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The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-39417-6 i* is a widespread framework in the software engineering field that supports goal-oriented modeling of socio-technical systems and organizations. At its heart lies a language offering concepts such as actor, dependency, goal and decomposition. i* models resemble a network of interconnected, autonomous, collaborative and dependable strategic actors. Around this language, several analysis techniques have emerged, e.g. goal satisfaction analysis and metrics computation. In this work, we present a consolidated version of the i* language based on the most adopted versions of the language. We define the main constructs of the language and we articulate them in the form of a metamodel. Then, we implement this version and a concrete technique, goal satisfaction analys is based on goal propagation, using ADOxx. Throughout the chapter, we used an example based on open source software adoption to illustrate the concepts and test the implementation.

The process of designing a software architecture using different kinds of components is often challenging. Different designs support some quality attributes while damaging others; therefore, trade-off analysis is needed to make informed decisions. Moreover, analysis made in theory needs to be complemented with observations in practice, especially when using a particular set of technologies to implement the system. In this paper, we present a particular instance of this problem. We study how the Three-Layer architectural pattern may be developed using plug-ins. We compare two extreme alternatives according to several representative scenarios and their impact in some quality attributes. Then, we apply this theoretical knowledge to a case study, the implementation of a plug-in-based tool for managing architectural knowledge using Eclipse. We report some unexpected difficulties found that forced us to adapt the theoretical solution into an operative architecture.

iStarML is an XML-based format for enabling i* interoperability. A relevant difference with any other interoperability proposal is that iStarML is founded under the assumption that there is not a common ontology guiding this communication proposal. The different i* variants and even particular applications proposing new language constructors forced to confront a theoretical approach for supporting an interoperability approach in an evolving and variable semantic scenario. In this paper we focused on the theories behind the iStarML proposal, which include sociological, cybernetics and linguistics approaches. Finally, we apply what these theories predict to the case of the i* framework and its research community.

Multi-Stakeholder Distributed Systems (MSDS) are distributed systems in which subsets of the nodes are designed, owned, or operated by distinct stakeholders. New computing paradigms such as service-oriented computing mean that challenges posed by MSDS will be more dominant in the future. These challenges have particular implications for requirements engineering (RE). For example, in MSDS decisions about the system architecture are increasingly shifted from system design to system operation. In this paper we discuss the characteristics of MSDS and present a framework for structuring the MSDS research issues. Using an example we illustrate that existing RE approaches for goal modelling, variability modelling, and negotiation techniques can be used successfully if used in an integrated manner to address the identified challenges.

This paper presents our PABRE method for facilitating Requirements Elicitation on the basis of Requirement Patterns with the goal of saving time and reducing errors during this activity. The process presented applies for elicitation in Off-The-Shelf selection projects driven by call-for-tender processes and uses a Requirement Patterns Catalogue. The process selects patterns from the catalogue that apply to the particular selection project, and convert them into the real requirements that finally configure the project Requirements Document. We show some benefits of the pattern approach for requirements engineers and IT consultants, as well as for customers. Finally we discuss the strengths and weaknesses of the proposal and identify some future work.

This paper presents a proposal of online questionnaire whose main goals are: to know current requirements engineering practices related with essential aspects for the definition of requirement patterns and to analyze the current and potential use of patterns in industry. The target audience of the questionnaire is any practitioner or academic with different levels of experience on requirement engineering.

L'objectiu principal d'aquest projecte és evolucionar i millorar un component software encarregat del càlcul de mètriques, factors i indicadors de qualitat a partir de dades obtingudes de fonts diferents com ara gestors de projectes i gestors de versions de codi. També s'estudiarà la conveniencia de substituir el sistema d'accés i emmagatzemament d'aquestes dades. The main goal of this project is to evolve and improve a software component responsible for the calculus of metrics, factors and quality indicators from data obtained from different sources such as project management tools and version code management tools. Besides, the convenience of substituting the access and storage system of this data will be studied.

