A framework to identify primitives that represent usability within Model-Driven Development methods

Context: Nowadays, there are sound methods and tools which implement the Model-Driven Development approach (MDD) satisfactorily. However, MDD approaches focus on representing and generating code that represents functionality, behaviour and persistence, putting the interaction, and more specifically the usability, in a second place. If we aim to include usability features in a system developed with a MDD tool, we need to extend manually the generated code. Objective: This paper tackles how to include functional usability features (usability recommendations strongly related to system functionality) in MDD through conceptual primitives. Method: The approach consists of studying usability guidelines to identify usability properties that can be represented in a conceptual model. Next, these new primitives are the input for a model compiler that generates the code according to the characteristics expressed in them. An empirical study with 66 subjects was conducted to study the effect of including functional usability features regarding end users' satisfaction and time to complete tasks. Moreover, we have compared the workload of two MDD analysts including usability features by hand in the generated code versus including them through conceptual primitives according to our approach. Results: Results of the empirical study shows that after including usability features, end users' satisfaction improves while spent time does not change significantly. This justifies the use of usability features in the software development process. Results of the comparison show that the workload required to adapt the MDD method to support usability features through conceptual primitives is heavy. However, once MDD supports these features, MDD analysts working with primitives are more efficient than MDD analysts implementing these features manually. Conclusion: This approach brings us a step closer to conceptual models where models represent not only functionality, behaviour or persistence, but also usability features. (C) 2014 Elsevier B.V. All rights reserved.This work was developed with the support of the Spanish Ministry of Science and Innovation Project SMART ADAPT (TIN201342981-P), TIN2011-23216 and was co-financed by ERDF. It also has the support of Generalitat Valenciana-funded ORCA Project (PROMETEO/2009/015) and UV (UV-INV-PRECOMP13-115032).Panach Navarrete, JI.; Juristo, N.; Valverde Giromé, F.; Pastor López, O. (2015). A framework to identify primitives that represent usability within Model-Driven Development methods. Information and Software Technology. (58):338-354. https://doi.org/10.1016/j.infsof.2014.07.002S3383545

Design and programming patterns for implementing usability functionalities in web applications

This is the author’s version of a work that was accepted for publication in Journal of Systems and Software. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Systems and Software, VOL 105, (2015) DOI 10.1016/j.jss.2015.04.023Usability is a software system quality attribute. There are usability issues that have an impact not only on the user interface but also on the core functionality of applications. In this paper, three web applications were developed to discover patterns for implementing two usability functionalities with an impact on core functionality: Abort Operation and Progress Feedback. We applied an inductive process in order to identify reusable elements to implement the selected functionalities. For communication purposes, these elements are specified as design and programming patterns (PHP, VB.NET and Java). Another two web applications were developed in order to evaluate the patterns. The evaluation explores several issues such as ease of pattern understanding and ease of pattern use, as well as the final result of the applications. We found that it is feasible to reuse the identified solutions specified as patterns. The results also show that usability functionalities have features, like the level of coupling with the application or the complexity of each component of the solution, that simplify or complicate their implementation. In this case, the Abort Operation functionality turned out to be more feasible to implement than the Progress Feedback functionality.This research has been funded by the Spanish Ministry of Science and Innovation “Tecnologías para la Replicación y Síntesis de Experimentosen IS” (TIN2011-23216) and “Go Lite” (TIN2011-24139) projects

An MDD-based method for building context-aware applications with high reusability

Adding context-awareness capabilities to modern mobile and pervasive computing applications is becoming a mainstream activity in the software engineering community. In this respect, many context models and middleware architectures have been proposed with the aim to provide the developers with tools and abstractions that make it easier to produce context-aware applications. However, current solutions suffer from relatively low reusability and lack ease-of-use. In this paper, we propose a two-layer approach based on model-driven development: at the higher layer we introduce the design of reusable context plug-ins which can be used to monitor low-level context data and to infer higher-level information about the users, their computing infrastructure and their interaction. At the lower layer, the plug-ins themselves are synthesized using more elementary, reusable components. We argue that this development approach provides significant advantages to the developers, as it enables them to design, implement, re-use and maintain the code-base of context-aware apps more efficiently. To evaluate this approach, we demonstrate it in the context of a two-part case-study and assess it both qualitatively and quantitatively

