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Software, IEE Proceedings -

Issue 5 • Date Oct 1998

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Displaying Results 1 - 8 of 8
  • On the role of software architectures in runtime system reconfiguration

    Page(s): 137 - 145
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1048 KB)  

    Society's increasing dependence on software-intensive systems is driving the need for dependable, robust, continuously available systems. Runtime system reconfiguration is one aspect of achieving continuous availability. We present an architecture-based approach to runtime software reconfiguration, highlighting the beneficial role of architectural styles and software connectors in facilitating runtime change. We conclude by describing the implementation of our tool suite, called ArchStudio, that supports runtime reconfiguration using our architecture-based approach View full abstract»

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  • Managing inconsistency in reconfigurable systems

    Page(s): 172 - 179
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (904 KB)  

    This paper discusses an approach to managing inconsistencies in real-time control applications that are the result of dynamic reconfiguration. In particular, systems based on Simplex are examined: a fault tolerant technology that supports dependable upgrade of systems. Simplex-based systems tolerate residual errors in upgraded components and can be upgraded incrementally and while the system is in operation. Runtime reconfiguration is a key mechanism for Simplex. Reconfiguration of components due to an encountered error may result in inconsistent configurations. The paper focuses on design time analysis to determine inconsistencies in configurations and identify reconfiguration paths to recover to consistent configurations. Runtime support uses the analysis results to recover from inconsistent configurations. Identification of inconsistent configurations is improved through modelling of application semantics in the control domain and utilising them in the analysis View full abstract»

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  • Configuration management for highly customisable software

    Page(s): 180 - 188
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1192 KB)  

    Customisable operating systems, database systems, and communication subsystems have demonstrated many advantages of customisation, including considerable performance improvements. One common approach for constructing customisable software is to implement it as a collection of modules that can be configured in different combinations to provide customised variants of the software. Typically, ad hoc methods are used to determine which modules may be combined. Such methods require intimate knowledge of the modules and their interactions or the configuration will not behave as expected. In this paper, we present a methodology that simplifies the difficult task of constructing correct custom variants of highly customisable software. The methodology is based on identifying relations between software modules that dictate which combinations are correct. We also introduce a configuration support tool that, based on these relations, allows only correct configurations to be created View full abstract»

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  • Towards a chemical model for software architecture reconfiguration

    Page(s): 130 - 136
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (804 KB)  

    The chemical abstract machine is a general-purpose, simple, and intuitive programming model. Among other domains, it has been used for the specification and analysis of the computational behaviour of software architectures. In this paper we explore the ability of the formalism to express the dynamics of the architecture itself and to unify approaches to reconfiguration within framework View full abstract»

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  • Architectural support for dynamic reconfiguration of distributed workflow applications

    Page(s): 155 - 162
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    In a distributed environment, it is inevitable that long running applications require support for dynamic reconfiguration because, for example, machines may fail, services may be moved or withdrawn and user requirements may change. In such an environment it is essential that the structure of running applications can be modified to reflect such changes. A complication is that such long running applications are frequently composed out of existing applications. The resulting application can be very complex in structure, containing many temporal dependencies between constituent applications. This paper describes an approach that supports the dynamic reconfiguration of a class of large-scale distributed applications that represent business processes (commonly referred to as workflows). An application composition and execution environment has been designed and implemented as a transactional workflow system that enables sets of inter-related tasks (applications) to be carried out and supervised in a dependable manner. A task model that is expressive enough to represent temporal dependencies between constituent tasks has been developed. The workflow system maintains this structure and makes it available through transactional operations for performing changes to it. Use of transactions ensures that changes can be carried out atomically with respect to running applications. The workflow system is general purpose and open: it has been designed and implemented as a set of CORBA services to run on top of a given ORB View full abstract»

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  • Software architecture for adaptive distributed multimedia systems

    Page(s): 163 - 171
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    To support multimedia applications in mobile environments, it will be necessary for applications to be aware of the underlying network conditions and also to be able to adapt their behaviour and that of the underlying platform. This paper focuses on the role of middleware in supporting such adaptation. In particular, it investigates the role of open implementation and reflection in the design of middleware platforms such as CORBA. The paper initially extends CORBA with the concept of explicit binding, where path of communication between objects is represented as first class objects. We then introduce the concept of open bindings which support inspection and adaptation of the path of communications. An implementation of open bindings for adaptive continuous-media interaction is described using the example of adaptive video-on-demand for mobile environments View full abstract»

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  • Analysing dynamic change in distributed software architectures

    Page(s): 146 - 154
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1108 KB)  

    The software architecture of a system is the overall structure of the system in terms of its constituent components and their interconnections. Dynamic changes to the instantiated system architecture (to the components and/or interconnections) may take place while it is running. In order that these changes do not violate the integrity of the system, we adopt a general model of dynamic configuration which only permits change to occur when the affected portions of the system are quiescent. This paper investigates the feasibility of performing behaviour analysis on systems which conform to the change model. The analysis approach associates behavioural specifications with the components of a software architecture and analyses the behaviour of systems composed from these components. The changes that can occur are modelled as constraints on the architecture, thereby permitting incremental and even concurrent changes. Analysis is used to check that the architecture satisfies the properties required of it: before, during and after the changes. The paper uses an example to illustrate the approach View full abstract»

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