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.
This issue contains 11 selected conference papers. The topics covered include: fact-based analysis and design;translation of entity-relationship (ER) diagrams into relational structures;ER behavior modeling;ER algebra...
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This issue contains 11 selected conference papers. The topics covered include: fact-based analysis and design;translation of entity-relationship (ER) diagrams into relational structures;ER behavior modeling;ER algebra;computer-aided layout of ER diagrams;data administration support;dictionary systems.system development;a database-oriented tool generator;and reliability control for distributeddatabasesystems.
The authors propose two protocols for transaction processing in quasi-partitioned databases. The protocols are pessimistic in that they permit the execution of update transactions in exactly one partition. The first p...
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ISBN:
(纸本)0818608757
The authors propose two protocols for transaction processing in quasi-partitioned databases. The protocols are pessimistic in that they permit the execution of update transactions in exactly one partition. The first protocol is defined for a fully partition-replicated database in which every partition contains a copy of every data object. The second protocol is defined for a partially partition-replicated database in which some objects have no copies in some partitions. Both protocols improve their major performance measures linearly with the backup link speed but are not visibly affected by either duration of the partitioning or the database size. This is a desirable property, since the backup link speed is the only controllable parameter.
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.
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.
Highly reliable and effective failure detection and isolation (FDI) software is crucial in modern avionics systems.that tolerate hardware failures in real time. The FDI function is an excellent opportunity for applyin...
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ISBN:
(纸本)0818608757
Highly reliable and effective failure detection and isolation (FDI) software is crucial in modern avionics systems.that tolerate hardware failures in real time. The FDI function is an excellent opportunity for applying the principal of software design diversity to the fullest, i.e., algorithm diversity, in order to provide gains in functional performance as well as potentially enhancing the reliability of the software. The authors examine algorithm diversity applied to the redundancy management software for a hardware fault-tolerant sensor array. Results of an experiment are presented that show the performance gains that can be provided by utilizing the consensus of three diverse algorithms for sensor FDI.
software code reuse has long been touted as a reliable and efficient software development paradigm. Whilst this practice has numerous benefits, it is inherently susceptible to latent vulnerabilities. Source code which...
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ISBN:
(纸本)9780769542508
software code reuse has long been touted as a reliable and efficient software development paradigm. Whilst this practice has numerous benefits, it is inherently susceptible to latent vulnerabilities. Source code which is re-used without being patched for various reasons may result in vulnerable binaries, despite the vulnerabilities being made publicly known. To aggravate matters, crackers have access to information on these vulnerabilities as well. Defenders need to ensure all loopholes are patched, while attackers need just one such loophole. In this work, we define latent vulnerabilities, and study the prevalence of the problem. This provides us the motivation, and an insight into the future work to be done in solving the problem. Our results show that unpatched source files which are more than one year old are commonly used in the latest operating systems. In fact, several of these files are more than ten years old. We explore the premises of using symbols in identifying binaries and conclude that they are insufficient in solving the problem. Additionally, we discuss two possible approaches to solve the problem.
A recursive algorithm for computing a lower bound on the all-terminal reliability of an n-dimensional hypercube is presented. The recursive step decomposes an n-dimensional hypercube into lower dimension hypercubes th...
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A recursive algorithm for computing a lower bound on the all-terminal reliability of an n-dimensional hypercube is presented. The recursive step decomposes an n-dimensional hypercube into lower dimension hypercubes that are linked together. As an illustration of the effectiveness and power of this method, a lower bound is computed on the all-terminal reliability of the 16-dimensional hypercube (Connection Machine architecture) whose links number 219. The notation and assumptions are defined, and background information on bounding the reliability polynomial is provided. Methods for tightening these bounds for the analysis of the hypercube architecture are discussed.
The following topics are dealt with: distributed operating systems.local area networks;network fault tolerance;hypercubes;distributeddatabases;real-time systems.replicated programs;computer architectures;and voting. ...
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The following topics are dealt with: distributed operating systems.local area networks;network fault tolerance;hypercubes;distributeddatabases;real-time systems.replicated programs;computer architectures;and voting. Abstracts of individual papers can be found under the relevant classification codes in this or other issues.
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