Software systems need monitors for observing them and respond to changes through adaptation. Any fault in the monitors would affect directly the systems' adaptation decisions. This project consists on implementing a monitoring system capable of detecting failures on the monitors, and apply the corre

Background: Software reference architectures are becoming widely adopted by organizations that need to support the design and maintenance of software applications of a shared domain. For organizations that plan to adopt this architecture-centric approach, it becomes fundamental to understand how software reference architectures are engineered, and to know their return on investment. Unfortunately, there is a lack of evidence-based support to help organizations with these challenges. Goal: The main goal of this PhD thesis is to support organizations making informed decisions about software reference architecture acquisition, design, and use based on empirical evidence. Methods: To accomplish this goal, we have conducted an action research approach in an industry-academia collaboration between everis (a multinational IT consulting firm based in Spain) and our Research Group of Software and Service Engineering (GESSI). Results: The results from our industry-academia collaboration led to uncover novel evidence on the use of software reference architectures in practice. The procedures and evidence obtained have been packaged to design guidelines that could be used in similar contexts as the one of everis. Conclusions: This PhD thesis supports organizations to acquire and engineer software reference architectures by providing evidence-based support. Such evidence-based support consists of the results of the empirical studies conducted in this PhD thesis, and the presented guidelines for gathering new corporate evidence. Context: Les arquitectures del software de referència estan sent àmpliament adoptades per les organitzacions que necessiten dissenyar i mantenir aplicacions software d’un domini compartit. Per les organitzacions que tenen previst adoptar aquest enfocament centrat en l’arquitectura, esdevé fonamental entendre com es dissenyen les arquitectures del software de referència, i conèixer el seu retorn d’inversió. Desafortunadament, hi ha una manca de recolzament basat en l’evidència per ajudar aquestes organitzacions a afrontar aquests reptes. Objectiu: L’objectiu principal d’aquesta tesi doctoral és recolzar les organitzacions a prendre decisions informades i basades en l’evidència empírica sobre l’adquisició, disseny i ús d’arquitectures del software de referència. Mètodes: Per aconseguir aquest objectiu, s’ha portat a terme un enfocament d’investigació-acció en una col·laboració empresa-universitat entre “everis” (una empresa multinacional de consultoria tecnològica amb seu a Espanya) i el nostre Grup d’investigació en Enginyeria del Software i Serveis (GESSI). Resultats: Fruït de la nostra col·laboració empresa-universitat, s’han descobert noves evidències sobre l’ús d’arquitectures del software de referència a la pràctica. Els procediments i les evidències obtingudes han estat empaquetades per dissenyar directrius que podrien ser utilitzades en contextos similars com el d’everis. Conclusions: Aquesta tesi doctoral és una contribució per les organitzacions que adopten i dissenyen arquitectures del software de referència, proporcionant recolzament basat en l’evidència empírica. Aquest recolzament es constitueix dels resultats dels estudis empírics realitzats en aquesta tesi doctoral, i les directrius que es presenten per la recol·lecció de noves evidències corporatives.

