Run-time Support to Manage Architectural Variability Speci ed with CVL

The execution context in which pervasive systems or mobile computing run changes continuously. Hence, applications for these systems should be adapted at run-time according to the current context. In order to implement a context-aware dynamic reconfiguration service, most approaches usually require to model at design-time both the list of all possible configurations and the plans to switch among them. In this paper we present an alternative approach for the automatic run-time generation of application configurations and the reconfiguration plans. The generated configurations are optimal regarding di erent criteria, such as functionality or resource consumption (e.g. battery or memory). This is achieved by: (1) modelling architectural variability at design-time using Common Variability Language (CVL), and (2) using a genetic algorithm that finds at run-time nearly-optimal configurations using the information provided by the variability model. We also specify a case study and we use it to evaluate our approach, showing that it is efficient and suitable for devices with scarce resources.Campus de Excelencia Internacional Andalucia Tech y proyectos de investigación TIN2008-01942, P09-TIC-5231 and INTER-TRUST FP7-317731

Green Security Plugin for Pervasive Computing using the HADAS toolkit

Energy is a critical resource in pervasive computing devices. However, information about energy consumption is not directly accessible through software development environments, making it difficult to reuse the knowledge provided by existing energy-consumption experimental studies. To address this limitation, this paper presents a solution to enrich Android Studio with energy consumption information. We have developed a Green Security Plugin that provides energy-aware information to developers that make use of Android Security API. This plugin has been developed taking advantage of the functionalities provided by the HADAS toolkit. HADAS is a repository of energy consuming concerns in which researchers can store the energy measures obtained during their experimental studies and developers can perform a sustainability analysis to make green design/implementation decisions.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

HADAS: Asistente de eco-eficiencia con repositorio de consumo energético

El interés por la Ingeniería del Software "verde", o sea, sensible al consumo de energía, es relativamente reciente. Su objetivo es concienciar a los desarrolladores de software de la influencia que tienen sus decisiones de diseño e implementación en el gasto energético del producto final. Hasta el momento se han publicado muchos resultados experimentales que comparan el consumo de energía de varias soluciones alternativas, y que demuestran que se puede reducir dicho consumo hasta en un 70 %. Aunque estos resultados sean de libre disposición, no es sencillo que un desarrollador aplique este conocimiento a sus aplicaciones. En consecuencia, en este artículo presentamos el eco-asistente HADAS cuya utilidad es: (i) los investigadores almacenarán sus resultados en un repositorio de libre disposición; (ii) los desarrolladores podrán razonar y obtener las configuraciones que menos energía consuman y que satisfaga sus requisitos. Nos centraremos en mostrar los elementos principales de nuestra propuesta y como se aplica a casos de estudio reales.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Proyectos MAGIC P12-TIC1814 y HADAS TIN2015-64841-

Evolución arquitectónica de servicios basada en modelos CVL con cardinalidad

La computación en la nube se está convirtiendo en un mecanismo predominante para desplegar fácilmente aplicaciones con requisitos especiales, tales como el almacenamiento masivo compartido, o el equilibrado de carga. Esta funcionalidad se proporciona normalmente como servicios por las plataformas en la nube. Un desarrollador puede mejorar tanto el despliegue de sus aplicaciones como la productividad siguiendo un enfoque multi-tenancy, donde diferentes variantes de la misma aplicación pueden adaptarse rápidamente a las necesidades de cada usuario (tenant). Sin embargo, gestionar la variabilidad inherente a las aplicaciones multi-tenant, con cientos de usuarios y miles de configuraciones arquitectónicas diferentes, puede llegar a ser una tarea intratable de abordar manualmente. En este artículo, se propone un enfoque de línea de producto software en el cual: (1) usamos modelos de variabilidad con cardinalidad para modelar cada tenant como una característica clonable, (2) automatizamos el proceso de evolución de las arquitecturas de aplicaciones multi-tenant, y (3) demostramos que la implementación de los procesos de evolución es correcta y eficiente para un número elevado de tenants en un tiempo razonable.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Configuración Eco-Eficiente de Atributos de Calidad Funcionales

Los atributos de calidad funcionales (FQAs) son aquellos que para satisfacerlos se necesita incorporar funcionalidad adicional a la arquitectura de las aplicación (e.g., seguridad). La nueva funcionalidad incorporada por estos FQAs (e.g., encriptación) afecta a otro atributo de calidad como es el consumo de energía de la aplicación. Hasta el momento no se han explorado suficientemente las interdependencias entre, por ejemplo diferentes niveles de seguridad y su incidencia en el consumo de energía. En este artículo se propone una solución para ayudar al arquitecto software a generar la cofiguración de los FQAs que optimiza la ficiencia energética de la aplicación. Para ello se dfine un modelo de uso para cada FQA, teniendo en cuenta las variables que influyen en el consumo de energía y como el valor de estas variables cambia en función del punto de la aplicación donde se requiere ese FQA. Se extiende una Línea de Productos Software que modela una familia de FQAs para incorporar la variabilidad del modelo de uso y los frameworks existentes que implementan los FQAs. Generamos la configuración más eco-eficiente seleccionando el framework y las características más adecuadas para cada FQA y configurándolo según los requisitos de la aplicación.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Product Line Architecture for Automatic Evolution of Multi-Tenant Applications

