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Shesh N. Rai - One of the best experts on this subject based on the ideXlab platform.

  • The optimal Class size for object-oriented software
    IEEE Transactions on Software Engineering, 2002
    Co-Authors: K. El Emam, S. Benlarbi, N. Goel, Walcélio L. Melo, Hakim Lounis, Shesh N. Rai
    Abstract:

    A growing body of literature suggests that there is an optimal size for software Components. This means that Components that are too small or too big will have a higher defect content (i.e., there is a U-shaped curve relating defect content to size). The U-shaped curve has become known as the "Goldilocks Conjecture." Recently, a cognitive theory has been proposed to explain this phenomenon and it has been expanded to characterize object-oriented software. This conjecture has wide implications for software engineering practice. It suggests 1) that designers should deliberately strive to design Classes that are of the optimal size, 2) that program decomposition is harmful, and 3) that there exists a maximum (threshold) Class size that should not be exceeded to ensure fewer faults in the software. The purpose of the current paper is to evaluate this conjecture for object-oriented systems. We first demonstrate that the claims of an optimal Component/Class size (1) above) and of smaller Components/Classes having a greater defect content (2) above) are due to a mathematical artifact in the analyses performed previously. We then empirically test the threshold effect claims of this conjecture (3) above). To our knowledge, the empirical test of size threshold effects for object-oriented systems has not been performed thus far. We performed an initial study with an industrial C++ system and repeated it twice on another C++ system and on a commercial Java application. Our results provide unambiguous evidence that there is no threshold effect of Class size. We obtained the same result for three systems using four different size measures. These findings suggest that there is a simple continuous relationship between Class size and faults, and that, optimal Class size, smaller Classes are better and threshold effects conjectures have no sound theoretical nor empirical basis.

  • The Optimal Class Size for Object-Oriented Software : A Replicated Study
    2000
    Co-Authors: Khaled El-emam, S. Benlarbi, N. Goel, Walcélio L. Melo, Hakim Lounis, Khaled El Emam, Shesh N. Rai
    Abstract:

    A growing body of literature suggests that there is an optimal size for software Components. This means that Components that are too small or too big will have a higher defect content (i.e., there is a U-shaped curve relating defect content to size). The U-shaped curve has become known as the “Goldilocks Conjecture”. Recently, a cognitive theory has been proposed to explain this phenomenon, and it has been expanded to characterize object-oriented software. This conjecture has wide implications for software engineering practice. It suggests (1) that designers should deliberately strive to design Classes that are of the optimal size, (2) that program decomposition is harmful, and (3) that there exists a maximum (threshold) Class size that should not be exceeded to ensure fewer faults in the software. The purpose of the current paper is to evaluate this conjecture for object-oriented systems. We first demonstrate that the claims of an optimal Component/Class size (1 above) and of smaller Components/Classes having a greater defect content (2 above) are due to a mathematical artifact in the analyses performed previously. We then empirically test the threshold effect claims of this conjecture (3 above). To our knowledge, the empirical test of size threshold effects for object-oriented systems has not been performed thus far. We perform an initial study with an industrial C++ system, and replicated it twice on another C++ system and on a commercial Java application. Our results provide unambiguous evidence that there is no threshold effect of Class size. We obtained the same result for three systems using 4 different size measures. These findings suggest that there is a simple continuous relationship between Class size and faults, and that optimal Class size, smaller Classes are better, and threshold effects conjectures have no sound theoretical nor empirical basis.

James W Ragucci - One of the best experts on this subject based on the ideXlab platform.

  • don t be a phish steps in user education
    Technical Symposium on Computer Science Education, 2006
    Co-Authors: Stefan A Robila, James W Ragucci
    Abstract:

    Phishing, e-mails sent out by hackers to lure unsuspecting victims into giving up confidential information, has been the cause of countless security breaches and has experienced in the last year an increase in frequency and diversity. While regular phishing attacks are easily thwarted, designing the attack to include user context information could potentially increase the user's vulnerability. To prevent this, phishing education needs to be considered. In this paper we provide an overview of phishing education, focusing on context aware attacks and introduce a new strategy for educating users by combining phishing IQ tests and Class discussions. The technique encompasses displaying both legitimate and fraudulent e-mails to users and having them identify the phishing attempts from the authentic e-mails. Proper implementation of this system helps teach users what to look for in e-mails, and how to protect their confidential information from being caught in the nets of phishers. The strategy was applied in Introduction to Computing courses as part of the computer security Component. Class assessment indicates an increased level of awareness and better recognition of attacks.

Marianne Huchard - One of the best experts on this subject based on the ideXlab platform.

  • Foundations of a Simple and Unified Component-Oriented Language
    Computer Languages Systems and Structures, 2008
    Co-Authors: Luc Fabresse, Christophe Dony, Marianne Huchard
    Abstract:

    Component-oriented programming is actually a key research track in software engineering. A variety of Component-oriented languages have been proposed with new or adapted abstractions and mechanisms to support this new paradigm. However, the proposed features vary quite widely from one proposal to another. There is a need for a closer analysis and synthesis of these features to really discover the new possibilities of Component-oriented programming. In this article we present Scl, our proposition of simple language dedicated to Component-oriented programming. Through the presentation of Scl, we discuss and compare the main features of Component-oriented languages such as Component Class, Component, interface, port, service or connector. But, these features are not enough to build a Component-oriented language. Indeed, unanticipated connection of independently developed Components is one of the key issues of Component-oriented programming. Most approaches use language primitives or connectors and shared interfaces to connect Components. But shared interfaces are in contradiction with the philosophy of independently developed Components. The approach of Scl is to provide a uniform Component connection mechanism based on special Components called connectors. Scl also integrates Component properties which enable connections based on Component state changes with no requirements of specific code in Components.