Service Oriented Computing (SOC) has been established in the last recent years as a successful paradigm in Software Engineering. The systems built under this paradigm, known as Service Based System (SBS), are composed of several services, which are usually third-party software run by external service providers. SBS rely on these service providers to ensure that their services comply with the agreed Quality of Service (QoS). In contrast to other systems, the dynamic behaviour of SBS requires up-to-date QoS information for its proper management in the different stages of its lifecycle, from their initial construction until their decommission. Providing such QoS information has resulted in different technological solutions built around a monitor. Nonetheless, several research challenges in the field remain still open, ranging from theoretical aspects of quality assurance to architectonical challenges in decentralized monitoring. Based on the current research challenges for service monitoring, the research gaps in which we aim to contribute are twofold: - To investigate on the definition and structure of the different quality factors of services, and provide a framework of common understanding for the definition of what to monitor. - To investigate on the different features required to support the activities of the whole SBS lifecycle (i.e. how to monitor), and develop a monitoring framework that accomplishes such features. As a result of this thesis, we provide: What to monitor - A distribution of the quality models along the time dimension and the identification of their relationships. - An analysis of the size and definition coverage of the proposed quality models. - A quantified coverage of the different ISO/IEC 25010 quality factors given by the proposals. - The identification of the most used quality factors, and provided the most consolidated definitions for them. How to monitor - The elicitation of the requirements of the different activities in the SBS lifecycle. - The definition of the set of features that supports the elicited requirements. - A modular service-oriented monitoring framework, named SALMon, implementing the defined features. SALMon has been validated by including it in several frameworks supporting the different activities of the SBS lifecycle. Finally, we have conducted a performance evaluation of SALMon over real web services., La Computació Orientada a Serveis (SOC) ha esdevingut en els darrers anys un paradigma exitós en el camp de l'Enginyeria del Software. Els sistemes construïts sota aquest paradigma, coneguts com Sistemes Basats en Serveis (SBS), estan composats de diversos serveis, que són, usualment, programari de tercers executats per proveïdors de serveis externs. Els SBS depenen dels proveïdors dels serveis per garantir que els serveis compleixen amb la Qualitat del Servei (QoS) acordada. En contrast amb altres sistemes, el comportament dinàmic dels SBS requereix d'informació actualitzada del QoS per a la correcta administració de les diferents etapes del cicle de vida dels SBS: des de la seva construcció inicial fins a la seva clausura. Proveir d'aquesta informació de QoS ha resultat en diferents solucions tecnològiques construïdes al voltant d'un monitor. Malgrat això, diversos reptes de recerca en el camp encara romanen obertes, des d'aspectes teòrics de l'assegurança de qualitat, a reptes arquitectònics en la monitorització descentralitzada. Basat en els reptes de recerca actuals per a la monitorització de serveis, els forats de recerca en els que pretenem contribuir són dobles: - Investigar en la definició i estructura dels diferents factors de qualitat dels serveis, i proveir un marc de treball d'entesa comuna per a la definició de què monitoritzar. - Investigar en les diferents característiques requerides per donar suport a les activitats de tot el cicle de vida dels SBS (i.e. com monitoritzar), i desenvolupar una plataforma de monitorització que acompleixi aquestes característiques. Com a resultats de la tesis, proveïm: Què monitoritzar - Una distribució dels models de qualitat al llarg de la dimensió temporal i la identificació de les seves interrelacions. - Un anàlisi de la mida i definició de la cobertura dels models de qualitat proposats. - Una cobertura quantificada dels diferents factors de qualitat ISO/IEC 25010 donat en les diferents propostes. - La identificació dels factors de qualitat més utilitzats, i la definició dels termes més consolidats. Com monitoritzar - L'elicitació dels requeriments per a les diferents activitats en el cicle de vida dels SBS. - La definició del conjunt de característiques que donen suport als requeriments elicitats. - Una platforma modular orientada a serveis, anomenat SALMon, que implementa les característiques definides. SALMon ha estatvalidat incloent la plataforma en diversos marcs de treball donant suport a les diferents activitats

In the last decades, software engineering has become an important area of research. As researchers, we try to identify a problem, a need, or a hole in some research topic, once identified we make an effort to produce new techniques, methods, and tools that hopefully will help to improve the detected issue. In the present thesis the identified issue was the need of supporting non-functional requirements in the software architecture design where these requirements are the drivers of the architectural decision-making. This thesis started with the idea that a relatively new software engineering discipline, model-driven development, was a good place to propose a solution for the detected issue. We envisioned how non-functional requirements can be integrated in model-driven development and how this integration will impact in the architectural design activities. When we started to produce our techniques, methods, and tools for model-driven development we found out that there was a bigger hole in the web of knowledge than what we had initially foreseen. Much of the evidence of how non-functional requirements affect the software architecture design is hidden. This situation caused a turn in this thesis: we needed to understand architects, how they think and how they make the architectural decisions, what is the role of non-functional requirements in the architectural decision-making process, and to what extent are the non-functional requirements important in this process. All these questions needed an answer, an answer that only architects could provide. In consequence we opted to drove several empirical studies to answer these questions. In parallel, we started to work in a way of representing this knowledge, an ontology for software architecture that integrates non-functional requirements. Using this ontology as basis, we designed a method to assist architects in the architectural decision-making process and a tool that acted as a proof of concept of both, the ontology and the method. In summary, this thesis explores how non-functional requirements are currently integrated in the software architecture design practices, and proposes ways to improve this integration and facilitate the work of architects by providing means to assist them in the architectural decision-making process.

