queried. Furthermore, almost all previous studies assume only a single data source/owner, while data integration services usually combine data from multiple sources. In this dissertation, we take the first step to study the authentication of location-based queries with confidentiality and investigate authenticated online data integration services. Cost models, security analysis, and experimental results consistently show the effectiveness and robustness of our proposed schemes under various system settings and query workloads.

Submitted in partial fulfillment of the requirement of the degree Magister Technologiae: Information Technology, Durban University of Technology, Durban, South Africa, 2015. / The research reported in this dissertation focuses on seamless data sharing in e-government space because of the intrinsic complexity, disparity and heterogeneity of government information systems as well as the need to improve government service delivery. The often observed bureaucracy in government processes, especially when verifying information, coupled with the high interdependency of government departments and diversity in government operations has made it difficult to improve government service delivery efficiency. These challenges raise the need to find better ways to seamlessly share data between government to citizens, government to businesses, government to suppliers and government to public institutions. Obviously, efficient automatic data sharing is an important phenomenon that contributes to improvements in communication, collaboration, interaction and efficiency in the service delivery process because it reduces information verification time and improves reliability of information. The general applications of data sharing systems become perceptible in institutions such as banks and government establishments where information verification is highly necessary in the process of service delivery. Data sharing usually occurs between a data holder and a data requester when copies of authorized data are transported from the source databases to the requester. This data sharing process should guarantee a high level of privacy because of the confidential nature of certain data. A data integration gateway (DIG) is being proposed in this research as a methodological solution to seamlessly share data in e-government space, using Hippocratic database principles to enforce data privacy. The DIG system is a centralized web application that utilizes a lightweight database within the government data centre to hold information on data contracts, data sources, connection strings and data destinations. The data sharing policies are stated as contracts and once indentures on how to share data are established between different data publishers, it is possible to ensure a seamless integration of data from different sources using the DIG application being proposed in this dissertation. The application is malleable to support the sharing of publisher data that are stored in any kind of database. The proposed DIG application promises to reduce costs of system maintenance and improve service delivery efficiency without any change to the existing hardware infrastructure and information systems residing within different government departments.

Data interoperability between computer-aided design (CAD) systems remains a major obstacle in the information integration and exchange in a collaborative engineering environment. The standards for CAD data exchange have remained largely restricted to geometric representations, causing the design intent portrayed through construction history, features, parameters, and constraints to be discarded in the exchange process. In this thesis, an ontology-based framework is proposed to allow for the full exchange of semantic feature data. A hybrid ontology approach is proposed, where a shared base ontology is used to convey the concepts that are common amongst different CAD systems, while local ontologies are used to represent the feature libraries of individual CAD systems as combinations of these shared concepts. A three-branch CAD feature model is constructed to reduce ambiguity in the construction of local ontology feature data. Boundary representation (B-Rep) data corresponding to the output of the feature operation is incorporated into the feature data to enhance data exchange. The Ontology Web Language (OWL) is used to construct a shared base ontology and a small feature library, which allows the use of existing ontology reasoning tools to infer new relationships and information between heterogeneous data. A combination of OWL and SWRL (Semantic Web Rule Language) rules are developed to allow a feature from an arbitrary source system expressed via the shared base ontology to be automatically classified and translated into the target system. These rules relate input parameters and reference types to expected B-Rep objects, allowing classification even when feature definitions vary or when little is known about the source system. In cases when the source system is well known, this approach also permits direct translation rules to be implemented. With such a flexible framework, a neutral feature exchange format could be developed.