Cloud adoption: a goal-oriented requirements engineering approach

The enormous potential of cloud computing for improved and cost-effective service has generated unprecedented interest in its adoption. However, a potential cloud user faces numerous risks regarding service requirements, cost implications of failure and uncertainty about cloud providers’ ability to meet service level agreements. These risks hinder the adoption of cloud computing. We motivate the need for a new requirements engineering methodology for systematically helping businesses and users to adopt cloud services and for mitigating risks in such transition. The methodology is grounded in goal-oriented approaches for requirements engineering. We argue that Goal-Oriented Requirements Engineering (GORE) is a promising paradigm to adopt for goals that are generic and flexible statements of users’ requirements, which could be refined, elaborated, negotiated, mitigated for risks and analysed for economics considerations. The methodology can be used by small to large scale organisations to inform crucial decisions related to cloud adoption. We propose a risk management framework based on the principle of GORE. In this approach, we liken risks to obstacles encountered while realising cloud user goals, therefore proposing cloud-specific obstacle resolution tactics for mitigating identified risks. The proposed framework shows benefits by providing a principled engineering approach to cloud adoption and empowering stakeholders with tactics for resolving risks when adopting the cloud. We extend the work on GORE and obstacles for informing the adoption process. We argue that obstacles’ prioritisation and their resolution is core to mitigating risks in the adoption process. We propose a novel systematic method for prioritising obstacles and their resolution tactics using Analytical Hierarchy Process (AHP). To assess the AHP choice of the resolution tactics we support the method by stability and sensitivity analysis

Achieving Autonomic Web Service Compositions with Models at Runtime

Over the last years, Web services have become increasingly popular. It is because they allow businesses to share data and business process (BP) logic through a programmatic interface across networks. In order to reach the full potential of Web services, they can be combined to achieve specifi c functionalities. Web services run in complex contexts where arising events may compromise the quality of the system (e.g. a sudden security attack). As a result, it is desirable to count on mechanisms to adapt Web service compositions (or simply called service compositions) according to problematic events in the context. Since critical systems may require prompt responses, manual adaptations are unfeasible in large and intricate service compositions. Thus, it is suitable to have autonomic mechanisms to guide their self-adaptation. One way to achieve this is by implementing variability constructs at the language level. However, this approach may become tedious, difficult to manage, and error-prone as the number of con figurations for the service composition grows. The goal of this thesis is to provide a model-driven framework to guide autonomic adjustments of context-aware service compositions. This framework spans over design time and runtime to face arising known and unknown context events (i.e., foreseen and unforeseen at design time) in the close and open worlds respectively. At design time, we propose a methodology for creating the models that guide autonomic changes. Since Service-Oriented Architecture (SOA) lacks support for systematic reuse of service operations, we represent service operations as Software Product Line (SPL) features in a variability model. As a result, our approach can support the construction of service composition families in mass production-environments. In order to reach optimum adaptations, the variability model and its possible con figurations are verifi ed at design time using Constraint Programming (CP). At runtime, when problematic events arise in the context, the variability model is leveraged for guiding autonomic changes of the service composition. The activation and deactivation of features in the variability model result in changes in a composition model that abstracts the underlying service composition. Changes in the variability model are refl ected into the service composition by adding or removing fragments of Business Process Execution Language (WS-BPEL) code, which are deployed at runtime. Model-driven strategies guide the safe migration of running service composition instances. Under the closed-world assumption, the possible context events are fully known at design time. These events will eventually trigger the dynamic adaptation of the service composition. Nevertheless, it is diffi cult to foresee all the possible situations arising in uncertain contexts where service compositions run. Therefore, we extend our framework to cover the dynamic evolution of service compositions to deal with unexpected events in the open world. If model adaptations cannot solve uncertainty, the supporting models self-evolve according to abstract tactics that preserve expected requirements.Alférez Salinas, GH. (2013). Achieving Autonomic Web Service Compositions with Models at Runtime [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34672TESI

