Goal-conflict detection based on temporal satisfiability checking

Goal-oriented requirements engineering approaches propose capturing how a system should behave through the speci ca- tion of high-level goals, from which requirements can then be systematically derived. Goals may however admit subtle situations that make them diverge, i.e., not be satis able as a whole under speci c circumstances feasible within the domain, called boundary conditions . While previous work al- lows one to identify boundary conditions for con icting goals written in LTL, it does so through a pattern-based approach, that supports a limited set of patterns, and only produces pre-determined formulations of boundary conditions. We present a novel automated approach to compute bound- ary conditions for general classes of con icting goals expressed in LTL, using a tableaux-based LTL satis ability procedure. A tableau for an LTL formula is a nite representation of all its satisfying models, which we process to produce boundary conditions that violate the formula, indicating divergence situations. We show that our technique can automatically produce boundary conditions that are more general than those obtainable through existing previous pattern-based approaches, and can also generate boundary conditions for goals that are not captured by these patterns

Facilitating connectivity in composite information systems

"To appear in Data Base."Includes bibliographical references.Supported in part by the Dept. of Transportation's Transportation Systems Center. Supported in part by the U.S. Air Force. Supported in part by the Center for Management of Information at the University of Arizona. Supported in part by Citibank.Y. Richard Wang, Stuart E. Madnick

Requirements elicitation through viewpoint control in a natural language environment

While requirements engineering is about building a conceptual model of part of reality, requirements validation involves assessing the model for correctness, completeness, and consistency. Viewpoint resolution is the process of comparing different views of a given situation and reconciling different opinions. In his doctoral dissertation Leite [72] proposes viewpoint resolution as a means for early validation of requirements of large systems. Leite concentrates on the representation of two different views using a special language, and the identification of their syntactic differences. His method relies heavily on redundancy: two viewpoints (systems analysts) should consider the same topic, use the same vocabulary, and use the same rule-based language which constrains how the rules should be expressed. The quality of discrepancies that can be detected using his method depends on the quality of the viewpoints. The hypothesis of this thesis is that, independently of the quality of the viewpoints, the number of viewpoints, the language, and the domain, it is possible to detect better quality discrepancies and to point out problems earlier than Leite's method allows. In the first part of this study, viewpoint-oriented requirements engineering methods are classified into categories based on the kind of multiplicity the methods address: multiple human agents, multiple specification processes, or multiple representation schemes. The classification provides a framework for the comparison and the evaluation of viewpoint-based methods. The study then focuses on the critical evaluation of Leite's method both analytically and experimentally. Counter examples were designed to identify the situations the method cannot handle. The second part of the work concentrates on the development of a method for the very early validation of requirements that improves on Leite's method and pushes the boundaries of the validation process upstream towards fact-finding, and downstream towards conflicts resolution. The Viewpoint Control Method draws its principles from the fields of uncertainty management and natural language engineering. The basic principle of the method is that, in order to make sense of a domain one must learn about the information sources and create models of their behaviour. These models are used to assess pieces of information, in natural language, received from the sources and to resolve conflicts between them. The models are then reassessed in the light of feedback from the results of the process of information evaluation and conflict resolution. Among the implications of this approach is the very early detection of problems, and the treatment of conflict resolution as an explicit and an integral part of the requirements engineering process. The method is designed to operate within a large environment called LOLITA that supports relevant aspects of natural language engineering. In the third part of the study the Viewpoint Control Method is applied and experimentally evaluated, using examples and practical case studies. Comparing the proposed approach to Leite's shows that the Viewpoint Control Method is of wider scope, is able to detect problems earlier, and is able to point out better quality problems. The conclusions of the investigation support the view that underlines the naivety of assuming competence or objectivity of each source of information

Automated Model Synchronization: A Case Study on UML with Maude

Design specifications of software-intensive systems involve models that have been defined with different modelling languages for different purposes. Hence, a specification can be seen as the description of a system from multiple viewpoints, each providing domain-specific constructs for modelling the system in a more precise way. Such heterogeneity of models can jeopardize the consistency of the specification, because updates in one viewpoint may cause unpredictable design errors in other viewpoints, which can then be transferred to the implementation. OMG’s Meta-Object Facility enhances the automation of the model consistency management by providing a uniform format for different modelling languages. In this paper, we illustrate a technique, based on rewriting logic and on strategies for finding inconsistencies in MOF-based heterogeneous specifications and for resolving them in an automated way

On the interplay between consistency, completeness, and correctness in requirements evolution

The initial expression of requirements for a computer-based system is often informal and possibly vague. Requirements engineers need to examine this often incomplete and inconsistent brief expression of needs. Based on the available knowledge and expertise, assumptions are made and conclusions are deduced to transform this 'rough sketch' into more complete, consistent, and hence correct requirements. This paper addresses the question of how to characterize these properties in an evolutionary framework, and what relationships link these properties to a customer's view of correctness. Moreover, we describe in rigorous terms the different kinds of validation checks that must be performed on different parts of a requirements specification in order to ensure that errors (i.e. cases of inconsistency and incompleteness) are detected and marked as such, leading to better quality requirements. © 2003 Elsevier B.V. All rights reserved