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Software solutions to automate the procurement of web services are gaining importance when technology evolves, the number of providers increases and the needs of the clients become more complex. There are several proposals in this field, but they all have important drawbacks, namely: many of them are not able to check offers and demands for internal consistency; selecting the best offer usually relies on evaluating linear objective functions, which is quite a naive solution; the language to express offers is usually less expressive than the language to express demands; and, last but not least, providers cannot impose constraints on their clients. In this article, we present a solution to overcome these problems that relies on constraint programming; furthermore, we present a run-time framework, some experimental results, and a comparison with other proposals.

Context. Many reports support the fact that some psycho-social aspects of software engineers are key factors for the quality of the software development process and its resulting products. Based on the experience of some of the authors after more than a year of practising mindfulness-a meditation technique aimed to increase clearness of mind and awareness-we guessed that it could be interesting to empirically evaluate whether mindfulness affects positively not only the behaviour but also the professional performance of software engineers.Goal. In this paper, we present a quasi-experiment carried out at the University of Seville to evaluate whether Software Engineering & Information Systems students enhance their conceptual modelling skills after the continued daily practice of mindfulness during four weeks.Method. Students were divided into two groups: one group practised mindfulness, and the other-the control group-were trained in public speaking. In order to study the possible cause-and-effect relationship, effectiveness (the rate of model elements correctly identified) and efficiency (the number of model elements correctly identified per unit of time) of the students developing conceptual modelling exercises were measured before and after taking the mind-fulness and public speaking sessions.Results. The experiment results have revealed that the students who practised mindfulness have become more efficient in develop-ing conceptual models than those who attended the public speaking sessions. With respect to effectiveness, some enhancement have been observed, although not as significant as in the case of efficiency.Conclusions. This rising trend in effectiveness suggests that the number of sessions could have been insufficient and that a longer period of sessions could have also enhanced effectiveness significantly.

Abstract

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Web services bring programmers a new way to develop advanced applications able to integrate any group of services on the Internet into a single solution. Web services procurement (WSP) is focussed on the acquisition of web services, including some complex tasks such as the specification of demands, the search for available offers, and the best choice selection. Although the technology to support them already exists, there are only a few approaches wherein qualityof-service in demands and offers is taken into account, in addition to functionality. In this paper, we present some implementation issues on a quality-aware approach to WSP, whose solution is mainly based on using mathematical constraints to define quality-of-service in demands and offers.

In a literature review on the last 20 years of automated analysis of feature models, the formalization of analysis operations was identified as the most relevant challenge in the field. This formalization could provide very valuable assets for tool developers such as a precise definition of the analysis operations and, what is more, a reference implementation, i.e. a trustworthy, not necessarily efficient implementation to compare different tools outputs. In this article, we present the FLAME framework as the result of facing this challenge. FLAME is a formal framework that can be used to formally specify not only feature models, but other variability modeling languages (VMLs) as well. This reusability is achieved by its two-layered architecture. The abstract foundation layer is the bottom layer in which all VMLindependent analysis operations and concepts are specified. On top of the foundation layer, a family of characteristic model layers-one for each VML to be formally specifiedcan be developed by redefining some abstract types and relations. The verification and validation of FLAME has fol- lowed a process in which formal verification has been performed traditionally by manual theorem proving, but validation has been performed by integrating our experience on metamorphic testing of variability analysis tools, something that has shown to be much more effective than manuallydesigned test cases. To follow this automated, test-based validation approach, the specification of FLAME, written in Z, was translated into Prolog and 20,000 random tests were automatically generated and executed. Tests results helped to discover some inconsistencies not only in the formal specification, but also in the previous informal definitions of the analysis operations and in current analysis tools. After this process, the Prolog implementation of FLAME is being used as a reference implementation for some tool developers, some analysis operations have been formally specified for the first time with more generic semantics, and more VMLs are being formally specified using FLAME.

Process performance indicators (PPIs) allow the quantitative evaluation of business processes, providing essential information for decision making. It is common practice today that business processes and PPIs are usually modelled separately using graphical notations for the former and natural language for the latter. This approach makes PPI definitions simple to read and write, but it hinders maintenance consistency between business processes and PPIs. It also requires their manual translation into lower-level implementation languages for their operationalisation, which is a time-consuming, error-prone task because of the ambiguities inherent to natural language definitions. In this article, VISUAL PPINOT, a graphical notation for defining PPIs together with business process models, is presented. Its underlying formal metamodel allows the automated processing of PPIs. Furthermore, it improves current state-of-the-art proposals in terms of expressiveness and in terms of providing an explicit visualisation of the link between PPIs and business processes, which avoids inconsistencies and promotes their co-evolution. The reference implementation, developed as a complete tool suite, has allowed its validation in a multiple-case study, in which five dimensions of VISUAL PPINOT were studied: expressiveness, precision, automation, understandability, and traceability.