In the last decades, software engineering has become an important area of research. As researchers, we try to identify a problem, a need, or a hole in some research topic, once identified we make an effort to produce new techniques, methods, and tools that hopefully will help to improve the detected issue. In the present thesis the identified issue was the need of supporting non-functional requirements in the software architecture design where these requirements are the drivers of the architectural decision-making. This thesis started with the idea that a relatively new software engineering discipline, model-driven development, was a good place to propose a solution for the detected issue. We envisioned how non-functional requirements can be integrated in model-driven development and how this integration will impact in the architectural design activities. When we started to produce our techniques, methods, and tools for model-driven development we found out that there was a bigger hole in the web of knowledge than what we had initially foreseen. Much of the evidence of how non-functional requirements affect the software architecture design is hidden. This situation caused a turn in this thesis: we needed to understand architects, how they think and how they make the architectural decisions, what is the role of non-functional requirements in the architectural decision-making process, and to what extent are the non-functional requirements important in this process. All these questions needed an answer, an answer that only architects could provide. In consequence we opted to drove several empirical studies to answer these questions. In parallel, we started to work in a way of representing this knowledge, an ontology for software architecture that integrates non-functional requirements. Using this ontology as basis, we designed a method to assist architects in the architectural decision-making process and a tool that acted as a proof of concept of both, the ontology and the method. In summary, this thesis explores how non-functional requirements are currently integrated in the software architecture design practices, and proposes ways to improve this integration and facilitate the work of architects by providing means to assist them in the architectural decision-making process.

This thesis provides a formal proposal for the specialization relationship in the i* framework that allows its use in a well-defined manner. I root my proposal over existing works in different areas that are interested in representing knowledge: knowledge representation from Artificial Intelligence and conceptual modeling and object-oriented programming languages from Software Development. Also, I use the results of a survey conducted in the i* community that provides some insights about what i* modelers expect from specialization. As a consequence of this twofold analysis, I identify three specialization operations: extension, refinement and redefinition. For each of them, I: - motivate its need and provide some rationale; - distinguish the several cases that can occur in each operation; - define the elements involved in each of these cases and the correctness conditions that must be fulfilled; - demonstrate by induction the fulfilment of the conditions identified for preserving satisfaction; - provide some illustrative examples in the context of an exemplar about travel agencies and travelers. The specialization relationship is offered by the i* framework through the is-a construct defined over actors (a subactor is-a superactor) since it was first released. Although the overall meaning of this construct is highly intuitive, its effects at the level of intentional elements and dependencies are not always clear, hampering seriously its appropriate use. In order to be able to reason about correctness and satisfaction, I define previously the conditions that must be preserved when a specialization takes place. In addition, I provide a methodology with well-defined steps that contextualize the formal aspects of this thesis in a development process. As a conclusion, this thesis is making possible the use of the specialization relationship in i* in a precise, non-ambiguous manner.

Since the i* framework emerged in the requirements engineering community in the mid-90s, different research groups have proposed variations to the modelling language proposed in the i* framework (¿the i* language¿). There are basically two reasons behind this fact: ¿ The definition of the i* language is loose in some parts, and some groups have opted by different solutions or proposed slight changes to the original definition. ¿ Some groups have used the i* framework with very different purposes, thus different concepts have become necessary, many of them have added their own modelling constructs. As a consequence, several i* variations at different maturity levels have been produced. The adaptability of i* to different needs is part of its own nature, therefore these variations are not to be considered pernicious, on the contrary, flexibility may be considered one of the framework¿s key success features. In this context, the objective of this thesis is to tackle the i* Interoperability Problem: to propose a framework to understand the variations of the i* modelling language and, considering this framework, to generate a proposal to support the interoperability and integration of these variations. To do so, the PhD thesis has identified and solved up to ten research questions related to the following categories: 1) The i* variants have been identified and characterized. Metamodels have been used to align these variants and identify an appropriate kernel. A critical look on the ¿why¿ this happened has been conducted from several perspectives. 2) An interoperability framework in terms of metamodel alignment has been formulated. This interoperability framework has come from the adaptation of a solution to metamodel evolution and model co-adaptation formulated in the domain of model-driven engineering. 3) An XML-based interoperability format implementing the framework, iStarML, has been deployed. 4) The solution has been validated in terms of community acceptance by means of an empirical study, and from a practical point of view by the interconnection of different existing tools. The set of related publications shows the research path, starting from the identification and characterization of the interoperability problem, pass trhought a theoretical explanation that sustaints a technical proposal, and ends illustrating inteoperation cases and its community acceptation.