database Management systems.(DBMS) are used by software applications, to store, manipulate, and retrieve large sets of data. However, the requirements of current softwaresystems.pose various challenges to established...
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ISBN:
(纸本)9781450326278
database Management systems.(DBMS) are used by software applications, to store, manipulate, and retrieve large sets of data. However, the requirements of current softwaresystems.pose various challenges to established DBMS. First, most softwaresystems.organize their data by means of objects rather than relations leading to increased maintenance, redundancy, and transformation overhead when persisting objects to relational databases. second, complex objects are separated into several objects resulting in Object Schizophrenia and hard to persist distributed State. Last but not least, current softwaresystems.have to cope with increased complexity and changes. These challenges have lead to a general paradigm shift in the development of softwaresystems. Unfortunately, classical DBMS will become intractable, if they are not adapted to the new requirements imposed by these softwaresystems. As a result, we propose an extension of DBMS with roles to represent complex objects within a relational database and support the flexibility required by current softwaresystems. To achieve this goal, we introduces RSQL, an extension to SQL with the concept of objects playing roles when interacting with other objects. Additionally, we present a formal model for the logical representation of roles in the extended DBMS.
Binary optimization models for the design of distributed, fault-tolerant computing systems.are considered, with a focus on the task allocation and file assignment modeling schema proposed by J. Bannister and K. Trived...
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An approach is presented that will allow database applications to increase availability in the face of network partitions and other communications failures, by permitting a controlled amount of nonserializable databas...
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ISBN:
(纸本)0818606908
An approach is presented that will allow database applications to increase availability in the face of network partitions and other communications failures, by permitting a controlled amount of nonserializable database activity. The underlying replicated database substrate ensures mutual consistency, without serializability, by timestamping all updates issued by database interactions. Compensating actions, triggered by exception conditions in the database, attempt to correct problems arising from nonserializable execution or notify human agents to investigate and correct the problem. Probabilistic concurrency control uses a controlled amount of inter-site synchronization to reduce the likelihood of nonserializable execution and the burden of compensation, at the cost of slightly reduced availability. This approach, illustrated by means of examples, allows application designers to tailor the system to achieve any desired balance between availability and consistency.
This conference proceedings contains 19 papers. The following topics are dealt with: recovery;replication;network architecture;reliable communication;performance analysis;evaluation and modeling;and simulation and tes...
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This conference proceedings contains 19 papers. The following topics are dealt with: recovery;replication;network architecture;reliable communication;performance analysis;evaluation and modeling;and simulation and testing.
The design and implementation of an experimental fault-tolerant distributeddatabase management system is described. The system provides a logically integrated view of data with distribution transparency and a control...
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ISBN:
(纸本)0818608757
The design and implementation of an experimental fault-tolerant distributeddatabase management system is described. The system provides a logically integrated view of data with distribution transparency and a controlled data replication. A commitment protocol used to guarantee atomicity of update operations is discussed. Efficient algorithms used to recover a site from a failure and restore data consistency are described. Recovery can be interleaved with the processing of regular database transactions and does not seriously limit the availability of data. The proposed solutions to the problems of fault recovery are designed to take advantage of the properties of a high-bandwidth local area network.
The proposed coordinator log transaction execution protocol centralizes logging on a per-transaction basis and exploits piggybacking to provide the semantics of a distributed atomic commit without the associated costs...
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The proposed coordinator log transaction execution protocol centralizes logging on a per-transaction basis and exploits piggybacking to provide the semantics of a distributed atomic commit without the associated costs. This protocol eliminates two rounds of messages (one phase) from the presumed commit protocol and dramatically reduces the number of log forces needed for distributed atomic commit. The authors compare the coordinator log transaction execution protocol with existing protocols, describe when it is desirable, and discuss how it affects the write-ahead log protocol and the database crash recovery algorithm.
As softwaredistributed Shared Memory(DSM) systems.become attractive on larger clusters, the focus of attention moves toward improving the reliability of systems. In this paper, we propose a lightweight logging scheme...
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ISBN:
(纸本)0769520693
As softwaredistributed Shared Memory(DSM) systems.become attractive on larger clusters, the focus of attention moves toward improving the reliability of systems. In this paper, we propose a lightweight logging scheme, called remote logging, and a recovery protocol for home-based DSM. Remote logging stores coherence-related data to the volatile memory of a remote node. The logging overhead can be moderated with high-speed system area network and user-level DMA operations supported by modern communication protocols. Remote logging tolerates multiple failures if the backup nodes of failed nodes are alive. It makes the reliability of DSM grow much higher. Experimental results show that our fault-tolerant DSM has low overhead compared to conventional stable logging and it can be effectively recovered from some concurrent failures.
distributed synchronization for data sharing is discussed, and the design of a distributed lock manager for the Camelot transaction facility is presented. The lock manager is a component of a proposed implementation o...
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distributed synchronization for data sharing is discussed, and the design of a distributed lock manager for the Camelot transaction facility is presented. The lock manager is a component of a proposed implementation of data sharing in the Camelot environment. A number of experiments that demonstrate the correct operation of the lock manager are reported and its performance is described. The performance metrics indicate that distributed lock management should not reduce the feasibility of data sharing in this environment. The similarity between the caching and synchronization strategies appropriate for locks and data suggests that protocols developed for distributed locks will be applicable to data sharing.
One property that makes failures difficult to handle in programs is that the actions of a failed component may occur asynchronously with respect to execution of the program. In this study, an approach to dealing with ...
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ISBN:
(纸本)0818606908
One property that makes failures difficult to handle in programs is that the actions of a failed component may occur asynchronously with respect to execution of the program. In this study, an approach to dealing with this asynchrony is presented. It is based on treating a failure as an event in a concurrent system of processes, and then integrating failure handling mechanisms into distributed programming languages. The technique is illustrated by considering the class of failures suffered by fail-stop processors, and proposing extensions of the Synchronizing Resources (SR) distributed programming language to handle such failures. Two SR programs using these mechanisms are presented.
We describe a reliability algorithm being considered for DDM, a distributeddatabase system under development at Computer Corporation of America. The algorithm is designed to tolerate clean site failures in which site...
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ISBN:
(纸本)0897910974
We describe a reliability algorithm being considered for DDM, a distributeddatabase system under development at Computer Corporation of America. The algorithm is designed to tolerate clean site failures in which sites simply stop running. The algorithm allows the system to reconfigure itself to run correctly as sites fail and recover. The algorithm solves the subproblems of atomic commit and replicated data handling in an integrated manner.
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