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The use of gateway proxies is one important approach to facilitating adaptation across wireless and mobile environments. Importantly, augmented service entities deployed within the gateway proxy residing on the wired network can be composed and deployed to shield mobile clients from the effects of poor network characteristics. The usual approach to the static composition of service entities on the gateway proxy is to have these service entities interact with each other by explicitly invoking procedures on the named interface, but such a tight coupling of interfaces inhibits the flexible composition and adaptation of the service entities to the dynamic operating characteristics of wireless networks. In this paper, we present a Mobile gateway for the Active deployment of Transport Entities or, for short, MobiGATE (pronounced Mobi-Gate). MobiGATE is a mobile middleware framework that supports the robust and flexible composition of transport entities, known as streamlets. The flow of data traffic is subjected to processing by a chain of streamlets. Each streamlet encapsulates a service entity that adapts the flow of traffic across the wireless network. To facilitate the dynamic reconfiguration of the streamlets, we advocate applying the concept of coordination as the unifying approach to composing these transport service entities. Importantly, MobiGATE delineates a clear separation of interdependent parts from the service-specific computational codes of those service entities. It does this by using a separate coordination language, called MobiGATE Coordination Language (MCL), to describe the coordination among streamlet service entities. The complete design, implementation, and evaluation of the MobiGATE system are presented in this paper. Initial experimental results validate the flexibility of the coordination approach in promoting separation-of-concern in the reconfiguration of services, while achieving low computation and delay overheads. [ABSTRACT FROM AUTHOR]

The port-based object is a new software abstraction for designing and implementing dynamically reconfigurable real-time software. It forms the basis of a programming model that uses domain-specific elemental units to provide specific, yet flexible, guidelines to control engineers for creating and integrating software components. We use a port-based object abstraction, based on combining the notion of an object with the port-automaton algebraic model of concurrent processes. It is supported by an implementation using domain-specific communication mechanisms and templates that have been incorporated into the Chimera Real-Time Operating System and applied to several robotic applications. This paper describes the port-based object abstraction, provides a detailed analysis of communication and synchronization based on distributed shared memory, and describes a programming paradigm based on a framework process and code templates for quickly implementing applications. [ABSTRACT FROM AUTHOR]

I/O abstraction is offered as a new high-level approach to interprocess communication. Functional components of a distributed system are written as encapsulated modules that act upon local data structures, some of which may be published for external use. Relationships among modules are specified by logical connections among their published data structures. Whenever a module updates published data, I/O takes place implicitly according to the configuration of logical connections. The Programmers' Playground, a software library and run- time system supporting I/O abstraction, is described. Design goals include the separation of communication from computation, dynamic reconfiguration of the communication structure, and the uniform treatment of discrete and continuous data types. Support for end-user configuration of distributed multimedia applications is the motivation for the work. [ABSTRACT FROM AUTHOR]

A major challenge of dynamic reconfiguration is Quality of Service (QoS) assurance, which is meant to reduce application disruption to the minimum for the system's transformation. However, this problem has not been well studied. This paper investigates the problem for component-based software systems from three points of view. First, the whole spectrum of QoS characteristics is defined. Second, the logical and physical requirements for QoS characteristics are analyzed and solutions to achieve them are proposed. Third, prior work is classified by QoS characteristics and then realized by abstract reconfiguration strategies. On this basis, quantitative evaluation of the QoS assurance abilities of existing work and our own approach is conducted through three steps. First, a proof-of-concept prototype called the reconfigurable component model is implemented to support the representation and testing of the reconfiguration strategies. Second, a reconfiguration benchmark is proposed to expose the whole spectrum of QoS problems. Third, each reconfiguration strategy is tested against the benchmark and the testing results are evaluated. The most important conclusion from our investigation is that the classified QoS characteristics can be fully achieved under some acceptable constraints. [ABSTRACT FROM PUBLISHER]