Viewpoints and goals: towards an integrated approach

Dissertação de Mestrado em Engenharia InformáticaRequirements elicitation and analysis have been studied according to several approaches that differ mostly on their "orientation", in this case relying on goals or viewpoints. Goal-Oriented approaches such as KAOS rely on goals to direct their process of eliciting requirements: a goal is an objective the system under consideration should achieve and represents a system property that may reflect either a functional (e.g. a service provided by the system) or a non-functional (e.g. security, performance) requirement; its satisfaction may imply the participation of several agents and the resolution of possible obstacles that may arise. The KAOS approach offers an unambiguous method for requirement decomposition and may provide a set of heuristics to approaches where one does not exist. Viewpoint-Oriented approaches such as PREview focus on gathering information pertaining to the problem from several agents that may have different, often equally valid, and incomplete perspectives on the problem. These partial intakes reflect their different responsibilities, roles, goals, or interpretations of the information sources; hence the combination of the agent and its input on the system is called a viewpoint. PREview benefits from a particularly lightweight approach to requirements encapsulation, but fails to provide a set of heuristics for the process of identifying the system's requirements. Considering the issues identified in each approach, it is verifiable that both approaches are complementary: on the one hand, KAOS offers a set of requirements elicitation heuristics through goal decomposition; on the other hand, PREview is a lightweight approach to viewpoint oriented requirements engineering, tailored especially for integration, however lacks a more systematic mechanism to guide the requirements elicitation process. The objective of this dissertation is therefore to propose a hybrid approach that builds on the PREview approach and brings together the benefits of the KAOS approach. The result is synergetic where, for example, completion is better addressed by providing a set of heuristics for requirement elicitation

Mastering the requirements analysis for communication-intensive websites

Web application development still needs to employ effective methods to accommodate some distinctive aspects of the requirements analysis process: capturing high-level communication goals, considering several user profiles and stakeholders, defining hypermedia-specific requirements (concerning navigation, content, information structure and presentation aspects), and reusing requirements for an effective usability evaluation. Techniques should be usable by both stakeholders and the design team, require little training effort, and show relative advantage to project managers. Over the last few years, requirements methodologies applied to web-based applications have considered mainly the transactional and operational aspects typical of traditional information systems. The communicational aspects of web sites have been neglected in regards to systematic requirements methods. This thesis, starting from key achievements in Requirements Engineering (hereafter RE), introduces a model (AWARE) for defining and analyzing requirements for web applications mainly conceived as strategic communication means for an institution or organization. The model extends traditional goal and scenario-based approaches for refining highlevel goals into website requirements, by introducing the analysis of ill-defined user goals, stakeholder communication goals, and a hypermedia requirement taxonomy to facilitate web conceptual design, and paving the way for a systematic usability evaluation. AWARE comprises a conceptual toolkit and a notation for effective requirements documentation. AWARE concepts and notation represent a useful communication and analysis conceptual tool that may support in the elicitation, negotiation, analysis and validation of requirements from the relevant stakeholders (users included). The empirical validation of the model is carried out in two ways. Firstly, the model has been employed in web projects on the field. These case studies and the lessons learnt will be presented and discussed to assess advantages and limits of the proposal. Secondly, a sample of web analysts and designers has been asked to study and apply the model: the feedback gathered is positive and encouraging for further improvement.Lo sviluppo di applicazioni web necessita di strumenti efficaci per gestire alcuni aspetti essenziali del processo di analisi dei requisiti: l'identificazione di obiettivi di comunicazione strategici, la presenza di una varietà di profili utente e di stakeholders, le definizione di requisiti ipermediali (riguardanti navigazione, interazione, contenuto e presentazione), e il riuso dei requisiti per una pianificazione efficace della valutazione dell'usabilità. Sono necessarie tecniche usabili sia dagli stakeholders che dai progettisti, che richiedono un tempo breve per essere appresi ed usati con efficacia, mostrando vantaggi significativi ai gestori di progetti complessi. La tesi definisce AWARE (Analysis of Web Application Requirements) - una metodologia per l'analisi dei requisiti specifica per la gestione di siti web (ed applicazioni interattive) con forti componenti comunicative. La metodologia estende le tecniche esistenti dell''analisi dei requisiti basate su approcci goal-oriented e scenario-based, introducendo una tassonomia di requisiti specifica per siti web (che permette di dare un input strutturato all'attività di progetazione), strumenti per l'identificazione e l'analisi di obiettivi ill-defined (generici o mal-definiti) e di obiettivi comunicativi e supporto metodologico per la valutazione dell'usabilità basata sui requisiti dell'applicazione. La metodologia AWARE è stata valutata sul campo attraverso progetti con professionisti del settore (web designers e IT managers), e grazie ad interventi di formazione in aziende specializzate nella comunicazione su web

