Session-Based Role Programming for the Design of Advanced Telephony Applications

International audienceStimulated by new protocols like SIP, telephony applications are rapidly evolving to o er and combine a variety of communications forms including presence status, instant messaging and videoconferencing. This situation changes and complicates significantly the programming of telephony applications that consist now of distributed entities involved into multiple heterogeneous, stateful and long-running interactions. This paper proposes an approach to support the development of SIP-based telephony applications based on general programming language. Our approach combines the concepts of Actor, Session and Role. Role is the part an actor takes in a session and we consider a session as a collaboration between roles. By using these concepts, we are able to break the complexity of SIP entities programming and provide flexibility for defi ning new ones. Our approach is implemented as a coding framework above JAIN-SIP

Assessing composition in modeling approaches

Modeling approaches are based on various paradigms, e.g., aspect-oriented, feature-oriented, object-oriented, and logic-based. Modeling approaches may cover requirements models to low-level design models, are developed for various purposes, use various means of composition, and thus are difficult to compare. However, such comparisons are critical to help practitioners know under which conditions approaches are most applicable, and how they might be successfully generalized and combined to achieve end-to-end methods. This paper reports on work done at the 2nd International Comparing Modeling Approaches (CMA) workshop towards the goal of identifying potential comprehensive modeling methodologies with a particular emphasis on composition: (i) an improved set of comparison criteria; (ii) 19 assessments of modeling approaches based on the comparison criteria and a common, focused case study

Utilizing Connectivity Maps to Accelerate V2I Communication in Cellular Network Dead Spots

On many roads in rural and mountainous areas, the cellular network connectivity is intermittent and dead spots, i.e., zones without any coverage, are frequent. In previous work, we developed a data dissemination protocol to accelerate the transmission of messages in dead spots. It combines the cellular network with short-living ad-hoc networks between vehicles. A car in a dead spot can forward messages directed towards the environment, to the peer in its ad-hoc network that will leave the dead spot first, effectively reducing the delay. An issue, however, is to reliably identify the peer that is most likely the first one regaining cellular network coverage. This problem can be solved if the borders of the dead spot, the vehicles are in, are previously known. For that, we use a novel technology named dead spot prediction. Here, vehicles conduct local connectivity measurements that are aggregated to so-called connectivity maps describing the locations of dead spots on a road system. In this article, we introduce the combination of the data dissemination protocol with dead spot prediction. Particularly, our protocol is amended such that connectivity maps are considered when deciding which vehicle leaves a dead spot first. Since currently only few publicly available works about dead spot prediction exist, we further created a prototype of such a predictor ourselves that will be discussed as well

Towards Dynamic Composition of Hybrid Communication Services

Due to the deregulation of the telecom network and the Internet, users will have access to an increasing number of heterogeneous communication services and will need to adapt their services or learn new services in order to interact with other users and systems. We propose a dynamic composition method that ena- bles services to be constructed dynamically or "on-the-fly" from existing functional elements (service roles). Roles and actors that play roles are key concepts in our approach. A service role is defined as the part an object takes in a service. Service execution requires that roles are assigned to actors in a coordinated way. Our approach enables the systematic and structured specification of services, and provides mechanisms for service composition and an execution environment