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Software, IEE Proceedings -

Issue 3 • Date June 2001

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Displaying Results 1 - 5 of 5
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  • Formal support for dynamic QoS management in the development of open component-based distributed systems

    Page(s): 89 - 97
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1280 KB)  

    An aspect-oriented specification technique that supports the specification of component-based distributed systems is presented. Importantly, this technique also supports the synthesis of quality-of-service (QoS) management components from particular aspects of the specification. It is described how, by using a tool to support the aspect-oriented environment, one can first specify and verify QoS management subsystems and then synthesise components that can be placed into a running system. The focus is on dynamic QoS management functions, particularly monitoring and adaptation. The approach is illustrated by giving a simple example of the dynamic QoS management of an audio stream View full abstract»

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  • Connectors for bridging mismatches between the components of a software engineering environment

    Page(s): 104 - 111
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1044 KB)  

    Software engineering environments (SEEs) are complex systems, for which configurability is an important requirement. Constructing SEEs out of existing tools is evidently desirable. During such a composition, mismatches between the data models of different tools will arise. The brute-force technique of hacking data translators into the implementation of individual tools has severe drawbacks regarding the modularity, maintainability and extensibility of the composed system. This paper proposes a novel technique for designing SEEs that uses explicit language constructs for bridging the mismatches in the data models, called dynamic view connectors. It shows how the separation of tool functionality from the concerns of bridging data-model mismatches improves the configurability and maintainability of an existing SEE View full abstract»

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  • What accuracy statistics really measure [software estimation]

    Page(s): 81 - 85
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (660 KB)  

    Provides the software estimation research community with a better understanding of the meaning of, and relationship between, two statistics that are often used to assess the accuracy of predictive models: the mean magnitude relative error (MMRE) and the number of predictions within 25% of the actual, pred(25). It is demonstrated that MMRE and pred(25) are, respectively, measures of the spread and the kurtosis of the variable z, where z=estimate/actual. Thus, z is considered to be a measure of accuracy, and statistics such as MMRE and pred(25) to be measures of properties of the distribution of z. It is suggested that measures of the central location and skewness of z, as well as measures of spread and kurtosis, are necessary. Furthermore, since the distribution of z is non-normal, non-parametric measures of these properties may be needed. For this reason, box-plots of z are useful alternatives to simple summary metrics. It is also noted that the simple residuals are better behaved than the z variable, and could also be used as the basis for comparing prediction systems View full abstract»

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  • Component-based software engineering for distributed embedded real-time systems

    Page(s): 99 - 103
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    The aim of component-based software engineering is to create applications from reusable, exchangeable and connectable components. However, current component models lack support for important concepts of distributed embedded real-time systems, such as execution time and resource usage. These non-functional properties of a component are as important as its functionality. In addition, the non-functional properties are influenced by the platform on which the component is executed. A component model is proposed that separates the component's functionality from the platform-specific issues of concurrency, synchronisation and distribution. A technique that describes the behaviour of a component in a path-based notation similar to use case maps (UCMs) is presented. A method for deducing from these descriptions the behaviour of an application that consists of connected components is also shown. The paths also contain information on real-time requirements of the application. The authors also show how to adapt the components to an execution platform and how to create real-time applications with predictable properties from these components View full abstract»

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