Abstract
Various programming languages allow the construction of structure-shy programs. Such programs are defined generically for many different datatypes and only specify specific behavior for a few relevant subtypes. Typical examples are XML query languages that allow selection of subdocuments without exhaustively specifying intermediate element tags. Other examples are languages and libraries for polytypic or strategic functional programming and for adaptive object-oriented programming. In this paper, we present an algebraic approach to transformation of declarative structure-shy programs, in particular for strategic functions and XML queries. We formulate a rich set of algebraic laws, not just for transformation of structure-shy programs, but also for their conversion into structure-sensitive programs and vice versa. We show how subsets of these laws can be used to construct effective rewrite systems for specialization, generalization, and optimization of structure-shy programs. We present a type-safe encoding of these rewrite systems in Haskell which itself uses strategic functional programming techniques. We discuss the application of these rewrite systems for XPath query optimization and for query migration in the context of schema evolution.

Abstract
The transmission of multimedia content between mobile devices is increasingly an area of exploration. The evolution of mobile devices and networks that support them, provide potential to create more sophisticated and innovating services. The fact that the Android platform does not provide the SIP protocol in its architecture, is a limiting factor for the development of new streaming applications. Throughout this paper the Android platform is presented, and more specifically the streaming protocols supported by the current streaming Media Framework. Based on the current Android Media Framework, this paper presents a possible architecture for the integration of the SIP protocol. The integration of this architecture is to surpass the limitations of the current Android platform and promote an improved performance in the current SIP applications, which is reflected in a lower power consumption of the device. © 2011 IEEE.

Abstract
Synchronous coordination systems allow the exchange of data by logically indivisible actions involving all coordinated entities. This paper introduces behavioural automata, a logically synchronous coordination model based on the Reo coordination language, which focuses on relevant aspects for the concurrent evolution of these systems. We show how our automata model encodes the Reo and Linda coordination models and how it introduces an explicit predicate that captures the concurrent evolution, distinguishing local from global actions, and lifting the need of most synchronous models to involve all entities at each coordination step, paving the way to more scalable implementations. © J. Proença, D. Clarke, E. de Vink & F. Arbab.

Abstract
Coordination in Reo emerges from the composition of the behavioural constraints of primitives, such as channels, in a component connector. Understanding and implementing Reo, however, has been challenging due to the interaction of the channel metaphor, which is an inherently local notion, and the non-local nature of the constraints imposed by composition. In this paper, the channel metaphor takes a back seat. We focus on the behavioural constraints imposed by the composition of primitives and phrase the semantics of Reo as a constraint satisfaction problem. Not only does this provide a clear description of the behaviour of Reo connectors in terms of synchronisation and data flow constraints, it also paves the way for new implementation techniques based on constraint satisfaction. We also demonstrate that this approach is more efficient than the existing techniques based on connector colouring.

Abstract
The HATS project aims at developing a model-centric methodology for the design, implementation and verification of highly configurable systems, such as software product lines, centred around the Abstract Behavioural Specification (ABS) modelling Language. This article describes the variability modelling features of the ABS Modelling framework. It consists of four languages, namely, µTVL for describing feature models at a high level of abstraction, the Delta Modelling Language DML for describing variability of the 'code' base in terms of delta modules, the Product Line Configuration Language CL for linking feature models and delta modules together and the Product Selection Language PSL for describing a specific product to extract from a product line. Both formal semantics and examples of each language are presented. © 2011 Springer-Verlag Berlin Heidelberg.

Abstract
Formal modelling and verification are critical for managing the inherent complexity of systems with a high degree of variability, such as those designed following the software product line (SPL) paradigm. SPL models tend to be large-the number of products in an SPL can be exponential in the number of features. Modelling these systems poses two main challenges. Firstly, a modular modelling formalism that scales well is required. Secondly, the ability to analyse and verify complex models efficiently is key in order to ensure that all products behave correctly. The choice of a system modelling formalism that is both expressive and well-established is therefore crucial. In this paper we show how SPLs can be modelled in an incremental, modular fashion using a formal method based on Petri nets. We continue our work on Feature Petri Nets, a lightweight extension to Petri nets, by presenting a framework for modularly constructing Feature Petri Nets to model SPLs. © 2011 Springer-Verlag.