Goal-oriented Requirement Language Research Articles

Mission‐based design of UAVs

AbstractOver the past decades, Unmanned Aerial Vehicles (UAVs) have increasingly been used in a wide variety of missions that range from surveillance to delivery. Unlike aircraft that always carry goods and passengers from an airport to another, UAVs do not systematically implement the same type of mission. UAVs are indeed multi‐mission during their time in operation, and the systems engineering approaches developed for one mission aircraft must be adapted to the multi‐mission context. Therefore, UAV design requires application of mission engineering upstream systems engineering, either to assess there is a UAV system that may accomplish a new mission, or to specify a new UAV system according to a given mission. To achieve that goal, the authors of the paper support the use of Model‐Based Mission Engineering. A three‐layer architecture ‐ purpose, operation, functions or capabilities ‐ is proposed as a design framework for missions. The Goal‐Oriented Requirements Language (GRL) serves as mission description language. The paper extends GRL to better address mission‐based design of UAVs. It is proposed to distinguish between internal and external resources. A goal detailing mechanism is introduced. A degraded mode evaluation becomes possible. GRL tools make it possible to evaluate how much a UAV system ‐ at least, an operator, a ground station, and a UAV ‐ may satisfy every stakeholder in both nominal and degraded modes. The proposed approach is applied to a high voltage surveillance UAV. The case study enables the introduction of four actors—Authority, Client, UAV and MissionSupervisor—that turn out to be generic and can be reused for other missions and UAV designs.

An Improved User Requirements Notation (URN) Models’ Construction Approach

Semi-formal software techniques have been very successful in industry, government institutions and other areas such as academia. Arguably, they owe a large part of their success to their graphical notation, which is more human-oriented than their counterpart text-based and formal notation techniques. However, ensuring the consistency between two or more models is one of the known challenges of these techniques. This work looks closely at the specific case of the User Requirements Notation (URN) technique. Although the abstract model of URN provides for link elements to ensure the consistency between its two main components, namely, Goal-Oriented Requirement Language (GRL) and Use Case Maps (UCM), the effective implementation of such links is yet to be fully addressed. This paper performs a detailed analysis of the existing URN models construction process and proposes an improved process with some guidelines to ensure, by construction, the correctness and consistency of the GRL and UCM models. A case study is used throughout the paper to illustrate the suggested solution.

Goal-oriented requirement language model analysis using analytic hierarchy process

We present the application of multi-objective optimisation analytic methodologies to goal models in this research, with the intention of providing various benefits beyond the initial modelling act. Optimisation analysis can be used by modellers to evaluate goal satisfaction, evaluate high-level design alternatives, aid analysts in deciding on high-level requirements and system design, verify the sanity of a model, and improve communication and learning. Goal model analysis may be done in a variety of methods, depending on the nature of the model and the study’s goal. In our work, we use the Goal-Oriented Requirement Language (GRL), which is part of the User Requirements Notation (URN), a new International Telecommunication Union (ITU) recommendation that offers the first standard goal-oriented language. Existing optimisation methods are geared towards maximising objective functions. On the other hand, real-world problems necessitate simultaneous optimisation of both maximising and minimising objective functions. This work explores a GRL model analysis that may accommodate the conflicting goals of various inter-dependent actors in a goal model using the Analytic Hierarchy Process (AHP). By evaluating the qualitative or quantitative satisfaction levels of the actors and intentional elements (e.g., objectives and tasks) that make up the model, we construct a multi-objective optimisation method for analysis using the GRL model. The proposed hybrid technique evaluates the contribution of alternatives to the accomplishment of top softgoals. It is then integrated with the top softgoals’ normalised relative priority values. The integration result may be utilised to assess multiple alternatives based on the requirements problem. Although the URN standard does not mandate a specific propagation algorithm, it does outline certain criteria for developing evaluation mechanisms. Case studies were used to assess the viability of the suggested approach in a simulated environment using JAVA Eclipse and IBM Cplex. The findings revealed that the proposed method can be used to analyse goals in goal models with opposing multi-objective functions.

GRL goal analysis using zero-sum game theory

In Requirements Engineering (RE), goal models are used to represent stakeholder objectives, which are also known as system requirements or system goals. Stakeholder requirements are of two types: functional requirements and non-functional requirements. Goal models are analysed to find out suitable functional requirements amongst ensemble of all functional requirements. RE literature has addressed both qualitative and quantitative methods for performing goal analysis. Recently, operation research techniques have been used for performing optimal goal analysis. The existing optimisation approaches focus on maximising objective functions. But real world problems involve optimisation of both maximising and minimising objective functions simultaneously. In this study, a game theory based approach is used for solving simultaneous optimisation of both maximum and minimum objective functions in goal models. The proposed approach is applied to Goal-Oriented Requirement Language (GRL) framework which is perceived as a standard for goal-modelling. The practicality of the proposed approach was assessed by running the case studies in a simulated environment using JAVA Eclipse combined with IBM Cplex tool. The results showed that the proposed approach aids in the analysis of goals in goal models with opposing objective functions.

Reasoning about Confidence in Goal Satisfaction

Goal models are commonly used requirements engineering artefacts that capture stakeholder requirements and their inter-relationships in a way that supports reasoning about their satisfaction, trade-off analysis, and decision making. However, when there is uncertainty in the data used as evidence to evaluate goal models, it is crucial to understand the confidence or trust level in such evaluations, as uncertainty may increase the risk of making premature or incorrect decisions. Different approaches have been proposed to tackle goal model uncertainty issues and risks. However, none of them considers simple quality measures of collected data as a starting point. In this paper, we propose a Data Quality Tagging and Propagation Mechanism to compute the confidence level of a goal’s satisfaction level based on the quality of input data sources. The paper uses the Goal-oriented Requirement Language (GRL), part of the User Requirements Notation (URN) standard, in examples, with an implementation of the proposed mechanism and a case study conducted in order to demonstrate and assess the approach. The availability of computed confidence levels as an additional piece of information enables decision makers to (i) modulate the satisfaction information returned by goal models and (ii) make better-informed decisions, including looking for higher-quality data when needed.

I*-Based Goal-Oriented Modeling and Requirements Specification of an Urban Railway Interlocking System

Urban railway interlocking system is a safety-critical system, for which interlocking rules are well-defined by international standards to assure safe operations. However, it is very difficult to extract all of the safety requirements in the requirements engineering stage itself and construct a goal model as well. One approach to fulfill this goal is to extract safety requirements from regulations and analyze them at the early stage of the model. Improper specifications regarding the environs of an interlocking system are realized to be accountable for any faults in requirements specifications. Furthermore, nonfunctional requirements are kept aside from requirements specifications. To make an interlocking system operate in an ultra-dependable range we need to address variability issues, so in this paper, we used i*-based goal-oriented requirements language called TGRL to address variability issues as well as blend early and late requirements. The developed model can also be visualized and analyzed using jUCMNav. Finally, the safety requirements to be verified are specified with Formal Tropos, a formal specification language for the i* model.

A Game-theoretic approach to analyze interacting actors in GRL goal models

Goal-oriented requirements engineering aims to capture desired goals and strategies of relevant stakeholders during early requirements engineering stages, using goal models. Goal-oriented modeling techniques support the analysis of system requirements (especially non-functional ones) from an operationalization perspective, through the evaluation of alternative design options. However, conflicts and undesirable interactions between requirements produced from goals are inevitable, especially as stakeholders often aim for different objectives. In this paper, we propose an approach based on game theory and the Goal-oriented Requirement Language (GRL) to reconcile interacting stakeholders (captured as GRL actors), leading to reasonable trade-offs. This approach consists in building a payoff bimatrix that considers all actor’s valid GRL strategies, and computing its Nash equilibrium. Furthermore, we use two optimization techniques to reduce the size of the payoff bimatrix, hence reducing the computational cost of the Nash equilibrium. The approach goes beyond existing work by supporting nonzero-sum games, multiple alternatives, and inter-actor dependencies. We demonstrate the applicability of our game-theoretic modeling and analysis approach using a running example and two GRL models from the literature, with positive results on feasibility and applicability, including performance results.

Modeling and Selecting Frameworks in Terms of Patterns, Tactics and System Qualities

Selecting a framework and documenting the rationale for choosing it is an essential task for system architects. Different framework selection approaches have been proposed in the literature. However, none of these connect frameworks to qualities based on their implemented patterns and tactics. In this paper, we propose a way to semi-automatically compare the quality attributes of frameworks by extracting the patterns and tactics from a framework’s source code and documenting them to connect frameworks to requirements upon which a selection can be made. We use a tool called Archie (a tool used to extract tactics from a Java-based system’s code) to extract the patterns/tactics from the implementation code of frameworks. We then document and model these patterns/tactics and their impact on qualities using the Goal-oriented Requirements Language (GRL). After that, we reuse these models of patterns and tactics to model frameworks in terms of their implemented patterns and tactics. The satisfaction level of the quality requirements integrated with other criteria such as the preferences of an architect provide architects with a tool for comparing different frameworks and documenting their rationale for choosing a framework. As a validation of the approach, we apply it to three realistic case studies with promising results.

RationalGRL: A framework for argumentation and goal modeling

Goal-oriented requirements modeling approaches aim to capture the intentions of the stakeholders involved in the development of an information system as goals and tasks. The process of constructing such goal models usually involves discussions between a requirements engineer and a group of stakeholders. Not all the arguments in such discussions can be captured as goals or tasks: e.g., the discussion whether to accept or reject a certain goal and the rationale for acceptance or rejection cannot be captured in goal models. In this paper, we apply techniques from computational argumentation to a goal modeling approach by using a coding analysis in which stakeholders discuss requirements for a Traffic Simulator. We combine a simplified version of a traditional goal model, the Goal-oriented Requirements Language (GRL), with ideas from argumentation on schemes for practical reasoning into a new framework (RationalGRL). RationalGRL provides a formal semantics and tool support to capture the discussions and outcomes of the argumentation process that leads to a goal model. We also define the RationalGRL development process to create a RationalGRL model.

An automated change impact analysis approach for User Requirements Notation models

Requirements and their models often evolve to reflect changing needs, technologies, and regulations. The decision to implement proposed changes to requirements models relies on means to capture and analyze the potential impact of such changes. The User Requirements Notation (URN) is a standardized requirements modeling language that incorporates two complementary views based on Use Case Maps (UCM), for expressing scenarios and processes bound to architectural components, and on the Goal-oriented Requirement Language (GRL), for capturing the goals of actors and their relationships. This paper presents a new Change Impact Analysis (CIA) approach for URN models. Following a proposed change, this approach helps identify potentially impacted URN constructs within the selected GRL/UCM view, as well as throughout other view elements connected with URN links. This URN-oriented CIA approach is implemented as an extension of the jUCMNav modeling environment, and its applicability is demonstrated using an illustrative URN specification and three real and publicly available specifications. Furthermore, an empirical study involving 10 participants is used to assess the accuracy of this approach in identifying impacted URN elements upon specification changes. Results indicate excellent accuracy and a significant reduction in user-perceived difficulty when estimating the impact of changes in URN specifications.

Expanding the nature and scope of requirements for service systems through Service-Dominant Logic: the case of a telemonitoring service

A renewed understanding of service as a process of resource application and integration, rather than as digital or physical products, shifts the focus of service engineering to the value-creating relationships among entities within complex socio-technical service systems. This understanding is based on Service-Dominant Logic (S-D Logic), a recognized perspective on value creation in modern economies. Goal-oriented modeling, in particular when integrating agent-oriented principles, has been shown to be a suitable method for designing and developing service systems based on S-D Logic principles. Yet, the impact of S-D Logic on the nature and scope of requirements to be elicited and analyzed when designing a service system using goal-oriented modeling has not been clearly articulated. We propose a domain-specific profile of the Goal-oriented Requirement Language, a goal-oriented modeling language part of the User Requirements Notation standard, as well as a set of heuristics for eliciting requirements for service systems. Both are derived from a metamodel of service systems based on S-D Logic principles. Using a case study of a telemonitoring service, we demonstrate that using the heuristics to generate a requirements model for the design of the service results in a more complete set of requirements than existing solutions for telemonitoring services. The results of this study contribute to a better understanding of the impact of S-D Logic on service engineering, pointing toward the need for more research on the impact of operationalized domain theories on requirements engineering.

Measuring Goal-Oriented Requirements Language Actor Stability

Measuring Goal-Oriented Requirements Language Actor Stability

Goal model analysis of autonomy requirements for Unmanned Aircraft Systems

Designing Unmanned Aircraft Systems (UASs) for optimal autonomy while meeting user requirements is quite challenging. Researchers have focused on improving autonomy algorithms and verification methods to ensure safe and reliable autonomous behavior in UASs, but little research has been conducted on requirements engineering for UASs to answer design questions and explore the trade space for using autonomy to satisfy user requirements. This paper introduces a method to determine an optimal set of autonomous capabilities that satisfies UAS user requirements in the early stages of conceptual design. The method uses a modified Autonomy Requirements Engineering (ARE) process that applies quantitative measures and statistical analysis to Goal-Oriented Requirements Engineering (GORE). We demonstrate this method in a case study of a “disaster robot,” i.e., a hazard response UAS for which the autonomy requirements were optimized using a goal model developed in the Goal-oriented Requirement Language (GRL), as implemented in the modeling tool jUCMNav. The high-level goals of the hazard response UAS—system performance, cost, and safety—were evaluated using the formula-based GRL strategy evaluation algorithm resident in jUCMNav version 6.0. An autonomy trade space study was conducted through a Design and Analysis of Simulation Experiments (DASE). Our designed simulation experiment inserted the number of trials (evaluation strategies) and inputs into the goal model, and evaluation data were analyzed to optimize design factors based on user weightings of the response variables. This paper presents a structured method of ARE for UASs, which could be adopted more broadly across other domains, demonstrating how to optimize autonomous capabilities for different design conditions.

Requirements engineering for the design of conceptual modeling languages

Conceptual modeling languages are purposeful artifacts, hence their design should also start from the purpose that they serve. Such purposeful design addresses the requirements engineering concern of a language specification being aligned with the goals of its users. Thereby relevance of the language is ensured, instead of developing a language for language's sake. We posit that this addresses some known issues that are due to a misalignment between a language's specification and the goals of its intended users. In this paper, we introduce vGREL, a goal- and value-oriented approach for purposeful language development. vGREL helps language engineers to start the design of conceptual modeling languages with requirements engineering exercises. To this end vGREL provides (1) a purpose driven requirements engineering process for language design; (2) a value profile for the Goal- oriented Requirements Language (GRL) to enable analysis and reasoning during the process and capture its results; and leverages (3) the software tool support of GRL for decision making during language design. To illustrate vGREL, we apply it to a case study on responsibility-based access rights management. Furthermore, we present reflections on vGREL from the language engineer involved in the case study.

An empirical approach toward the resolution of conflicts in goal-oriented models

One significant problem requirements engineers have to cope with is the management of unclear requirements, ambiguities, and conflicts that may arise between stakeholders. Such issues may be desirable since they may allow for further elicitation of requirements that would have been missed otherwise. Goal models capture the objectives and other intentions of different stakeholders, together with their relationships. They can be used to refine unclear requirements and to detect conflicts and ambiguities early during model validation. However, resolving such ambiguities and conflicts is key for the successful implementation of the goal models. In this paper, we propose a novel approach to validate models in the Goal-oriented Requirement Language and resolve conflicts between the perspectives of intervening stakeholders (and especially between stakeholders of a given group). Our approach is based on a statistical analysis of empirical data that we collect from surveys designed for each group of stakeholders. We apply concept analysis in order to fix goal-model artifacts that are subject to conflict. We illustrate our approach using a case study of a goal model describing the involvement of undergraduate students in university research activities.

A questionnaire-based survey methodology for systematically validating goal-oriented models

Goal models represent interests, intentions, and strategies of different stakeholders. Reasoning about the goals of a system unavoidably involves the transformation of unclear stakeholder requirements into goal-oriented models. The ability to validate goal models would support the early detection of unclear requirements, ambiguities, and conflicts. In this paper, we propose a novel validation approach based on the Goal-oriented Requirement Language (GRL) to check the correctness of GRL goal models through statistical analyses of data collected from generated questionnaires. System stakeholders (e.g., customers, shareholders, and managers) may have different objectives, interests, and priorities. Stakeholder conflicts arise when the needs of some group of stakeholder compromise the expectations of some other group(s) of stakeholders. Our proposed approach allows for early detection of potential conflicts amongst intervening stakeholders of the system. In order to illustrate and demonstrate the feasibility of the approach, we apply it to a case study of a GRL model describing the fostering of the relationship between the university and its alumni. The approach brings unique benefits over the state of the art and is complementary to existing validation approaches.

Data Warehouse Design with Goal-oriented Requirements Language

The data warehouse is an integrated place for data in support of decision-making. Decision makers can improve their complex decision making and problem solving via implementation of a data warehouse. The main metrics of a successful data warehouse is the degree to which it meets its purpose. Unfortunately, a large percentage of data warehouses fail to meet business objectives that designed based on traditional solutions of programming concepts. In this paper we propose a goal-oriented approach to requirement analysis for data warehouses, a software engineering methodology based on agent, which is founded on i* organizational modeling frame work. It covers the whole software development process, used from the early phase of requirements analysis to the fulfillment of the final system. This approach not only allows us for a deeper understanding of the operational environment, but also the interactions between software and human agents.

Evaluating goal models within the goal-oriented requirement language

In this article, we introduce the application of rigorous analysis procedures to goal models to provide several benefits beyond the initial act of modeling. Such analysis can allow modelers to asse...

Evaluating goal models within the goal-oriented requirement language

In this article, we introduce the application of rigorous analysis procedures to goal models to provide several benefits beyond the initial act of modeling. Such analysis can allow modelers to assess the satisfaction of goals, facilitate evaluation of high-level design alternatives, help analysts decide on the high-level requirements and design of the system, test the sanity of a model, and support communication and learning. The analysis of goal models can be done in very different ways depending on the nature of the model and the purpose of the analysis. In our work, we use the Goal-oriented Requirement Language (GRL), which is part of the User Requirements Notation (URN). URN, a new Recommendation of the International Telecommunications Union, provides the first standard goal-oriented language. Using GRL, we develop an approach to analysis that can be done by evaluating qualitative or quantitative satisfaction levels of the actors and intentional elements (e.g., goals and tasks) composing the model. Initial satisfaction levels for some of the intentional elements are provided in a strategy and then propagated to the other intentional elements of the model through the various links that connect them. The results allow for an assessment of the relative effectiveness of design alternatives at the requirements level. Although no specific propagation algorithm is imposed in the URN standard, different criteria for defining evaluation mechanisms are described. We provide three algorithms (quantitative, qualitative, and hybrid) as examples, which satisfy the constraints imposed by the standard. These algorithms have been implemented in the open-source jUCMNav tool, an Eclipse-based editor for URN models. The algorithms are presented and compared with the help of a telecommunication system example. © 2010 Wiley Periodicals, Inc.

An MDE modeling framework for measurable goal-oriented requirements

It is a proved fact that the appropriate management of requirements is one of the most influential factors in the success of software development projects. With the advent of the model-driven engineering (MDE) development paradigm, the need for formal gathering mechanisms, which provide the necessary degree of nonambiguity and detail, has led to the proposal of a myriad of requirements metamodels. However, a great disparity exists, both in the concepts/relationships and in the underlying semantics involved in each metamodel. Moreover, most existing proposals lack backward (e.g., alignment with business goals) or forward (e.g., connection with validation methods) traceability. In view of this situation, this article proposes a “measurable requirements metamodel” that offers support to the elicitation of measurable requirements. This support is based on the explicit connection of goals, requirements, and measures, thus fostering a goal-driven measurable requirements engineering (RE) perspective. Additionally, since it is well known that metamodels only reflect the abstract syntax of the modeling language, the proposed metamodel also includes a notation (concrete syntax) which, for reasons of understandability, is based on the goal-oriented requirements language (GRL) notation. This notation is supported by a unified modeling language (UML) profile that facilitates its adoption by RE analysts in the context of any UML-based software engineering process. To support this proposal, an Eclipse tool has been developed. This tool permits the integration of measurable requirements as a driving force in the context of a given MDE development process. © 2010 Wiley Periodicals, Inc.