Efficient similarity-based operations for data integration

Similarity-based operations, similarity join, similarity grouping, data integrationMagdeburg, Univ., Fak. für Informatik, Diss., 2004von Eike Schalleh

Group communications and database replication:techniques, issues and performance

Databases are an important part of today's IT infrastructure: both companies and state institutions rely on database systems to store most of their important data. As we are more and more dependent on database systems, securing this key facility is now a priority. Because of this, research on fault-tolerant database systems is of increasing importance. One way to ensure the fault-tolerance of a system is by replicating it. Replication is a natural way to deal with failures: if one copy is not available, we use another one. However implementing consistent replication is not easy. Database replication is hardly a new area of research: the first papers on the subject are more than twenty years old. Yet how to build an efficient, consistent replicated database is still an open research question. Recently, a new approach to solve this problem has been proposed. The idea is to rely on some communication infrastructure called group communications. This infrastructure offers some high-level primitives that can help in the design and the implementation of a replicated database. While promising, this approach to database replication is still in its infancy. This thesis focuses on group communication-based database replication and strives to give an overall understanding of this topic. This thesis has three major contributions. In the structural domain, it introduces a classification of replication techniques. In the qualitative domain, an analysis of fault-tolerance semantics is proposed. Finally, in the quantitative domain, a performance evaluation of group communication-based database replication is presented. The classification gives an overview of the different means to implement database replication. Techniques described in the literature are sorted using this classification. The classification highlights structural similarities of techniques originating from different communities (database community and distributed system community). For each category of the classification, we also analyse the requirements imposed on the database component and group communication primitives that are needed to enforce consistency. Group communication-based database replication implies building a system from two different components: a database system and a group communication system. Fault-tolerance is an end-to-end property: a system built from two components tends to be as fault-tolerant as the weakest component. The analysis of fault-tolerance semantics show what fault-tolerance guarantee is ensured by group communication based replication techniques. Additionally a new faulttolerance guarantee, group-safety, is proposed. Group-safety is better suited to group communication-based database replication. We also show that group-safe replication techniques can offer improved performance. Finally, the performance evaluation offers a quantitative view of group communication based replication techniques. The performance of group communication techniques and classical database replication techniques is compared. The way those different techniques react to different loads is explored. Some optimisation of group communication techniques are also described and their performance benefits evaluated

MDSSF: a federated architecture for product procurement

In the AEC (Architecture / Engineering / Construction) industry, large construction projects are tackled by consortia of companies and individuals, who work collaboratively for the duration of the project. The consortia include design teams, product suppliers, contractors and inspection teams who must collaborate and conform to predefined scheduling constraints and standards. These projects are unique, complex and involve many participants from a number of organisations. Construction projects require consortia to procure supplies such as building materials and furniture from product suppliers. In large AEC projects, procurement of products, services and construction materials is an important and time consuming activity. Materials are sourced on a global basis from a large number of suppliers. The scale of the purchases made in large projects show that their procurement is a non-trivial exercise. Therefore, consortia members or the contractors require access to a large body of information about products or material information to aid procurement decision making. Web based communication and network technologies play an increasingly important role in supporting collaboration in AEC projects. However collaborative working in the construction industry is still restricted by the current limitations of network and communication technologies and their system architectures which are usually client/server based. The construction industry has been examining how the advancements in distributed computing technologies such as the Grid computing can remove some of the existing limitations and enhance collaboration. This research investigated how the procurement challenges such as accessing up-to-date product information available from a large number of products suppliers in an integrated manner using standard means could be addressed. A novel solution to the procurement challenges in the form of a distributed information sharing architecture is presented. The architecture uses the concepts of federated databases such as distribution of data and autonomy of databases and couples it with Grid computing to facilitate information exchange in a collaborative, coherent and integrated way to address the product procurement challenges

Programming Languages and Systems

This open access book constitutes the proceedings of the 30th European Symposium on Programming, ESOP 2021, which was held during March 27 until April 1, 2021, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2021. The conference was planned to take place in Luxembourg and changed to an online format due to the COVID-19 pandemic. The 24 papers included in this volume were carefully reviewed and selected from 79 submissions. They deal with fundamental issues in the specification, design, analysis, and implementation of programming languages and systems

Multikonferenz Wirtschaftsinformatik (MKWI) 2016: Technische Universität Ilmenau, 09. - 11. März 2016; Band II

Übersicht der Teilkonferenzen Band II • eHealth as a Service – Innovationen für Prävention, Versorgung und Forschung • Einsatz von Unternehmenssoftware in der Lehre • Energieinformatik, Erneuerbare Energien und Neue Mobilität • Hedonische Informationssysteme • IKT-gestütztes betriebliches Umwelt- und Nachhaltigkeitsmanagement • Informationssysteme in der Finanzwirtschaft • IT- und Software-Produktmanagement in Internet-of-Things-basierten Infrastrukturen • IT-Beratung im Kontext digitaler Transformation • IT-Sicherheit für Kritische Infrastrukturen • Modellierung betrieblicher Informationssysteme – Konzeptuelle Modelle im Zeitalter der digitalisierten Wirtschaft (d!conomy) • Prescriptive Analytics in I