  • SCL: a Simple, Uniform and Operational Language for Component-Oriented Programming in Smalltalk
    2007
    Co-Authors: Luc Fabresse, Christophe Dony, Marianne Huchard
    Abstract:

    Unanticipated connection of independently developed Components is one of the key issues in Component-oriented programming. While a variety of Component-oriented languages have been proposed, none of them has achieved a breakthrough yet. In this paper, we present Scl a simple language dedicated to Component-oriented programming. Scl integrates well-known features such as Component Class, Component, interface, port or service. All these well-known features are presented, discussed and compared to existing approaches because they vary quite widely from one language to another. But, these features are not enough to build a Component language. Indeed, most approaches use language primitives and shared interfaces to connect Components. But shared interfaces are in contradiction with the philosophy of independently developed Components. To this issue, Scl provides new features such as a uniform Component composition model based on connectors. Connectors represent interactions between independently developed Components. Scl also integrates Component properties which enable connections based on Component state changes with no requirements of specific code in Components.

Dijkhuizen L. - One of the best experts on this subject based on the ideXlab platform.

  • Molecular and functional characterization of kshA and kshB, encoding two Components of 3-ketosteroid 9 alpha-hydroxylase, a Class IA monooxygenase, in Rhodococcus erythropolis strain SQ1
    2002
    Co-Authors: Van Der Geize R, Gi Hessels, Van Gerwen R, Van Der Meijden R, Dijkhuizen L.
    Abstract:

    9alpha-Hydroxylation of 4-androstene-3,17-dione (AD) and 1,4-androstadiene-3,17-dione (ADD) is catalysed by 3-ketosteroid 9alpha-hydroxylase (KSH), a key enzyme in microbial steroid catabolism. Very limited knowledge is presently available on the KSH enzyme. Here, we report for the first time the identification and molecular characterization of genes encoding KSH activity. The kshA and kshB genes, encoding KSH in Rhodococcus erythropolis strain SQ1, were cloned by functional complementation of mutant strains blocked in AD(D) 9alpha-hydroxylation. Analysis of the deduced amino acid sequences of kshA and kshB showed that they contain domains typically conserved in Class IA terminal oxygenases and Class IA oxygenase reductases respectively. By definition, Class IA oxygenases are made up of two Components, thus Classifying the KSH enzyme system in R. erythropolis strain SQ1 as a two-Component Class IA monooxygenase composed of KshA and KshB. Unmarked in frame gene deletion mutants of parent strain R. erythropolis SQ1, designated strains RG2 (kshA mutant) and RG4 (kshB mutant), were unable to grow on steroid substrates AD(D), whereas growth on 9alpha-hydroxy-4-androstene-3,17-dione (9OHAD) was not affected. Incubation of these mutant strains with AD resulted in the accumulation of ADD (30-50% conversion), confirming the involvement of KshA and KshB in AD(D) 9alpha-hydroxylation. Strain RG4 was also impaired in sterol degradation, suggesting a dual role for KshB in both sterol and steroid degradation

  • Molecular and functional characterization of kshA and kshB, encoding two Components of 3-ketosteroid 9α-hydroxylase, a Class IA monooxygenase, in Rhodococcus erythropolis strain SQ1
    2002
    Co-Authors: Geize R. Van Der, Hessels G.i., Gerwen R. Van, Meijden P. Van Der, Dijkhuizen L.
    Abstract:

    9α-Hydroxylation of 4-androstene-3,17-dione (AD) and 1,4-androstadiene-3,17-dione (ADD) is catalysed by 3-ketosteroid 9α-hydroxylase (KSH), a key enzyme in microbial steroid catabolism. Very limited knowledge is presently available on the KSH enzyme. Here, we report for the first time the identification and molecular characterization of genes encoding KSH activity. The kshA and kshB genes, encoding KSH in Rhodococcus erythropolis strain SQ1, were cloned by functional complementation of mutant strains blocked in AD(D) 9α-hydroxylation. Analysis of the deduced amino acid sequences of kshA and kshB showed that they contain domains typically conserved in Class IA terminal oxygenases and Class IA oxygenase reductases respectively. By definition, Class IA oxygenases are made up of two Components, thus Classifying the KSH enzyme system in R. erythropolis strain SQ1 as a two-Component Class IA monooxygenase composed of KshA and KshB. Unmarked in frame gene deletion mutants of parent strain R. erythropolis SQ1, designated strains RG2 (kshA mutant) and RG4 (kshB mutant), were unable to grow on steroid substrates AD(D), whereas growth on 9α-hydroxy-4-androstene-3,17-dione (9OHAD) was not affected. Incubation of these mutant strains with AD resulted in the accumulation of ADD (30–50% conversion), confirming the involvement of KshA and KshB in AD(D) 9α-hydroxylation. Strain RG4 was also impaired in sterol degradation, suggesting a dual role for KshB in both sterol and steroid degradation.

Peng Zhi - One of the best experts on this subject based on the ideXlab platform.

  • Realization of Workflow Views Based on Object Deputy Model
    Chinese Journal of Computers, 2005
    Co-Authors: Peng Zhi
    Abstract:

    Workflow views adapted from the concept of views in databases are mainly used to support workflow inter operability and flexibility under Web service environment in order to meet the needs of different applications. However, there are not any proper mechanisms for realization of workflow views. This paper discusses how to realize workflow views based on object deputy model. The formal definitions of the deputy Class and the deputy algebra for workflow Classes are given. According to the process meta model of XPDL, we can derive deputy Classes from each kind of workflow Component Class so that flexible workflow views can be realized.