Software architecture: styles and representational schemes

Software architecture is being widely used today to describe a very high-level design methodology of large software systems. Software architecture represents the overall structure of a system in an abstract, structured manner. A good architectural representation scheme holds the key to the effectiveness of a software architecture description and usage. In this work we look at architectural styles and architectural representation schemes. We propound the idea that the layered architectural model is a suitable candidate for a generalized architectural style and that it can cater to many different problem domains, other than the message-passing systems it has traditionally been used to model. We propose some rules by which the layered architectural style can be improved and modified in order to be able to model a wider problem domain. Then we evaluate different methods of architectural representations that have been used to model software architecture and analyze their strengths and shortcomings. We propose the use of a modified data flow diagram architecture representation scheme. This scheme is called AND-OR DFD method and is introduced and developed in this thesis. The main concept introduced here is a combination of components to form action groups to support multiple workflows and the relationships among them, without significant increase in the architectural complexity. Finally, we look at UML as a prospect for a generalized architecture description language and discuss its merits and demerits with examples

Composition des modèles de lignes de produits logiciels

Cette thèse s inscrit dans le cadre de la gestion des modèles de lignes de produits logiciels complexes. L ingénierie des lignes de produits logiciels a pour objectif de modéliser et développer une famille de produits logiciels présentant un ensemble de similarités plutôt que de modéliser et développer des produits logiciels individuels au cas par cas. La modélisation, cependant, peut se révéler une tâche difficile voir même infaisable quand il s agit de modéliser des lignes de produits logiciels complexes et à grande échelle. Pour résoudre un tel problème, la tâche de modélisation est distribuée sur différents intervenants. Les modèles développés séparément doivent alors être composés pour obtenir le modèle global de la ligne de produits logiciels. Toutefois, la composition des modèles de lignes de produits logiciels n est pas une tâche triviale car elle doit prendre en compte l information de variabilité des éléments de modèles, les contraintes de variabilité, la structure des modèles manipulés et la sémantique ciblée par la composition. L objectif de cette thèse est de fournir des mécanismes de composition des modèles de lignes de produits logiciels. Pour cela, deux mécanismes sont proposés : la fusion et l agrégation. La fusion a pour objectif de combiner des modèles présentant des similarités au niveau de leurs éléments structurels. Alors que l agrégation vise à composer des modèles ne possèdent pas de similarités mais plutôt d éventuelles contraintes transversales reliant leurs éléments structurels. Les modèles utilisés sont représentés sous une vue de structures composites d UML et incluent des annotations spécifiques des éléments variables. Les mécanismes que nous proposons traitent l information de variabilité des éléments structurels manipulés, les contraintes de variabilités associées aux éléments annotés variables ainsi que l aspect structurel des modèles à composer. Les mécanismes de composition proposés sont définis selon des propriétés sémantiques bien précises décrivant le but de la composition. Ces propriétés sémantiques doivent alors être vérifiées tout au long du processus de composition. A la fin, une évaluation du travail effectué permet de montrer la capacité à composer des modèles de lignes de produits logiciels en un temps raisonnable ainsi que l importance de la consolidation des modèles structurels dans la réduction du nombre de produits structurellement incomplets.The Software Product Line (SPL) engineering aims at modeling and developing a set of software systems with similarities rather than individual software systems. Modeling task can be, however, tedious or even infeasible for large scale and complex SPLs. To address such a problem, the modeling task is distributed among different stakeholders. At the end, the models separately developed have to be composed in order to obtain the global SPL model. Composing SPL models is not a trivial task; variability information of model elements has to be treated during the composition, as well as the variability constraints. Similarly, the model structure and the composition semantics are key points that have to be considered during the composition. This thesis aims at providing specific mechanisms to compose SPL models. Therefore, we propose two composition mechanisms: the merge and the aggregation mechanisms. The merge mechanism aims at combining models including structural similarities. The aggregation mechanism, however, intends to compose models without any structural similarity but having eventual constraints across their structural elements. We focus on UML composite structures of SPLs and use specific annotations to identify variable elements. Our composition mechanisms deal with the variability information of structural elements, the variability constraints associated with the variable elements as well as the structures of the manipulated models. We also specify a set of semantic properties that have to be considered during the composition process and show how to preserve them. At the end, we have carried out an assessment of the proposals and have showed their ability to compose SPL models in a reasonable time. We have also showed how model consolidation is important in reducing le number of products having incomplete structure.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Systematic construction of goal-oriented COTS taxonomies

