Download Free The Management Of Replication In A Distributed System Book in PDF and EPUB Free Download. You can read online The Management Of Replication In A Distributed System and write the review.

Replication Techniques in Distributed Systems organizes and surveys the spectrum of replication protocols and systems that achieve high availability by replicating entities in failure-prone distributed computing environments. The entities discussed in this book vary from passive untyped data objects, to typed and complex objects, to processes and messages. Replication Techniques in Distributed Systems contains definitions and introductory material suitable for a beginner, theoretical foundations and algorithms, an annotated bibliography of commercial and experimental prototype systems, as well as short guides to recommended further readings in specialized subtopics. This book can be used as recommended or required reading in graduate courses in academia, as well as a handbook for designers and implementors of systems that must deal with replication issues in distributed systems.
Replication is a topic of interest in the distributed computing, distributed systems, and database communities. Although these communities have traditionally looked at replication from different viewpoints and with different goals (e.g., performance versus fault tolerance), recent developments have led to a convergence of these different goals. The objective of this state-of-the-art survey is not to speculate about the future of replication, but rather to understand the present, to make an assessment of approximately 30 years of research on replication, and to present a comprehensive view of the achievements made during this period of time. This book is the outcome of the seminar entitled A 30-Year Perspective on Replication, which was held at Monte Verità, Ascona, Switzerland, in November 2007. The book is organized in 13 self-contained chapters written by most of the people who have contributed to developing state-of-the-art replication techniques. It presents a comprehensive view of existing solutions, from a theoretical as well as from a practical point of view. It covers replication of processes/objects and of databases; replication for fault tolerance and replication for performance - benign faults and malicious (Byzantine) faults - thus forming a basis for both professionals and students of distributed computing, distributed systems, and databases.
This third edition of a classic textbook can be used to teach at the senior undergraduate and graduate levels. The material concentrates on fundamental theories as well as techniques and algorithms. The advent of the Internet and the World Wide Web, and, more recently, the emergence of cloud computing and streaming data applications, has forced a renewal of interest in distributed and parallel data management, while, at the same time, requiring a rethinking of some of the traditional techniques. This book covers the breadth and depth of this re-emerging field. The coverage consists of two parts. The first part discusses the fundamental principles of distributed data management and includes distribution design, data integration, distributed query processing and optimization, distributed transaction management, and replication. The second part focuses on more advanced topics and includes discussion of parallel database systems, distributed object management, peer-to-peer data management, web data management, data stream systems, and cloud computing. New in this Edition: • New chapters, covering database replication, database integration, multidatabase query processing, peer-to-peer data management, and web data management. • Coverage of emerging topics such as data streams and cloud computing • Extensive revisions and updates based on years of class testing and feedback Ancillary teaching materials are available.
Despite the growing interest in Real-Time Database Systems, there is no single book that acts as a reference to academics, professionals, and practitioners who wish to understand the issues involved in the design and development of RTDBS. Real-Time Database Systems: Issues and Applications fulfills this need. This book presents the spectrum of issues that may arise in various real-time database applications, the available solutions and technologies that may be used to address these issues, and the open problems that need to be tackled in the future. With rapid advances in this area, several concepts have been proposed without a widely accepted consensus on their definitions and implications. To address this need, the first chapter is an introduction to the key RTDBS concepts and definitions, which is followed by a survey of the state of the art in RTDBS research and practice. The remainder of the book consists of four sections: models and paradigms, applications and benchmarks, scheduling and concurrency control, and experimental systems. The chapters in each section are contributed by experts in the respective areas. Real-Time Database Systems: Issues and Applications is primarily intended for practicing engineers and researchers working in the growing area of real-time database systems. For practitioners, the book will provide a much needed bridge for technology transfer and continued education. For researchers, this book will provide a comprehensive reference for well-established results. This book can also be used in a senior or graduate level course on real-time systems, real-time database systems, and database systems or closely related courses.
