Apostolos V. Zarras

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Providing software qualities such as availability, adaptability and maintenability to long-running distributed applications, forms a major challenge for the configuration management of a software system. Modifications of system’s structure are expected to happen on-the-fly, to cause minimum execution disruption, and to be effected in a way that preserves a(More)
In this paper we present CoWSAMI, a middleware infrastructure that enables context awareness in open ambient intelligence environments, consisting of mobile users and context sources that become dynamically available as the users move from one location to another. A central requirement in such dynamic scenarios is to be able to integrate new context sources(More)
Service-oriented computing is now acknowledged as a central paradigm for Internet computing, supported by tremendous research and technology development over the last 10 years. However, the evolution of the Internet, and in particular, the latest Future Internet vision, challenges the paradigm. Indeed, service-oriented computing has to face the ultra large(More)
Future middleware platforms will need to be more configurable in order to meet the demands of a wide variety of application domains. Furthermore, we believe that such platforms will also need to be reconfigurable, for example to enable systems to adapt to changes in the underlying systems infrastructure. A number of technologies are emerging to support this(More)
Software cohesion concerns the degree to which the elements of a module belong together. Cohesive software is easier to understand, test and maintain. In the context of service-oriented development, cohesion refers to the degree to which the operations of a service interface belong together. In the state of the art, software cohesion is improved based on(More)
This paper focuses on the development of a principled methodology for the dependability analysis of composite Web services. The first step of the methodology involves a UML representation for the architecture specification of composite Web services. The proposed representation is built upon BPEL and introduces necessary extensions to support the second step(More)
The problem we deal with in this paper is the dynamic substitution of stateful services that become unavailable during the execution of service orchestrations. Previous research efforts focusing on the reconfiguration of conventional distributed systems enable the substitution of system entities with other prefabricated passive entities that serve as a(More)
This chapter establishes a common base for discussing reconfigurability in distributed software systems in general and in pervasive systems in particular, by introducing a generic reconfiguration cycle. Following this cycle, we discuss in detail three former efforts on reconfigurable pervasive systems, and draw conclusions about the capacity of existing(More)