El proceso de construir software a partir del ensamblaje e integración de soluciones de software pre-fabricadas, conocidas como componentes COTS (Comercial-Off-The-Shelf) se ha convertido en una necesidad estratégica en una amplia variedad de áreas de aplicación. En general, los componentes COTS son componentes de software que proveen una funcionalidad específica, que están disponibles en el mercado para ser adquiridos e integrados dentro de otros sistemas de software. Los beneficios potenciales de esta tecnología son principalmente la reducción de costes y el acortamiento del tiempo de desarrollo, a la vez que fomenta la calidad. Sin embargo, numerosos retos que van desde problemas técnicos y legales deben ser afrontados para adaptar las actividades tradicionales de ingeniería de software para explotar los beneficios del uso de COTS para el desarrollo de sistemas.Actualmente, existe un incrementalmente enorme mercado de componentes COTS; así, una de las actividades más críticas en el desarrollo de sistemas basados en COTS es la selección de componentes que deben ser integrados en el sistema a desarrollar. La selección está básicamente compuesta de dos procesos principales: La búsqueda de componentes candidatos en el mercado y su posterior evaluación con respecto a los requisitos del sistema. Desafortunadamente, la mayoría de los métodos existentes para seleccionar COTS, se enfocan en el proceso de evaluación, dejando de lado el problema de buscar los componentes en el mercado. La búsqueda de componentes en el mercado no es una tarea trivial, teniendo que afrontar varias características del mercado de COTS, tales como su naturaleza dispersa y siempre creciente, cambio y evolución constante; en este contexto, la obtención de información de calidad acerca de los componentes no es una tarea fácil. Como consecuencia, el proceso de selección de COTS se ve seriamente dañado. Además, las alternativas tradicionales de reuso también carecen de soluciones apropiadas para reusar componentes COTS y el conocimiento adquirido en cada proceso de selección. Esta carencia de propuestas es un problema muy serio que incrementa los riesgos de los proyectos de selección de COTS, además de hacerlos ineficientes y altamente costosos. Esta disertación presenta el método GOThIC (Goal- Oriented Taxonomy and reuse Infrastructure Construction) enfocado a la construcción de infraestructuras de reuso para facilitar la búsqueda y reuso de componentes COTS. El método está basado en el uso de objetivos para construir taxonomías abstractas, bien fundamentadas y estables para lidiar con las características del mercado de COTS. Los nodos de las taxonomías son caracterizados por objetivos, sus relaciones son declaradas como dependencias y varios artefactos son construidos y gestionados para promover la reusabilidad y lidiar con la evolución constante.El método GOThIC ha sido elaborado a través de un proceso iterativo de investigación-acción para identificar los retos reales relacionados con el proceso de búsqueda de COTS. Posteriormente, las soluciones posibles fueron evaluadas e implementadas en varios casos de estudio en el ámbito industrial y académico en diversos dominios. Los resultados más relevantes fueron registrados y articulados en el método GOThIC. La evaluación industrial preliminar del método se ha llevado a cabo en algunas compañías en Noruega.The process of building software systems by assembling and integrating pre-packaged solutions in the form of Commercial-Off-The-Shelf (COTS) software components has become a strategic need in a wide variety of application areas. In general, COTS components are software components that provide a specific functionality, available in the market to be purchased, interfaced and integrated into other software systems. The potential benefits of this technology are mainly its reduced costs and shorter development time, while maintaining the quality. Nevertheless, many challenges ranging form technical to legal issues must be faced for adapting the traditional software engineering activities in order to exploit these benefits.Nowadays there is an increasingly huge marketplace of COTS components; therefore, one of the most critical activities in COTS-based development is the selection of the components to be integrated into the system under development. Selection is basically composed of two main processes, namely: searching of candidates from the marketplace and their evaluation with respect to the system requirements. Unfortunately, most of the different existing methods for COTS selection focus their efforts on evaluation, letting aside the problem of searching components in the marketplace. Searching candidate COTS is not an easy task, having to cope with some challenging marketplace characteristics related to its widespread, evolvable and growing nature; and the lack of available and well-suited information to obtain a quality-assured search. Indeed, traditional reuse approaches also lack of appropriate solutions to reuse COTS components and the knowledge gained in each selection process. This lack of proposals is a serious drawback that makes the whole selection process highly risky, and often expensive and inefficient. This dissertation introduces the GOThIC (Goal- Oriented Taxonomy and reuse Infrastructure Construction) method aimed at building a domain reuse infrastructure for facilitating COTS components searching and reuse. It is based on goal-oriented approaches for building abstract, well-founded and stable taxonomies capable of dealing with the COTS marketplace characteristics. Thus, the nodes of these taxonomies are characterized by means of goals, their relationships declared as dependencies among them and several artifacts are constructed and managed for reusability and evolution purposes. The GOThIC method has been elaborated following an iterative process based on action research premises to identify the actual challenges related to COTS components searching. Then, possible solutions were envisaged and implemented by several industrial and academic case studies in different domains. Successful results were recorded to articulate the synergic GOThIC method solution, followed by its preliminary industrial evaluation in some Norwegian companies