Definition and use of software requirement patterns in requirements engineering

The final quality of software products and services depends on the requirements stated in the Software Requirements Specifications (SRSs). However, some problems like ambiguity, incompleteness and inconsistency have been reported in the writing of SRSs, especially when natural language is used. Requirements reuse has been proposed as a key asset for requirements engineers to efficiently elicit, validate and document software requirements and, as a consequence, obtain SRSs of better quality through more effective engineering processes. Among all the possible techniques to achieve reuse, patterns hold a prominent position. In their most classical form, patterns describe problems that occur over and over again, and then describe the core of the solution to these problems. Software engineering practitioners have adopted the notion of pattern in several contexts, remarkably related to software design (e.g., design patterns and software architectural patterns), but also in other software development phases, both earlier and later. Following this strategy, requirement patterns emerge as a natural way to reuse knowledge during the Requirements Engineering (RE) stage. Although there have been several techniques proposed to reuse requirements, it has been observed that no concrete proposal has achieved a wide acceptance, neither any covered all the necessary elements to encourage organizations to adopt requirements reuse. As a consequence, this thesis proposes the use of Software Requirement Patterns (SRPs) as a means to capture and reuse requirements knowledge in the context of information technology projects. Following the typical context-problem-solution structure of patterns, an SRP mainly consists of: a template (solution) that may generate one or more requirements when applied in a certain project, and some information (context-problem) to identify its applicability in that project. To facilitate their use, SRPs are encapsulated inside the PABRE (PAttern-Based Requirements Elicitation) framework. The framework covers all the elements that could be critical for the adoption of a requirements reuse technique. Specifically, the framework includes: - A metamodel that describes the structure and semantics of SRPs and their organization inside a catalogue. - An SRP catalogue composed by non-functional, non-technical and functional SRPs, the functional ones being specific for the content management system domain. - A method for guiding the use of an SRP catalogue during requirements elicitation and specification, as well as another one for constructing and updating it. - An economic model to perform cost-benefit analysis on the adoption of SRPs based on return-on-investment. - The PABRE system as technological support. In order to analyse the benefits and drawbacks of the SRPs proposed in this thesis, two empirical studies have been carried out to investigate the perception of participants about requirement patterns in general and SRPs in particular. The first one is an exploratory survey addressed to information technology people with industrial experience in RE, which analyses the current state of the practice of requirement patterns approaches. The second one corresponds to a set of semi-structured interviews, focussed on the SRP approach, conducted to requirements engineers of Swedish organizations. Moreover, as it has been discovered that there are few empirical studies showing the state of the practice of requirements reuse in industry, the first study also explores the current situation of requirements reuse practices in organizations.La qualitat final dels productes i serveis de software depèn del requisits definits en l’especificació de Requisits Software (ERS). Tot i així, alguns problemes com la ambigüitat, incompletesa i inconsistència han sigut detectats en la escriptura dels ERS, especialment quan el llenguatge natural és usat per escriure’ls. La reutilització de requisits ha sigut proposada com un recurs clau pels enginyers de requisits per tal d’obtenir, validar i documentar requisits software i, com a conseqüència, obtenir ERS de millor qualitat usant processos d’enginyeria més efectius. Entre totes les tècniques possibles per aconseguir la reutilització, els patrons tenen una posició destacada. En la seva forma més clàssica, els patrons descriuen problemes que ocorren sovint, i després descriuen la part central de la solució a aquests problemes. Els professionals de la enginyeria del software han adoptat la noció de patró en diferents àmbits, especialment en els relacionats amb el disseny del software (per exemple, els patrons de disseny i els patrons d’arquitectura del software), però també en altres etapes del desenvolupament del software, tant abans com després del seu disseny. Seguint aquesta estratègia, els patrons de requisits emergeixen com una manera natural de reutilitzar coneixement durant l’etapa d’enginyeria de requisits. Tot i que hi ha hagut varies tècniques proposades per reutilitzar requisits, s’ha observat que no hi ha cap proposta concreta que hagi aconseguit una àmplia acceptació, ni cap proposta completa que cobreixi tots els elements necessaris per animar a les organitzacions a adoptar la reutilització de requisits. Com a conseqüència, aquesta tesis proposa l’ús de Patrons de Requisits Software (en anglès Software Requirement Patterns o SRPs) com un medi per capturar i reutilitzar coneixement de requisits en l’àmbit de projectes de tecnologia de la informació. Seguint la estructura típica dels patrons de context-problema-solució, un SRP consisteix en: una plantilla (solució) que pot generar un o més requisits quan és aplicat en un projecte específic, i informació relacionada (context-problema) per identificar la seva aplicabilitat en un projecte. Per facilitar el seu ús, els SRP han sigut encapsulats dintre del framework PABRE (de l’anglès PAttern-Based Requirements Elicitation). El framework cobreix tots els elements que podrien ser crítics per adoptar una tècnica de reutilització de requisits. Més detalladament, el framework inclou: - Un meta model que descriu la estructura i semàntica dels SRPs i la seva organització dintre d’un catàleg.Postprint (published version