Cloud computing is becoming the predominant mechanism to seamlessly deploy applications with special requirements such as massive storage sharing or load balancing, usually provided as services by cloud platforms. A developer can improve the application’s delivery and productivity by following a multi tenancy approach, where variants of the same application can be quickly customized to the necessities of each tenant. However, managing the inherent variability existing in multitenant applications and, even more importantly, managing the evolution of a multi-tenant application with hundreds of tenants and thousands of different valid architectural configurations can become intractable if performed manually. In this paper we propose a product line architecture approach in which: (1) we use cardinality-based variability models to model each tenant as a clonable feature, (2) we automate the process of evolving the multi-tenant application architecture, and (3) we demonstrate that the implemented process is correct and efficient for a high number of tenants in a reasonable time. We use a running case study in the domain of medical software.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

vEXgine: extendiendo el motor de ejecución de CVL

El Lenguaje CVL (Common Variability Language) carece de una herramienta flexible que permita poner en práctica las necesidades industriales del modelado de la variabilidad en Líneas de Producto Software. Las herramientas existentes que proporcionan soporte para CVL son prototipos incompletos, o se centran principalmente en la especificación de la variabilidad, sin llegar a resolverla sobre modelos reales. Además, no existe una API que permita la interacción directa con el motor CVL para extenderlo o usarlo en una aplicación independiente. Este artículo presenta vEXgine, una implementación adaptable y extensible del motor de ejecución de la variabilidad de CVL.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Proyectos MAGIC P12-TIC1814 y HADAS TIN2015-64841-

Run-time Adaptation of Mobile Applications using Genetic Algorithms

Mobile applications run in environments where the context is continuously changing. Therefore, it is necessary to provide support for the run-time adaptation of these applications. This support is usually achieved by middleware platforms that offer a context-aware dynamic reconfiguration service. However, the main shortcoming of existing approaches is that both the list of possible configurations and the plans to adapt the application to a new configuration are usually specified at design-time. In this paper we present an approach that allows the automatic generation at run-time of application configurations and of reconfiguration plans. Moreover, the generated configurations are optimal regarding the provided functionality and, more importantly, without exceeding the available resources (e.g. battery). This is performed by: (1) having the information about the application variability available at runtime using feature models, and (2) using an genetic algorithm that allows generating an optimal configuration at runtime. We have specified a case study and evaluated our approach, and the results show that it is efficient enough as to be used on mobile devices without introducing an excessive overhead.Campus de Excelencia Andalucía Tech y Proyectos de investigación TIN2008-01942, P09-TIC-5231 y INTER-TRUST FP7-317731

Variability Models for Generating Efficient Configurations of Functional Quality Attributes

Quality attributes play a critical role in the architecture elicitation phase. Software Sustainability and energy efficiency is becoming a critical quality attribute that can be used as a selection criteria to choose from among different design or implementation alternatives. This paper presents a process that helps developers to automatically generate optimum configurations of functional quality attributes in terms of energy efficiency and performance. Functional quality attributes refer to the behavioral properties that need to be incorporated inside a software architecture to fulfill a particular quality attribute (e.g., encryption and authentication for the security quality attribute, logging for the usability quality attribute). Quality attributes are characterized to identify their design and implementation variants and how the different configurations influence both energy efficiency and performance. A usage model for each characterized quality attribute is defined. The variability of quality attributes, as well as the energy efficiency and performance experiment results, are represented as a constraint satisfaction problem with the goal of formally reasoning about it. Then, a configuration of the selected functional quality attributes is automatically generated, which is optimum with respect to a selected objective function. Software developers can improve the energy efficiency and/or performance of their applications by using our approach to perform a richer analysis of the energy consumption and performance of different alternatives for functional quality attributes. We show quantitative values of the benefits of using our approach and discuss the threats to validity. The process presented in this paper will help software developers to build more energy efficient software, whilst also being aware of how their decisions affect other quality attributes, such as performance.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Uniform Random Sampling Product Configurations of Feature Models That Have Numerical Features

Analyses of Software Product Lines (SPLs) rely on automated solvers to navigate complex dependencies among features and find legal configurations. Often these analyses do not support numerical features with constraints because propositional formulas use only Boolean variables. Some automated solvers can represent numerical features natively, but are limited in their ability to count and Uniform Random Sample (URS) conigurations, which are key operations to derive unbiased statistics on configuration spaces. Bit-blasting is a technique to encode numerical constraints as propositional formulas. We use bit-blasting to encode Boolean and numerical constraints so that we can exploit existing #SAT solvers to count and URS conigurations. Compared to state-of-art Satisfiability Modulo Theory and Constraint Programming solvers, our approach has two advantages: 1) faster and more scalable coniguration counting and 2) reliable URS of SPL configurations. We also show that our work can be used to extend prior SAT-based SPL analyses to support numerical features and constraints.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech