Raian Ali

A goal-based framework for contextual requirements modeling and analysis

Requirements engineering (RE) research often ignores or presumes a uniform nature of the context in which the system operates. This assumption is no longer valid in emerging computing paradigms, such as ambient, pervasive and ubiquitous computing, where it is essential to monitor and adapt to an inherently varying context. Besides influencing the software, context may influence stakeholders’ goals and their choices to meet them. In this paper, we propose a goal-oriented RE modeling and reasoning framework for systems operating in varying contexts. We introduce contextual goal models to relate goals and contexts; context analysis to refine contexts and identify ways to verify them; reasoning techniques to derive requirements reflecting the context and users priorities at runtime; and finally, design time reasoning techniques to derive requirements for a system to be developed at minimum cost and valid in all considered contexts. We illustrate and evaluate our approach through a case study about a museum-guide mobile information system.

The four pillars of crowdsourcing: A reference model

Crowdsourcing is an emerging business model where tasks are accomplished by the general public; the crowd. Crowdsourcing has been used in a variety of disciplines, including information systems development, marketing and operationalization. It has been shown to be a successful model in recommendation systems, multimedia design and evaluation, database design, and search engine evaluation. Despite the increasing academic and industrial interest in crowdsourcing, there is still a high degree of diversity in the interpretation and the application of the concept. This paper analyses the literature and deduces a taxonomy of crowdsourcing. The taxonomy is meant to represent the different configurations of crowdsourcing in its main four pillars: the crowdsourcer, the crowd, the crowdsourced task and the crowdsourcing platform. Our outcome will help researchers and developers as a reference model to concretely and precisely state their particular interpretation and configuration of crowdsourcing.

Requirements-driven adaptive security: Protecting variable assets at runtime

Security is primarily concerned with protecting assets from harm. Identifying and evaluating assets are therefore key activities in any security engineering process - from modeling threats and attacks, discovering existing vulnerabilities, to selecting appropriate countermeasures. However, despite their crucial role, assets are often neglected during the development of secure software systems. Indeed, many systems are designed with fixed security boundaries and assumptions, without the possibility to adapt when assets change unexpectedly, new threats arise, or undiscovered vulnerabilities are revealed. To handle such changes, systems must be capable of dynamically enabling different security countermeasures. This paper promotes assets as first-class entities in engineering secure software systems. An asset model is related to requirements, expressed through a goal model, and the objectives of an attacker, expressed through a threat model. These models are then used as input to build a causal network to analyze system security in different situations, and to enable, when necessary, a set of countermeasures to mitigate security threats. The causal network is conceived as a runtime entity that tracks relevant changes that may arise at runtime, and enables a new set of countermeasures. We illustrate and evaluate our proposed approach by applying it to a substantive example concerned with security of mobile phones.

Reasoning with contextual requirements: Detecting inconsistency and conflicts

Context: The environment in which the system operates, its context, is variable. The autonomous ability of a software to adapt to context has to be planned since the requirements analysis stage as a strong mutual influence between requirements and context does exist. On the one hand, context is a main factor to decide whether to activate a requirement, the applicable alternatives to meet an activated requirement as well as their qualities. On the other hand, the system actions to reach requirements could cause changes in the context. Objectives: Modelling the relationship between requirements and context is a complex task and developing error-free models is hard to achieve without an automated support. The main objective of this paper is to develop a set of automated analysis mechanisms to support the requirements engineers to detect and analyze modelling errors in contextual requirements models. Method: We study the analysis of the contextual goal model which is a requirements model that weaves together the variability of both context and requirements. Goal models are used during the early stages of software development and, thus, our analysis detects errors early in the development process. We develop two analysis mechanisms to detect two kinds of modelling errors. The first mechanism concerns the detection of inconsistent specification of contexts in a goal model. The second concerns the detection of conflicting context changes that arise as a consequence of the actions performed by the system to meet different requirements simultaneously. We support our analysis with a CASE tool and provide a systematic process that guides the construction and analysis of contextual goal models. We illustrate and evaluate our framework via a case study on a smart-home system for supporting the life of people having dementia problems. Results: The evaluation showed a significant ability of our analysis mechanisms to detect errors which were not notable by requirements engineers. Moreover, the evaluation showed acceptable performance of these mechanisms when processing up to medium-sized contextual goal models. The modelling constructs which we proposed as an input to enable the analysis were found easy to understand and capture. Conclusions: Our developed analysis for the detection of inconsistency and conflicts in contextual goal models is an essential step for the entire system correctness. It avoids us developing unusable and unwanted functionalities and functionalities which lead to conflicts when they operate together. Further research to improve our analysis to scale with large-sized models and to consider other kinds of errors is still needed.

