To ensure high reliability and storage efficiency, erasure codes are preferred in storage systems. With the prevalent of distributed storage systems such as clouds storage, how to design a scalable and efficient erasu...
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ISBN:
(纸本)9781479932153
To ensure high reliability and storage efficiency, erasure codes are preferred in storage systems. With the prevalent of distributed storage systems such as clouds storage, how to design a scalable and efficient erasure-resilient code is challenging. We propose a scalable binary linear code to keep up with data growth which has the following properties. Given the group size k and the code block length n, the proposed code corrects any two bit erasures among the n bits. The redundancy overhead of the code is 2/(k + 2), and each data bit affects exactly 2 parity bits. As results of these properties, if a data bit is changed or added, only two parity bits need to be updated;and the recovery of an erasured bit requires accessing at most k other bits and the recovery of two erasured bits requires at most 2k other bits. We give the construction algorithm by the order expansion of regular graphs;moreover, we optimize the failure resilience during the construction procedure. Compared with existing codes, our proposed code has notable benefits in storage scalability, redundancy overhead and I/O bandwidth. The deployment of the proposed code in distributed storage systems can be simple and practical.
Offshore software development outsourcing is a contractual business of high quality software production at offshore destination(s) with significant cost-saving. The objective of this research paper is to identify chal...
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ISBN:
(纸本)9780889869226
Offshore software development outsourcing is a contractual business of high quality software production at offshore destination(s) with significant cost-saving. The objective of this research paper is to identify challenges in offshore software development outsourcing. We have performed questionnaire surveys with 53 experts from a total of 20 different countries. We asked the participants to rank each challenge on a five-point scale to determine the perceived importance of each challenge. Our survey included challenges identified in the previous findings of our systematic literature review. Our study reveals both 'lack of technical capability' and 'poor quality of service and system/process' as the critical challenges in offshore software development outsourcing. Our results also indicate that 'hidden costs', 'communication gap', 'poor infrastructure' and 'lack of control over project' are critical in the opinions of different groups of practitioners.
Some users may misbehave under the cover of anonymity by, e.g., defacing webpages on Wikipedia or posting vulgar comments on YouTube. To prevent such abuse, a few anonymous credential schemes have been proposed that r...
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Affecting multiple parts in software systems, security requirements often tangle with functional requirements. In order to separate crosscutting concerns and increase modularity, we propose to represent security requi...
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Affecting multiple parts in software systems, security requirements often tangle with functional requirements. In order to separate crosscutting concerns and increase modularity, we propose to represent security requirements as aspects that can be woven into functional requirements. Using problem frames to model the functional requirements, weaving is achieved by composing the modules representing security aspects with the requirement models. Moreover, we provide guidance on how such security aspects are structured to implement a particular access control solution. As a result, such security aspects become reusable solution patterns to refine the structure of security-related problem.
With the ability to leak confidential information in a secret manner, covert channels pose a significant threat to the confidentiality of a system. Due to this threat, the identification of covert channel existence has be...
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With the ability to leak confidential information in a secret manner, covert channels pose a significant threat to the confidentiality of a system. Due to this threat, the identification of covert channel existence has become an important part of the evaluation of secure systems. In this paper, we present a state-of-the-art survey discussing the conditions for covert channel existence found in the literature and we point to their inadequacy. We also examine how conditions for covert channel existence are handled by information theory. We propose a set of necessary and verifiable conditions for covert channel existence in systems of communicating agents. We aim to provide an improved understanding of covert channel communication and to build a foundation for developing effective and efficient mechanisms for mitigating covert channels in systems of communicating agents at the early stages of software development
With the development of information technology and social progress, human demand for information has become increasingly diverse, wherever and whenever people want to be able to easily, quickly and flexibly via voice,...
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With the development of information technology and social progress, human demand for information has become increasingly diverse, wherever and whenever people want to be able to easily, quickly and flexibly via voice, data, images and video and other means to communicate. Visual information to the people direct and vivid image, image / video transmission also been widespread attention. Although the third generation mobile communication systems and the emergence and rapid development of IP networks, making video communications is becoming the main business of the wireless communications, however, the actual wireless and IP channel will lead to error generation, such as: wireless channel multi- fading channels generated error and blocking IP packet loss and so on. Due to channel bandwidth limitations, the video communication compression coding of data is often beyond the data, and compress data after the error is very sensitive to error conditions caused a serious decline in image quality.
Aspect-orientation is a paradigm for managing the separation of crosscutting concerns and decomposing a system using more than one criterion. This paper proposes an aspect-oriented approach at the feature-modeling lev...
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Aspect-orientation is a paradigm for managing the separation of crosscutting concerns and decomposing a system using more than one criterion. This paper proposes an aspect-oriented approach at the feature-modeling level to better handle crosscutting concerns in the modeling of product families of ambient *** on the specification language of PFA (Product Family Algebra), we present a language AO-PFA (Aspect-Oriented Product Family Algebra) that extends the aspect-oriented paradigm to feature modeling. The language provides full facilities for articulating aspects, advice, and pointcuts in feature modeling. We illustrate the scope and flexibility of the proposed language through the discussion of several feature-modeling situations.
A program family might degenerate due to unplanned changes in its implementation, thus hindering the maintenance of family members. This degeneration is often induced by feature code that is changed individually in ea...
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