An i*-based Reengineering Framework for Requirements Engineering

Avui en dia, els sistemes d'informació són un actiu clau en les organitzacions i sovint els proporcionen un avantatges competitiu. Per a que això segueixi així, han de ser mantinguts i evolucionats d'acord amb els objectius estratègics de la organització. Aquesta evolució inclou els requeriments del sistema d'informació, la tecnologia emprada i els processos suportats. L'impacte dels canvis pot anar des de petites modificacions al desenvolupament d'un nou sistema d'informació i, per aquest motiu, l'evolució dels sistemes d'informació s'analitza durant la fase de requeriments, on es possible avaluar-ne la magnitud utilitzant menys recursos. Des d'aquest punt de vista, els mètodes de l'enginyeria de requeriments i els de la reenginyeria de processos sovint comparteixen els mateixos objectius i es pot considerar que la reenginyeria de processos es adequada tant per al desenvolupament com per al manteniment dels sistemes d'informació. El llenguatge i* està orientat a objectius i permet modelar els sistemes d'informació en termes d'actors i dependencies entre ells. El llenguatge i* s'utilitza en l'enginyeria de requeriments i en la reenginyeria de processos de negoci, però no existeixen gaires propostes comunes a ambdues disciplines. Amb l'objectiu d'utilitzar el llenguatge i* en la reenginyeria de processos, s'ha definit PRiM, un mètode basat en i* per a la reenginyeria de processos (Proces Reenginieering i*-based Method). PRiM assumeix que ja existeix un procés que s'utilitzarà com a punt de partida per l'especificació o l'evolució del nou sistema d'informació. El mètode PRiM consta de sis fases: 1) l'anàlisi dels processos i dels sistemes d'informació actuals, 2) la construcció del model i*, 3) la reenginyeria dels processos actuals, 4) la generació de models i* representant les diferents alternatives, 5) l'avaluació de les alternatives utilitzant mètriques estructurals i 6) l'especificació del nou sistema d'informació a partir del model i* escollit. En les sis fases de PRiM, s'utilitzen diferents mètodes i tècniques algunes creades expressament pel mètode i d'altres provinents de l'enginyeria de requeriments i la reenginyeria de processos. Tot i això, hi ha altres mètodes i tècniques que poden ser utilitzades enlloc d'aquestes i que poden ser mes convenients quan les condicions d'aplicació del mètode canvien. Per tal de permetre la selecció i inclusió d'altres tècniques, es proposa l'aplicació de l'enginyeria de mètodes (Method Engineering). Aquesta disciplina permet construir nous mètodes a partir de parts de mètodes ja existents, i s'ha utilitzat per definir un mètode marc per a la reenginyeria anomenat ReeF (Reengineering Framework). A ReeF, les sis fases de PRiM es presenten de forma genèrica per tal de permetre la selecció de la tècnica més apropiada per cada una de les fases, a partir de l'experiència de l'usuari com dels seus coneixements de l'aplicació. Com a exemple d'aplicació de ReeF, s'ha definit el mètode SARiM.Les contribucions principals de la tesis son dues. En primer lloc, els dos mètodes basats en i* definits (PRiM per a la reenginyeria de processos, i SARiM, per a la reenginyeria d'arquitectures software). En segon lloc, les diferents tècniques i* definides en PRiM i que poden ser utilitzades per construir models i*, generar alternatives i avaluar-les amb mètriques estructurals. Aquestes tècniques i mètodes s'han obtingut a partir de l'estudi de l'estat de l'art i s'han validat en diferents casos d'estudi formatius i en un cas d'estudi industrial. Com a suport, s'han desenvolupat dues eines: 1) REDEPEND-REACT, que permet la modelització gràfica de models i*, la generació d'alternatives i la definició de mètriques estructurals, i 2) J-PRiM, que dóna suport a les fases de PRiM mitjançant el tractament textual dels models i*.Information Systems are a crucial asset of the organizations and can provide competitive advantages to them. However, once the Information System is built, it has to be maintained and evolved, which includes changes on the requirements, the technology used, or the business processes supported. All these changes are diverse in nature and may require different treatments according to their impact, ranging from small improvements to the deployment of a new Information System. In both situations, changes are addressed at the requirements level, where decisions are analysed involving less resources. Because Requirements Engineering and Business Process Reengineering methods share common activities, and the design of the Information System with the business strategy has to be maintained during its evolution, a Business Process Reengineering approach is adequate for addressing Information Systems Development when there is an existing Information System to be used as starting point. The i* framework is a well-consolidated goal-oriented approach that allows to model Information Systems in a graphical way, in terms of actors and dependencies among them. The i* framework addresses Requirements Engineering and Business Process Reengineering but none of the i*-based existing approaches provides a complete framework for reengineering. In order to explore the applicability of i* for a reengineering framework, we have defined PRiM: a Process Reengineering i* Method, which assumes that there is an existing process that is the basis for the specification of the new Information System. PRiM is a six-phase method that combines techniques from the fields of Business Process Reengineering and Requirements Engineering and defines new techniques when needed. As a result PRiM addresses: 1) the analysis of the current process using socio-technical analysis techniques; 2) the construction of the i* model by differentiating the operationalization of the process form the strategic intentionality behind it; 3) the reengineering of the current process based on its analysis for improvements using goal acquisition techniques; 4) the generation of alternatives based on heuristics and patterns; 5) the evaluation of alternatives by defining structural metrics; and, 6) the specification of the new Information System from the selected i* model.There are several techniques from the Requirements Engineering and Business Process Reengineering fields, that can be used instead the ones selected in PRiM. Therefore, in order to not enforce the application of a certain technique we propose a more generic framework where to use and combine them. Method Engineering is the discipline that constructs new methods from parts of existing ones and, so, it is the approach adopted to define ReeF: a Reengineering Framework. In ReeF the six phases of PRiM are abstracted and generalized in order to allow selecting the most appropriate techniques for each of the phases, depending on the user expertise and the domain of application. As an example of the applicability of ReeF, the new method SARiM is defined. The main contributions of this work are twofold. On the one hand, two i*-based methods are defined: the PRiM method, which addresses process reengineering, and SARiM, which addresses software architecture reengineering. On the other hand, we provide several i*-based techniques to be used for constructing i* models, generating alternatives, and evaluating them using Structural Metrics. These methods and techniques are based on exhaustive review of existing work and their validation is done by means of several formative case studies and an industrial case study. Tool support has been developed for the approach: REDEPEND-REACT supporting the graphical modelling of i*, the generation of alternatives and the definition of Structural Metrics; and J-PRiM supporting all the phases of the PRiM method using a textual visualization of the i* models