Database replication is widely used for fault-tolerance, scalability and performance. The failure of one database replica does not stop the system from working as available replicas can take over the tasks of the failed replica. Scalability can be achieved by distributing the load across all replicas, and adding new replicas should the load increase. Finally, database replication can provide fast local access, even if clients are geographically distributed clients, if data copies are located close to clients. Despite its advantages, replication is not a straightforward technique to apply, and there are many hurdles to overcome. At the forefront is replica control: assuring that data copies remain consistent when updates occur. There exist many alternatives in regard to where updates can occur and when changes are propagated to data copies, how changes are applied, where the replication tool is located, etc. A particular challenge is to combine replica control with transaction management as it requires several operations to be treated as a single logical unit, and it provides atomicity, consistency, isolation and durability across the replicated system. The book provides a categorization of replica control mechanisms, presents several replica and concurrency control mechanisms in detail, and discusses many of the issues that arise when such solutions need to be implemented within or on top of relational database systems. Furthermore, the book presents the tasks that are needed to build a fault-tolerant replication solution, provides an overview of load-balancing strategies that allow load to be equally distributed across all replicas, and introduces the concept of self-provisioning that allows the replicated system to dynamically decide on the number of replicas that are needed to handle the current load. As performance evaluation is a crucial aspect when developing a replication tool, the book presents an analytical model of the scalability potential of various replication solution. For readers that are only interested in getting a good overview of the challenges of database replication and the general mechanisms of how to implement replication solutions, we recommend to read Chapters 1 to 4. For readers that want to get a more complete picture and a discussion of advanced issues, we further recommend the Chapters 5, 8, 9 and 10. Finally, Chapters 6 and 7 are of interest for those who want get familiar with thorough algorithm design and correctness reasoning. Table of Contents: Overview / 1-Copy-Equivalence and Consistency / Basic Protocols / Replication Architecture / The Scalability of Replication / Eager Replication and 1-Copy-Serializability / 1-Copy-Snapshot Isolation / Lazy Replication / Self-Configuration and Elasticity / Other Aspects of Replication
In traditional service architectures that follow the service statelessness principle, the state is primarily held in the data tier. Here, service operators utilize tailored storage solutions to guarantee the required availability; even though failures can occur at any time. This centralized approach to store and process an application’s state in the data tier implies that outages of the entire tier cannot be tolerated. An alternative approach, which is in focus of this thesis, is to decentralize the processing of state information and to use more stateful components in the early tiers. The possibility to tolerate a temporary outage of an entire tier implies that the application’s state can be manipulated by the remaining tiers without waiting for approval from the unavailable tier. This setup requires multi-leader replication, where every replica can accept writes and forwards the resulting changes to the other replicas. This thesis explores the feasibility of using multi-leader replication to store and process state in a decentralized manner across multiple tiers. To this end, two replication mechanisms, namely Conflict-free Replicated Data Types and Operational Transformation, are under particular investigation. We use and extend both mechanism to demonstrate that the aforementioned decentralization is worth considering when designing a service architecture. The challenges that arise when following our approach go back to fundamental impossibility results in distributed systems research, i.e. the impossibility to achieve a fault-tolerant consensus mechanism in asynchronous systems and the inevitable trade-off between availability and consistency in the presence of failures. With this thesis, we contribute to close the exposed gaps of both results by providing usable alternatives for standard IT services. We exemplify the feasibility of our alternatives with a fully distributed IMAP service and a programming library that provides the necessary extension to utilize our approach in a variety of web-based applications. All contributions of this thesis are based on both theory and practice. In particular, all extensions to the existing multi-leader