The management of fire complexity at the edge of criticality

A la coberta consta: "Boosting eco-innovation for emergency, management, organizations". Aplicat embargament des de la data de defensa fins el dia 30/6/2022Fire regimes are changing under the influence of global change. On the European continent, landscape memory in the 21st century is dominated by an accumulation of forest fuel and irrupted by a progressive climatic forcing that generates a latitudinal and altitudinal escalation of wildfire generations. Catalonia, and especially the mountain areas, is located within these pyro-climatic niches where the gradients of productivity-aridity are in a situation of remarkable vulnerability. Fires in these impact areas are expected to play an ecological role of renewal with no precedents in recent history, at the expense of a high socio-ecological severity in the short-medium term, though. In the first block, the thesis analyses the probability distributions of burned areas at different space-time scales in order to better understand the statistical nature of fires in Catalonia in recent history. In line with other existing publications, the analysis demonstrates the positive impact of the fire prevention and extinction system, with a significant reduction of the potential of large fires since the beginning of the 21st century. At the same time, the analysis also shows an arched back effect in the middle range of the probability distributions, as well as a more sustained correlation in the lower range of fires, since there is a better field data collection. The analysis focuses on different space-time aggregates in Catalonia, paying special attention to the Pyrenees region. In the second block, the research effort focuses on the synthesis of a case study. Knowledge of basic research is used, previously available tools for modelling the dynamics of the landscape are adapted, and new parameters are proposed such as the ecological fire flow. Although the case study responds to a demand from the government of Aran to promote a program of prescribed burns, it is above all an explicit proposal of the Catalan Fire and Rescue Services to prototype fire management in the Pyrenees including the lessons of the community of experts as well as the concerns of public and private managers in a context of global change. The synthesis consists in integrating tactical expertise and scientific knowledge to provide a technically viable alternative (project design and project management) which in turn offers an Aran-sized modelling tool capable of integrating succession dynamics, fire regime, climatic scenarios and different alternatives of response / management, as well as of quantifying the impacts on key environmental vectors such as habitat diversity and effects on protective forests, among others. The thesis demonstrates the potential benefit of positive fire selection from the statistical analysis of the historical fire regime (the hammer effect) and the virtual experimentation (MEDFIRE Aran). On this basis, it proposes a framework of action (the pyro-sustainability) specifically adapted to the size of Aran territory which allows to deploy strategies for both the extinction and reduction of the high severity, and the use prescribed in formed burns and fire management in pre-agreed and pre-planned spaces. The general aim here is to break with the paradox of extinction and to align the resilience of the landscape with the changing climatic conditions in the medium-long term. Many scientific contributions conclude the need to change from the era of extinction to the era of regime management. The thesis precisely provides an effective methodology for sustainable coexistence with fire, applicable to the Pyrenees and other mountain massifs, which would prevent these large biodiversity pools