Reasoning of Competitive Non-Functional Requirements in Agent-Based Models

During the decision-making process in real-time competitive environments, there is a need to perform concurrent optimisation of multiple competitive objectives to select an optimal design decision for interdependent stakeholders. To handle such issues, this thesis successfully assimilates the goal-oriented requirements-engineering knowledge with analytical decision-making approaches to facilitate reasoning and analysis by encouraging stakeholders’ involvement. This leads to optimal decisions with domain knowledge improvement in the agent-based i*-goal model by balancing multiple conflicting non-functional requirements reciprocally

Ontological analysis of means-end links

The i* community has raised several main dialects and dozens of variations in the definition of the i* language. Differences may be found related not just to the representation of new concepts but to the very core of the i* language. In previous work we have tackled this issue mainly from a syntactic point of view, using metamodels and syntactic-based model interoperability frameworks. In this paper, we go one step beyond and consider the use of foundational ontologies in general, and UFO in particular, as a way to clarify the meaning of core i* constructs and as the basis to propose a normative definition. We focus here on one of the most characteristics i* constructs, namely means-end links.Postprint (published version

Integrating requirements prioritization and selection into goal models

Requirements engineering is the first main activity in software development process. It must address the individual goals of the organization. The inadequate, inconsistent, incomplete and ambiguous requirements are main obstacles on the quality of software systems. Goal Oriented Requirements Engineering (GORE) starts with abstracts high level goals. These goals are refined to lower levels until they are assignable to agents. During GORE analysis, decisions need to be made among alternatives at various positions. Decisions involve different stakeholders which may contradict with each other based on certain criteria. In the context of GORE, the support for identifying and managing the criteria for requirements selection process is required. The criteria are based on stakeholders needs and preferences and therefore stakeholders opinions need to be involved in selection process. It helps to identify the importance of requirement according to stakeholders understandings and needs. It also helps in the understanding of interaction between system and stakeholders (stakeholders involvement in making important decisions) and by documenting the stakeholder preferences early in GORE, helps to identify inconsistencies early in the requirements engineering. Software quality requirements are essential part for the success of software development. Defined and guaranteed quality in software development requires identifying, refining, and predicting quality properties by appropriate means. Goal models and quality models are useful for modelling of functional goals as well as for quality goals. This thesis presents the integration of goal models with quality models, which helps to involve stakeholders opinions and the representation of dependencies among goals and quality models. The integration of goal models and quality models helps in the derivation of customized quality models. The integrated goal-quality model representing the functional requirements and quality requirements is used to rank each functional requirement arising from functional goals and quality requirement arising from quality goals. Triangular Fuzzy Numbers (TFN) are used to represent stakeholder opinions for prioritizing requirements. By defuzzification process on TFN, stakeholders opinions are quantified. TFN and defuzzification process is also used to prioritize the identified relationships among functional and non-functional requirements. In the last step development constraints are used to re-prioritize the requirements. After final prioritization, a selection algorithm helps to select the requirements based on benefit over cost ratio. The algorithm makes sure that maximum number of requirements are selected while fulfilling the upper cost limit. Thus the whole process helps in the selection of requirements based on stakeholders opinions, goal-quality models interaction and development constraints. The thesis also presents an integrative model of influence factors to tailor product line development processes according to different project needs, organizational goals, individual goals of the developers or constraints of the environment. Tailoring is realized with prioritized attributes, with which the resulting elements of the product, process and project analysed are ranked. An integrative model for the description of stakeholder needs