Abstract i* models have been used for requirements specification in many domains, such as healthcare, telecommunication, and air traffic control. Managing the scalability and the complexity of such models is an important challenge in Requirements Engineering (RE). Scalability is also one of the most intractable issues in the design of visual notations in general: a well-known problem with visual representations is that they do not scale well. This issue has led us to investigate scalability in i* models and its variants by means of a systematic mapping study. This paper is an extended version of a previous paper on the scalability of i* including papers indicated by specialists. Moreover, we also discuss the challenges and open issues regarding scalability of i* models and its variants. A total of 126 papers were analyzed in order to understand: how the RE community perceives scalability; and which proposals have considered this topic. We found that scalability issues are indeed perceived as relevant and that further work is still required, even though many potential solutions have already been proposed. This study can be a starting point for researchers aiming to further advance the treatment of scalability in i* models.

O volume do fluido crevicular e diretamente proporcional ao grau de inflamacao dos tecidos periodontais. O sistema PeriopaperR/PeriotronR e amplamente aceito frente a sua capacidade de permitir a mensuracao deste volume. Metodos alternativos para medicao do volume do fluido, no entanto, tem sido propostos. O presente estudo investigou um instrumento alternativo (lupa e regua milimetrada) para medicao do volume e comparou-o com a leitura obtida no Periopaper/Periotrom R (R1) e tiras de papel absorvente (previamente validadas e nas mesmas medidas do PeriopaperR) /PeriotromR (R2). Para tanto, volumes, previamente conhecidos, de saliva foram medidos em Unidades Periotrom (UP) para R1 e R2 e em milimetros: T1: PeriopaperR e T2: papel absorvente. Todas as leituras foram realizadas por examinador treinado e cego para os volumes dispensados. As medidas, para cada volume, foram repetidas tres vezes e, na sequencia, foram geradas as medias. Estes valores foram, entao, comparados (Student’s t test). Nenhuma diferenca entre as medias foi observada tanto para as medidas em UP (R1=66,8 e R2=72,5) quanto em milimetros (T1=2,83 e T2=2,96). O grau de correlacao entre os grupos foi avaliado usando o coeficiente Pearson’s, atingindo-se um valor intragrupo de r=0,98 (R1xT1; R2xT2; R1xT2). Coeficientes de regressao linear foram, tambem, calculados, atingindo-se valores de 23,5 (R1xT1); 26,5 (R2xT2) e 23,3 (R1xT2). A reprodutibilidade do metodo foi aferida, atingindose coeficientes de correlacao intra-classe acima de 0,96. Pode-se concluir que e possivel aferir volume por meio de medicao em milimetros, com alto grau de reprodutibilidade, in vitro. Este metodo podera reduzir custos de investigacoes periodontais.

The volume of crevicular fluid is directly proportional to the degree of periodontal inflammation. The PeriopaperR system, with readings taken using the PeriotronR, has gained wide acceptance in the literature for measuring this volume. Alternative methods have also been proposed. This study investigated an alternative device for measuring the volume and compared it to the readings taken in PeriotronR Units (PU). Strips of absorbent paper (PS) of the same size as Periopapers R (P) were obtained. Next, previously defined volumes were quantified in PU (R1: P and R2: PS) and also in millimeters (T1: P; T2: PS) using an alternative reading method (ruler and magnifying glass). The mean measurements for each volume were compared (Student’s t test) and no difference was detected between them in PU (R1=66.8 and R2=72.5) or in millimeters (T1=2.83 and T2=2.96). The degree of correlation between groups was evaluated using Pearson’s coefficient, with an intragroup r of 0.98 (R1xT1; R2xT2; R1xT2). Linear regression coefficients were also calculated, finding R1xT1=23.5; R2xT2=26.5 and R1xT2=23.3. The method’s reproducibility was verified using intraclass correlation coefficients, with excellent results - all above 0.96. This being so, it was concluded that it is possible to measure the volume collected in millimeters, with a high degree of reproducibility.

Requirements Engineering has been considered a key activity in any Software Engineering process. It is well known that a requirements specification should include not only software specifications but also business models and other kinds of information describing the context in which the intended system will function. In recent years we have observed a growing influence of the object-orientation paradigm. Unfortunately, the current dominant object oriented modeling technique, i.e. Unified Modeling Technique, is ill equipped for modeling early requirements which are typically informal and often focus on Organizational objectives. UML is more suitable for later phases of requirements capture, which usually focus on completeness, consistency, and automated verification of functional requirements for the new system. In this paper, we present some guidelines for the integration of early and late requirements specifications. For the organizational modeling we use the i* framework, which focuses on the description of organizational relationships among various organizational actors, as well as an understanding of the rationale for the alternatives chosen. For the functional requirements specification, we rely on a precise subset of the Unified Modeling Language annotated with constraints described in the Object Constraint Language. A small example is used to illustrate how the requirements process iterates between the early and late requirements specification.