from being left to the chance of extreme weather.Els règims de foc estant canviant sota la influència del canvi global. En el continent europeu, la memòria de paisatge en ple segle XXI està dominada per una acumulació del combustible forestal, i irrompuda per un forçament climàtic progressiu que genera un escalada latitudinal i altitudinal de les generacions d’incendi. Catalunya, i especialment les zones de muntanya, està dins d’aquests nínxols piro-climàtics on els gradients de productivitat-aridesa estan en una situació notablement vulnerable. Els incendis en aquestes zones d’impacte es preveu juguin un paper ecològic de renovació sense precedents en la història recent, a costa però d’una alta severitat socioecològica a curt-mig termini. En un primer bloc, la tesi analitza les distribucions de probabilitat d’àrees cremades a diferents escales espai-temps per tal de conèixer millor la naturalesa estadística dels incendis de Catalunya en la història recent. En la línia d’altres publicacions ja existents, l’anàlisi demostra la incidència positiva del sistema de prevenció i extinció d’incendis, havent reduït significativament el potencial dels grans incendis des de l’inici del segle XXI. Alhora, demostra també com es produeix un arqueig en les distribucions de probabilitat en la franja mitja, així com també una correlació més sostinguda en la franja baixa d’incendis. L’anàlisi es centra en diferents agregats espai-temps de Catalunya, i posa una atenció especial als Pirineus per ser la zona on es preveu una alteració major dels nínxols piro-climàtics i d’escalada de generacions d’incendi. En un segon bloc, l’esforç de recerca se centra en la síntesi d’un cas d’estudi. S’aprofiten coneixements de la recerca bàsica, s’adapten eines ja disponibles de modelització de la dinàmica del paisatge, i es proposen nous paràmetres com el cabal ecològic de foc. El cas d’estudi respon a una demanda del govern de l’Aran per impulsar un programa de cremes prescrites però sobretot, és una proposta explícita del Cos de Bombers de la Generalitat per prototipar la gestió d’incendis en massissos de muntanya incloent els aprenentatges de la comunitat d’experts, així com les inquietuds dels gestors públics i privats en un context de canvi global. La síntesi consisteix en integrar expertesa tàctica i coneixement científic per proveir una alternativa tècnicament viable, oferint també una eina de modelització a mida de l’Aran capaç d’integrar dinàmiques de successió, règim d’incendis, escenaris climàtics i diferents alternatives de resposta/gestió així com capaç de quantificar impactes sobre vectors ambientals clau com la diversitat d’hàbitats, l’afectació de boscos protectors, entre altres. La tesi demostra el benefici potencial de la selecció positiva del foc a partir de l’anàlisi estadístic del règim d’incendis històric (the hammer effect) i de l’experimentació virtual (MEDFIRE Aran). A partir d’això proposa un marc d’acció (la piro-sostenibilitat) dissenyat a mida de l’Aran, capaç de desplegar estratègies tant per l’extinció i reducció de l’alta severitat, com també per a l’ús prescrit en format cremes i de gestió d’incendis en espais pre-consensuats i pre-planificats, tot plegat amb l’objectiu de trencar amb la paradoxa de l’extinció i alinear a mig-llarg termini la resiliència del paisatge davant les condicions climàtiques canviants. Són nombroses les aportacions científiques que conclouen la necessitat de canviar de l’era de l’extinció a l’era de la gestió del règim, i en aquest sentit la tesi proporciona precisament una metodologia efectiva per la coexistència sostenible amb el foc, fent-la adaptable a escala Pirineus i en altres massissos de muntanya, i evitant d’aquesta manera deixar aquests grans espais de biodiversitat abocats a l’atzar de la meteorologia extrema.Postprint (published version