and goals in relation to the development process artefacts and the development environment specifics is needed, to be able to analyse potential influences of changing goals early in the project development. The proposed tailoring meta-model includes goal models, SPEM models and requirements to development processes. With this model stakeholder specific goals can be used to support binding a variable part of the development process. This support addresses soft factors as well as concrete requirements.Requirements Engineering ist der erste Schritt im Softwareentwicklungsprozess. Er dient zur Aufnahme organisationsabhängiger Ziele und Anforderungen. Unangemessene, inkonsistente, unvollständige oder mehrdeutige Anforderungen können die Qualität von Softwaresystem stark negativ beeinflussen. Goal Oriented Requirements Engineering (GORE) beginnt mit der Entwicklung von übergeordneter Zielen, welche in weiteren Entwicklungsstufen verfeinert werden, bis sie einer verantwortlichen Person zugewiesen werden können. Während einer GORE Analyse werden an verschiedenen Stellen Entscheidungen über Alternativen getroffen. Diese Entscheidungen betreffen unterschiedliche Akteure, die sich in ihren Ansichten widersprechen können. Im Rahmen von GORE wird die Unterstützung zur Identifizierung und Verwaltung von Kriterien zur Auswahl von Anforderungen benötigt. Diese Kriterien basieren auf den Vorstellungen und Vorlieben von Stakeholdern, daher ist eine Integration aller Stakeholder in den Auswahlprozess erforderlich. Dies soll dabei helfen, die Bedeutung bestimmter Anforderungen auf Basis der betroffenen Personen zu identifizieren und aufzuarbeiten. Darüber hinaus hilft GORE bei der Kommunikation zwischen System und Akteuren durch ihren Einbezug in wichtige Entscheidungen. Durch frühzeitige Dokumentation des tatsächlichen Stakholderbedarfs können Inkonsistenzen im Requirements Engineering frühzeitig ermittelt werden. Die Bestimmung von Software Qualitätsmerkmalen ist wesentlicher Erfolgsfaktor in der Software Entwicklung. Zur Gewährleistung einer qualitativen Softwareentwicklung und eines entsprechenden Produktes sind die Identifizierung, die Verfeinerung und die Vorhersage von Qualitätseigenschaften jederzeit durch geeignete Maßnahmen erforderlich. Goal Models und Quality Models sind wertvolle Werkzeuge zur Ermittlung und Modellierung funktionaler und nicht-funktionaler Anforderungen und Ziele. Diese Arbeit enthält einen Lösungsansatz zur Integration von Goal Models und Quality Models, der dazu beitragen soll, Stakeholder und Abhängigkeiten zwischen Goal und Quality Models einzubeziehen und sichtbar zu machen. Die Integration von Goal Models und Quality Models soll zur Ableitung spezifischer Quality Models beitragen. Somit kann das integrierte Goal-Quality Model, welches die funktionalen Anforderungen und die Qualitätsanforderungen vereint, zur Priorisierung aller funktionalen Anforderung, die sich aus den funktionalen Zielen ergeben, und aller Qualitätsanforderungen, die aus Qualitätszielen resultieren, dienen. Zur Priorisierung der Anforderung auf Basis der Stakeholderbedarfe werden Triangular Fuzzy Numbers (TFN) verwendet. Nach der endgültigen Priorisierung dient ein spezieller Algorithmus zur Einschätzung und Auswahl der Anforderungen auf Basis einer Kosten-Nutzen-Analyse. Dieser Algorithmus stellt sicher, dass unter Einhaltung einer von der Organisation gewählten Kostenobergrenze die maximale Anzahl der Anforderungen umgesetzt werden kann. Der gesamte Prozess dient demnach zur Anforderungsanalyse unter Berücksichtigung verschiedener Interessengruppen, Abhängigkeiten, sowie durch den Einbezug von Grenzen, die sich beim Zusammenspiel von Goal-Quality Models und der Softwareentwicklung ergeben können. Darüber hinaus enthält die Arbeit ein integratives Modell, um Entwicklungsprozesse während der Erstellung von Produktlinien an Einflussfaktoren, wie Projektbedürfnisse, Organisationsziele, individuelle Ziele von Entwicklern oder an Umweltbedingungen anzupassen. Dieses sogenannte Tailoring wird durch Priorisierung von Attributen erreicht, welche verschiedene Elemente des zu erzeugende Produktes, des Prozesses oder des Projektes analysieren und nach Bedeutung sortieren. Ein integratives Modell zur Beschreibung von Stakeholderbedürfnissen und -zielen in Bezug auf die Artefakte des Entwicklungsprozesses und die Besonderheiten einer Entwicklungsumgebung wird benötigt, um potenzielle Einflüsse sich verändernder Ziele frühzeitig während der Projektentwicklung zu analysieren. Das hier vorgestellte Tailoring-Meta-Model beinhaltet Goal-Models, SPEM Models und Requirements hinsichtlich Entwicklungsprozesse. Mithilfe dieses Modells können stakeholderspezifische Ziele dazu verwendet werden, um einen variablen Teil eines Entwicklungsprozesses projektbezogen zu gestalten. Auf diese Weise können weiche Faktoren genauso integriert werden, wie konkrete Anforderungen

