10,892 research outputs found

    Towards Adaptable and Adaptive Policy-Free Middleware

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    We believe that to fully support adaptive distributed applications, middleware must itself be adaptable, adaptive and policy-free. In this paper we present a new language-independent adaptable and adaptive policy framework suitable for integration in a wide variety of middleware systems. This framework facilitates the construction of adaptive distributed applications. The framework addresses adaptability through its ability to represent a wide range of specific middleware policies. Adaptiveness is supported by a rich contextual model, through which an application programmer may control precisely how policies should be selected for any particular interaction with the middleware. A contextual pattern mechanism facilitates the succinct expression of both coarse- and fine-grain policy contexts. Policies may be specified and altered dynamically, and may themselves take account of dynamic conditions. The framework contains no hard-wired policies; instead, all policies can be configured.Comment: Submitted to Dependable and Adaptive Distributed Systems Track, ACM SAC 200

    Modeling Adaptive Middleware and Its Applications to Military Tactical Datalinks

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    Open systems solutions and techniques have become the de facto standard for achieving interoperability between disparate, large-scale, legacy software systems. A key technology among open systems solutions and techniques is middleware. Middleware, in general, is used to isolate applications from dependencies introduced by hardware, operating systems, and other low-level aspects of system architectures. While middleware approaches are or will be integrated into operational military systems, many open questions exist about the appropriate areas to applying middleware. Adaptive middleware is middleware that provides an application with a run-time adaptation strategy, based upon system-level interfaces and properties. Adaptive middleware is an example of an active applied research area. Adaptive middleware is being developed and applied to meet the ever-increasing challenges set forth by the next generation of mission-critical distributed real-time and embedded (DRE) systems. The driving force behind many next-generation DRE systems is the establishment of QoS requirements typically associated with workloads that vary dynamically. The Weapon System Open Architecture (WSOA), an adaptive middleware platform developed by Boeing, is modeled as a part of this research to determine the scalability of the architecture. The WSOA adaptive middleware was previously flight-tested with one tactical node, and the test results represent the performance baseline the architecture. The WSOA adaptive middleware is modeled with 1, 2, 4, 8 and 16 tactical nodes. The results of the modeling and simulation is that the WSOA adaptive middleware can achieve the performance baseline achieved during the original flight-test, in the cases of 1, 2, and 4 tactical nodes. In addition, the results of the modeling and simulation also demonstrate that the WSOA adaptive middleware cannot achiev

    VOLARE: Adaptive Web Service Discovery Middleware for Mobile Systems

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    With the recent advent and widespread use of smart mobile devices, the flexibility and versatility offered by Service Oriented Architecture's (SOA) makes it an ideal approach to use in the rapidly changing mobile environment. However, the mobile setting presents a set of new challenges that service discovery methods developed for nonmobile environments cannot address. The requirements a mobile client device will have from a Web service may change due to changes in the context or the resources of the client device. In a similar manner, a mobile device that acts as a Web service provider will have different capabilities depending on its status, which may also change dramatically during runtime. This paper introduces VOLARE, a middleware-based solution that will monitor the resources and context of the device, and adapt service requests accordingly. The same method will be used to adapt the Quality of Service (QoS) levels advertised by service providers, to realistically reflect each provider's capabilities at any given moment. This approach will allow for more resource-efficient and accurate service discovery in mobile systems and will enable more reliable provider functionality in mobile devices

    Ontology-based collaborative framework for disaster recovery scenarios

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    This paper aims at designing of adaptive framework for supporting collaborative work of different actors in public safety and disaster recovery missions. In such scenarios, firemen and robots interact to each other to reach a common goal; firemen team is equipped with smart devices and robots team is supplied with communication technologies, and should carry on specific tasks. Here, reliable connection is mandatory to ensure the interaction between actors. But wireless access network and communication resources are vulnerable in the event of a sudden unexpected change in the environment. Also, the continuous change in the mission requirements such as inclusion/exclusion of new actor, changing the actor's priority and the limitations of smart devices need to be monitored. To perform dynamically in such case, the presented framework is based on a generic multi-level modeling approach that ensures adaptation handled by semantic modeling. Automated self-configuration is driven by rule-based reconfiguration policies through ontology

    Context-aware adaptation in DySCAS

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    DySCAS is a dynamically self-configuring middleware for automotive control systems. The addition of autonomic, context-aware dynamic configuration to automotive control systems brings a potential for a wide range of benefits in terms of robustness, flexibility, upgrading etc. However, the automotive systems represent a particularly challenging domain for the deployment of autonomics concepts, having a combination of real-time performance constraints, severe resource limitations, safety-critical aspects and cost pressures. For these reasons current systems are statically configured. This paper describes the dynamic run-time configuration aspects of DySCAS and focuses on the extent to which context-aware adaptation has been achieved in DySCAS, and the ways in which the various design and implementation challenges are met

    The SATIN component system - a metamodel for engineering adaptable mobile systems

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    Mobile computing devices, such as personal digital assistants and mobile phones, are becoming increasingly popular, smaller, and more capable. We argue that mobile systems should be able to adapt to changing requirements and execution environments. Adaptation requires the ability-to reconfigure the deployed code base on a mobile device. Such reconfiguration is considerably simplified if mobile applications are component-oriented rather than monolithic blocks of code. We present the SATIN (system adaptation targeting integrated networks) component metamodel, a lightweight local component metamodel that offers the flexible use of logical mobility primitives to reconfigure the software system by dynamically transferring code. The metamodel is implemented in the SATIN middleware system, a component-based mobile computing middleware that uses the mobility primitives defined in the metamodel to reconfigure both itself and applications that it hosts. We demonstrate the suitability of SATIN in terms of lightweightedness, flexibility, and reusability for the creation of adaptable mobile systems by using it to implement, port, and evaluate a number of existing and new applications, including an active network platform developed for satellite communication at the European space agency. These applications exhibit different aspects of adaptation and demonstrate the flexibility of the approach and the advantages gaine
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