replication mechanisms were proven to satisfy the necessary properties. Moreover, those extensions were also implemented as prototypical applications and evaluated against the corresponding de facto standard software from the industry. Basierend auf dem “service statelessness principle” ist es üblich, Softwaredienste so zu entwerfen, dass der Zustand des Dienstes primär in einer gekapselten Datenschicht verarbeitet wird. Innerhalb der Datenschicht werden spezielle Lösungen verwendet, um die Verfügbarkeit der Daten sicherzustellen. Dieser zentralisierte Ansatz hat zur Folge, dass ein Ausfall oder eine temporäre Nichtverfügbarkeit der gesamten Datenschicht zwangsweise zur Nichtverfügbarkeit des gesamten Dienstes führt. Ein alternativer Ansatz, welcher in dieser Arbeit erforscht wird, ist die dezentralisierte Speicherung und Verarbeitung der Daten in den darüberliegenden Softwareschichten. Um in diesem Ansatz einen Ausfall der gesamten Datenschicht zu kompensieren, ist es zwingend notwendig, dass die verbleibenden Schichten die eingehenden Anfragen ohne die Bestätigung durch die Datenschicht beantworten können. Hierfür wird eine Replikationsarchitektur benötigt, in der jedes Replikat die Anfragen direkt beantworten kann; die so genannte “multi-leader replication”. In dieser Arbeit werden diese Replikationsarchitekturen verwendet, um den Zustand und die Daten eines Dienstes zu dezentralisieren und über mehrere Schichten zu replizieren. Hierbei werden zwei Mechanismen detaillierter betrachtet: “Conflict-free Replicated Data Types” und “Operational Transformation”. Anschließend werden beide Mechanismen erweitert und hinsichtlich der Verwendbarkeit für den beschriebenen Ansatz geprüft. Als Ergebnis dieser Arbeit wird gezeigt, dass ein dezentralisierter Ansatz mit den vorgestellten Mechanismen in Betracht gezogen werden kann. Die Herausforderungen, die bei der Anwendung dieses Ansatzes entstehen, basieren auf nachweislich unlösbaren Problemen aus der Forschung von Verteilten Systemen. Dazu gehört die Unlösbarkeit von Konsensus und die unausweichliche Abwägung zwischen Verfügbarkeit und Konsistenz in einem verteilten System mit Ausfällen. Diese Arbeit trägt dazu bei, die entstehenden Lücken, welche aus diesen fundamentalen Ergebnissen resultieren, zu schließen und die vorgeschlagenen Lösungen für reale IT Dienste anwendbar zu machen. Dieses wird anhand eines dezentralen IMAP Dienstes und einer Programmierbibliothek für Webanwendungen verdeutlicht. Alle Bestandteile dieser Doktorarbeit verbinden Theorie und Praxis. Alle vorgeschlagenen Erweiterungen für bestehende Replikationssysteme werden in formalen Modellen verifiziert und prototypisch implementiert. Die Implementierungen werden außerdem mit vergleichbarer Standardsoftware, welche dem heutigen Stand der Technik entspricht, in praktischen Experimenten evaluiert.
Any organization that uses the Oracle relational database management system (RDBMS) these days needs to use multiple databases. There are many reasons to use more than a single database in a distributed database system: Different databases may be associated with particular business functions, such as manufacturing or human resources. Databases may be aligned with geographical boundaries, such as a behemoth database at a headquarters site and smaller databases at regional offices. Two different databases may be required to access the same data in different ways, such as an order entry database whose transactions are aggregated and analyzed in a data warehouse. A busy Internet commerce site may create multiple copies of the same database to attain horizontal scalability. A copy of a production database may be created to serve as a development test bed. Tunability Platform autonomy Fault tolerance Scalability Location transparency Site autonomy Introduction to Distributed Database Systems SQL*Net and Net8 Configuration and Administration Distributed Database Security Designing the Distributed System Oracle's Distributed System Implementation Sample Configurations 8. Engineering Considerations Oracle Replication Architecture Advanced Replication Option Installation Basic Replication Multi-Master Replication Updateable Snapshots Procedural Replication Conflict Avoidance and Resolution Techniques In a distributed database environment, data in two or more databases is accessible as if it were in a single database. Usually, the different databases are on different servers, which may be located at the same site or a continent away. Communication between the servers takes place via SQL*Net (for Oracle7) or Net8 (for Oracle8). Distributed database environments offer a number of benefits over single- database systems, including: This book describes how you can use multiple databases and the distributed features of Oracle to best advantage. It covers: Table of contents: Part I: The Distributed System Part II: Replication Part III: Appendixes Appendix A: Built-in Packages for Distributed Systems Appendix B: Scripts.