A Goal Modeling Framework for Self-contextualizable Software

Self-contextualizability refers to the system ability to autonomously adapt its behaviour to context in order to maintain its objectives satisfied. In this paper, we propose a modeling framework to deal with self-contextualizability at the requirements level. We use Tropos goal models to express requirements; we provide constructs to analyse and represent context at each variation point of the goal model; and we exploit the goal and context analysis to define how the system satisfies its requirements in different contexts. Tropos goal analysis provides constructs to hierarchically analyse goals and discover alternative sets of tasks the system can execute to satisfy goals; our framework extends Tropos goal model by considering context at its variation points, and provides constructs to hierarchically analyse context and discover alternative sets of facts the system has to monitor to verify a context. A self-contextualizable promotion information system scenario is used to illustrate our approach.

Location-Based Software Modeling and Analysis: Tropos-Based Approach

The continuous growth of interest in mobile applications makes the concept of location essential to design and develop software systems. Location-based software is supposed to be able to monitor the surrounding location and choose accordingly the most appropriate behavior. In this paper, we propose a novel conceptual framework to model and analyze location-based software. We mainly focus on the social facets of location adopting concepts such as actor, resource, and location-based behavior. Our approach is based on Tropos methodology and allows the analyst to elicit and model software requirements according to the different locations where the software will operate. We propose an extension of Tropos modeling and adapt its process to suit well with the development of location-based software. The proposed framework also includes automated analysis techniques to reason about the relation between location and location-based software.

Crowdsourcing: A Taxonomy and Systematic Mapping Study

Abstract Context: Crowdsourcing, or tapping into the power of the crowd for problem solving, has gained ever-increasing attraction since it was first introduced. Crowdsourcing has been used in different disciplines, and it is becoming well-accepted in the marketplace as a new business model which utilizes Human Intelligence Tasks (HITs). Objective: While both academia and industry have extensively delved into different aspects of crowdsourcing, there seems to be no common understanding of what crowdsourcing really means and what core and optional features it has. Also, we still lack information on the kinds and disciplines of studies conducted on crowdsourcing and how they defined it in the context of their application area. This paper will clarify this ambiguity by analysing the distribution and demographics of research in crowdsourcing and extracting taxonomy of the variability and commonality in the constructs defining the concept in the literature. Method: We conduct a systematic mapping study and analyse 113 papers, selected via a formal process, and report and discuss the results. The study is combined by a content analysis process to extract a taxonomy of features describing crowdsourcing. Results: We extract and describe the taxonomy of features which characterize crowdsourcing in its four constituents; the crowd, the crowdsourcer, the crowdsourced task and the crowdsourcing platform. In addition, we report on different mappings between these features and the characteristics of the studied papers. We also analyse the distribution of the research using multiple criteria and draw conclusions. For example, our results show a constantly increasing interest in the area, especially in North America and a significant interest from industry. Also, we illustrate that although crowdsourcing is shown to be useful in a variety of disciplines, the research in the field of computer science still seems to be dominant in investigating it. Conclusions: This study allows forming a clear picture of the research in crowdsourcing and understanding the different features of crowdsourcing and their popularity, what type of research was conducted, where and how and by whom. The study enables researchers and practitioners to estimate the current status of the research in this new field. Our taxonomy of extracted features provides a reference model which could be used to configure crowdsourcing and also define it precisely and make design decisions on which of its variation to adopt.

Business processes contextualisation via context analysis

Context-awareness has emerged as a new perspective for business process modelling. Even though some works have studied it, many challenges have not been addressed yet. There is a clear need for approaches that (i) facilitate the identification of the context properties that influence a business process and (ii) provide guidance for correct modelling of contextualised business processes. This paper addresses this need by defining an approach for business process contextualisation via context analysis, a technique that supports reasoning about context and discovery of its relevant properties. The approach facilitates adequate specification of context variants and of business process execution for them. As a result, we obtain business processes that fit their context and are correct.

Towards a Code of Ethics for Gamification at Enterprise

Gamification is an emerging technique which utilises the “fun theory” mainly to motivate people to change their perception and attitude towards certain subjects. Within enterprises, gamification is used to motivate employees to do their tasks more efficiently and perhaps more enjoyably and sometimes to increase their feeling of being members of the enterprise as a community. While the literature has often emphasised the positive side of gamification, mainly from economic and business perspectives, little emphasis has been paid to the ethical use of gamification within enterprises. In this paper we report an empirical research to explore the ethical aspects of using gamification. We follow a mixed methods approach involving participants who are gamification experts, employees and managers. Our findings show that, for gamification, there is a fine line between being a positive tool to motivate employees and being a source of tension and pressure which could then affect the social and mental well-being within the workplace. This paper will evaluate that dual effect and clarify that fine line.

Location-Based Variability for Mobile Information Systems

Advances in size, power, and ubiquity of computing, sensors, and communication technology make possible the development of mobile or nomadic information systems. Variability of location and system behavior is a central issue in mobile information systems, where software behavior has to change and re-adapt to the different location settings. In this paper, we motivate the need for integration of variable location and variable software behavior. We adapt the goal-oriented framework i*/Tropos to model and analyze the alternative goal satisfaction strategies and the location where each alternative can be adopted. We introduce analysis techniques for the proposed location-based models.