An infrastructure for context-dependent RDF data replication on mobile devices

Der im Rahmen dieser Arbeit vorgestellte Ansatz beschreibt die Erstellung einer technischen Infrastruktur, die selektiv RDF-Daten in Abhängigkeit der Informationsbedürfnisse und den unterschiedlichen Kontexten mobiler Nutzer auf ein mobiles Endgerät repliziert und diese somit in intelligenter Art und Weise unterstützt. Eine Zusammenführung kontextspezifischer Konzepte und semantischer Technologien stellt einen wesentlichen Bestandteil zur Verbesserung der mobilen Informationssuche dar und erhöht gleichzeitig die Präzision mobiler Informationsgewinnungsprozesse. Trotz des vorhandenen Potentials einer proaktiven, kontextabhängigen Replizierung von RDF-Daten, gestaltet sich die Verarbeitung auf mobilen Endgeräten schwierig. Die Gründe dafür liegen in den technischen und netzwerkspezifischen Beschränkungen, in der fehlenden Verarbeitungs- und Verwaltungsfunktionalität von ontologiebasierten Beschreibungsverfahren sowie in der Unzulänglichkeit bestehender Replikationsansätze, sich an verändernde Informationsbedürfnisse sowie an unterschiedliche technische, umgebungsspezifische und infrastrukturbezogene Eigenheiten anzupassen. Verstärkt wird diese Problematik durch das Fehlen ausdrucksstarker Beschreibungsverfahren zur Repräsentation kontextspezifischer Daten. Existierende Ansätze leiden dementsprechend unter der Verwendung proprietärer Datenformate, dem Einsatz serverabhängiger Applikationsinfrastrukturen sowie dem Unvermögen, kontextspezifische Daten auszutauschen. Dies äußert sich in Studien, welche die Berücksichtigung der Informationsbedürfnisse mobiler Nutzer als unzureichend einstuft und einen Großteil der benötigten Informationen als kontextrelevant auszeichnet. Obgleich Fortschritte bei der Adaption von semantischen Technologien und Beschreibungsverfahren zur kontextabhängigen Verarbeitung zu erkennen sind, bleibt eine auf semantische Technologien basierende, proaktive Replizierung von RDF-Daten auf mobile Endgeräte ein offenes Forschungsfeld. Die vorliegende Arbeit diskutiert Möglichkeiten zur Erweiterung der mobilen, kontextspezifischen Datenverarbeitung durch semantische Technologien und beinhaltet eine vergleichende Studie zur Leistungsfähigkeit aktueller mobiler RDF-Frameworks. Kernpunkt ist die formale Beschreibung eines abstrakten Modells zur effizienten Akquise, Repräsentation, Verwaltung und Verarbeitung von Kontextinformationen unter Berücksichtigung der technischen Gegebenheiten mobiler Informationssysteme. Ergänzt wird es durch die formale Spezifikation eines nebenläufigen, transaktionsbasierten Verarbeitungsmodells, welches Vollständigkeits- und Konsistenzbedingungen auf Daten- und Prozessebene berücksichtigt. Der praktische Nutzen des vorliegenden Ansatzes wird anhand typischer Informationsbedürfnisse eines Wissensarbeiters demonstriert. Der Ansatz reduziert Abhängigkeiten zu externen Systemen und ermöglicht Nutzern, unabhängig von zeitlichen, örtlichen und netzwerkspezifischen Gegebenheiten, auf die für sie relevanten Daten zuzugreifen und diese zu verarbeiten. Durch die lokale Verarbeitung kontextbezogener Daten wird sowohl die Privatssphäre des Nutzers gewahrt als auch sicherheitsrelevanten Aspekten Rechnung getragen.This work describes an infrastructure for the selective RDF data replication to mobile devices while considering current and future information needs of mobile users and the different contexts they are operating in. It presents a novel approach in synthesizing context-aware computing concepts with semantic technologies and distributed transaction management concepts for intelligently assisting mobile users while enhancing mobile information seeking behavior and increasing the precision of mobile information retrieval processes. Despite the huge potential of a proactive, context-dependent replication of RDF data, such data can not be efficiently processed on mobile devices due to (i) technical limitations and network-related constraints, (ii) missing processing and management capabilities of ontology-based description frameworks, (iii) the inability of traditional data replication strategies to adapt to changing user information needs and to consider technical, environmental, and infrastructural restrictions of mobile operating systems, and (iv) the dynamic and emergent nature of context, which requires flexible and extensible description frameworks that allow for elaborating on the semantics of contextual constellations as well as on the relationships that exist between them. As a consequence, existing approaches suffer from the deployment of proprietary data formats, server-dependent application infrastructures, and the inability to share and exchange contextual information across system borders. Moreover, results of recently conducted studies reveal that mobile users find their information needs inadequately addressed, where a large share can be attributed as context or context-relevant. Although progress has been made in applying semantic technologies, concepts, and languages to the domain of context-aware computing, a synthesis of those fields for the proactive provision of RDF data replicas on mobile devices remains an open research issue. This work discusses possible fields where context-aware computing can be enhanced using technologies, languages, and concepts from the Semantic Web and contains a comparative study about the performance of current mobile RDF frameworks in replication-specific tasks. The main contribution of this thesis is a formal description of an abstract model that allows for an efficient acquisition, representation, management, and processing of contextual information while taking into account the peculiarities and operating environments of mobile information systems. It is complemented by a formal specification of a concurrently operating transaction-based processing model that considers completeness and consistency requirements on data and process level. We demonstrate the practicability of the presented approach trough a prototypical implementation of context and data providers that satisfy typical information needs of a mobile knowledge worker. As a consequence, dependencies to external systems are reduced and users are equipped with relevant information that adheres to their information needs anywhere and at any time, independent of any network-related constraints. Since context-relevant data are processed directly on a mobile device, security and privacy issues are preserved

LIPIcs, Volume 251, ITCS 2023, Complete Volume

LIPIcs, Volume 251, ITCS 2023, Complete Volum