Usability Improvement Through A/B Testing and Refactoring

Usability evaluation is an essential task in web application development. There have been several attempts to integrate user-centered design with agile methods, but it is hard to synchronize their practices. User testing is very valuable to learn from feedback of actual use, but it remains expensive to find and solve usability problems. Furthermore, the high cost of usability evaluation forces small/medium-sized companies to trust the first solution applied, without actually testing the success of the solution or considering a possible regression in usability, as could be highlighted by an iterative testing method. In this article we advocate for a usability improvement cycle oriented by user feedback, and compatible with an agile development process. We propose an iterative method supported by a toolkit that allows usability experts to design user tests, run them remotely, analyze results, and assess alternative solutions to usability problems similarly to A/B testing. Each solution is created by applying client-side web refactorings, i.e., changes to the web pages in the client which are meant to improve usability. The main benefit of our approach is that it reduces the overall cost of user testing and particularly, A/B testing, by applying refactorings to create alternative solutions without modifying the application’s server code. By making it affordable for usability experts to apply the method in parallel with the development cycle, we aim to encourage them to incorporate user feedback and try different ideas to discover the best performing solution in terms of the metrics of interest.Laboratorio de Investigación y Formación en Informática Avanzad

Self-Refactoring: mejoras automáticas de usabilidad para aplicaciones web

La usabilidad en las aplicaciones web es un aspecto fundamental, pero en muchos casos relegado por diferentes motivos como la falta de personal experimentado, o los altos costos. Si bien las grandes compañías suelen estar preparadas para dedicar los recursos necesarios a mejorar la usabilidad de sus aplicaciones, las pequeñas y medianas suelen utilizarlos en otros aspectos. Para ayudar a bajar estos costos, han surgido herramientas que definición y ejecución remota de pruebas de usabilidad, o recolección de estadísticas de forma automatizada, pero igualmente se requiere de expertos que diseñen las pruebas, interpreten los reportes o visualizaciones en busca de problemas, y diseñen soluciones a los mismos, que los desarrolladores deberán implementar. En este trabajo se propone un enfoque para hallar problemas de usabilidad automáticamente en aplicaciones web, basados en el análisis de eventos de interacción de usuarios finales. Para cada uno de estos problemas de usabilidad encontrados, existe además una solución que puede sugerirse para resolver el problema. En algunos casos, es incluso posible aplicar estas soluciones automáticamente. En este enfoque, los problemas de usabilidad se definen como “usability smells” y las soluciones como “usability refactorings”, ambos términos adaptados de la jerga del refactoring de código. Los usability smells, en este contexto, son problemas que afectan la interacción por parte de los usuarios finales, mientras que los usability refactorings son transformaciones que aplican soluciones documentadas para resolver esos problemas. Como prueba de concepto se implementó Kobold: una herramienta capaz de realizar todo lo que se propone en este trabajo. La herramienta funciona como un servicio (SaaS – Software as a Service), y no requiere de casi ningún esfuerzo de instalación. Al incorporar Kobold en una aplicación web, se comienza a capturar la interacción de los usuarios, y los reportes de problemas se muestran apenas un número suficiente de usuarios se topa con los mismos. Como los usability smells son problemas bien descritos, pueden ser interpretados por cualquier desarrollador, aunque no tenga experiencia en usabilidad. De la misma forma, los refactorings que se sugieren como solución pueden ser aplicados automáticamente y en producción, gracias a la implementación de refactorings del lado del cliente, que permiten alterar la aplicación sin modificar su código. De esta manera, Kobold se presenta como una herramienta que puede resultar de utilidad tanto para desarrolladores como para expertos en usabilidad. En resumen, lo que se quiere obtener con Kobold es, como mínimo, una herramienta confiable que con un mínimo esfuerzo de configuración pueda rápidamente comenzar a brindar asesoramiento sobre usabilidad en aplicaciones que ya se encuentran corriendo en producción, y que pueda ser configurada para detectar diferentes tipos de problemas. La audiencia para esta herramienta sería de desarrolladores con experiencia en usabilidad, que quisieran tener un panorama rápido de las interacciones reales que realiza la masa de usuario, y probablemente reparar rápidamente algunos de estos problemas del lado del cliente. Más aun, esto allanaría el camino para conseguir un objetivo más ambicioso: un mecanismo confiable que permita la auto-reparación de aplicaciones web, que incluso los desarrolladores sin experiencia en usabilidad puedan utilizar para corregir los usability smells en sus aplicaciones. El trabajo presentado incluye validaciones empíricas que comprueban la factibilidad del enfoque y su implementación en todas las etapas: captura de eventos de interacción, detección de usability smells y aplicación de usability refactorings.Facultad de Informátic