A Value-Driven Framework for Software Architecture

Software that is not aligned with the business values of the organization for which it was developed does not entirely fulfill its raison d’etre. Business values represent what is important in a company, or organization, and should influence the overall software system behavior, contributing to the overall success of the organization. However, approaches to derive a software architecture considering the business values exchanged between an organization and its market players are lacking. Our quest is to address this problem and investigate how to derive value-centered architectural models systematically. We used the Technology Research method to address this PhD research question. This methodological approach proposes three steps: problem analysis, innovation, and validation. The problem analysis was performed using systematic studies of the literature to obtain full coverage on the main themes of this work, particularly, business value modeling, software architecture methods, and software architecture derivation methods. Next, the innovation step was accomplished by creating a framework for the derivation of a software reference architecture model considering an organization’s business values. The resulting framework is composed of three core modules: Business Value Modeling, Agile Reference Architecture Modeling, and Goal-Driven SOA Architecture Modeling. While the Business value modeling module focuses on building a stakeholder-centric business specification, the Agile Reference Architecture Modeling and the Goal-Driven SOA Architecture Modeling modules concentrate on generating a software reference architecture aligned with the business value specification. Finally, the validation part of our framework is achieved through proof-of-concept prototypes for three new domain specific languages, case studies, and quasi-experiments, including a family of controlled experiments. The findings from our research show that the complexity and lack of rigor in the existing approaches to represent business values can be addressed by an early requirements specification method that represents the value exchanges of a business. Also, by using sophisticated model-driven engineering techniques (e.g., metamodels, model transformations, and model transformation languages), it was possible to obtain source generators to derive a software architecture model based on early requirements value models, while assuring traceability throughout the architectural derivation process. In conclusion, despite using sophisticated techniques, the derivation process of a software reference architecture is helped by simple to use methods supported by black box transformations and guidelines that facilitate the activities for the less experienced software architects. The experimental validation process used confirmed that our framework is feasible and perceived as easy to use and useful, also indicating that the participants of the experiments intend to use it in the future