Requirements traceability is the ability to relate requirements back to stakeholders and forward to corresponding design artifacts, code, and test cases. Although considerable research has been devoted to relating requirements in both forward and backward directions, less attention has been paid to relating requirements with other requirements. Relations between requirements influence a number of activities during software development such as consistency checking and change management. In most approaches and tools, there is a lack of precise definition of requirements relations. In this respect, deficient results may be produced. In this paper, we aim at formal definitions of the relation types in order to enable reasoning about requirements relations. We give a requirements metamodel with commonly used relation types. The semantics of the relations is provided with a formalization in first-order logic. We use the formalization for consistency checking of relations and for inferring new relations. A tool has been built to support both reasoning activities. We illustrate our approach in an example which shows that the formal semantics of relation types enables new relations to be inferred and contradicting relations in requirements documents to be determined.

In requirements engineering, there are several approaches for requirements modeling such as goal-oriented, aspect-driven, and system requirements modeling. In practice, companies often customize a given approach to their specific needs. Thus, we seek a solution that allows customization in a systematic way. In this paper, we propose a metamodel for requirements models (called core metamodel) and an approach for customizing this metamodel in order to support various requirements modeling approaches. The core metamodel represents the common concepts extracted from some prevalent approaches. We define the semantics of the concepts and the relations in the core metamodel. Based on this formalization, we can perform reasoning on requirements that may detect implicit relations and inconsistencies. Our approach for customization keeps the semantics of the core concepts intact and thus allows reuse of tools and reasoning over the customized metamodel. We illustrate the customization of our core metamodel with SysML concepts. As a case study, we apply the reasoning on requirements of an industrial mobile service application based on this customized core requirements metamodel.

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In the period 1986–1991, experiments have been carried out with an introductory course in computer programming, based on functional programming. Due to thorough educational design and evaluation, a successful course has been developed. This has led to a revision of the computer programming education in the first year of the computer science curriculum at the University of Twente.This article describes the approach, the aim of the computer programming course, the outline and subject matter of the course, and the evaluation. Educational research has been done to assess the quality of the course.

Please cite this article in press as: Goknil, A., et al., Generation and validation of traces between requirements and architecture based on formal trace semantics. J. Syst. Software (2013) The size and complexity of software systems make integration of the new/modified requirements to the software system costly and time consuming. The impact of requirements changes on other requirements, design elements and source code should be traced to determine parts of the software to be changed. Considerable research has been devoted to relating requirements and design artifacts with source code. Less attention has been paid to relating requirements (R) with architecture (A) by using well-defined semantics of traces. Traces between R&A might be manually assigned. This is time-consuming, and error prone. Traces might be incomplete and invalid. In this paper, we present an approach for automatic trace generation and validation of traces between requirements (R) and architecture (A). Requirements relations and architecture verification techniques are used. A trace metamodel is defined with commonly used trace types between R&A. We use the semantics of traces and requirements relations for generating and validating traces with a tool support. The tool provides the following: (1) generation and validation of traces by using requirements relations and/or verification of architecture, (2) generation and validation of requirements relations by using traces. The tool is based on model transformation in ATL and termrewriting logic in Maude.

a b s t r a c tContext: Following the evolution of the business needs, the requirements of software systems change continuously and new requirements emerge frequently. Requirements documents are often textual artifacts with structure not explicitly given. When a change in a requirements document is introduced, the requirements engineer may have to manually analyze all the requirements for a single change. This may result in neglecting the actual impact of a change. Consequently, the cost of implementing a change may become several times higher than expected. Objective: In this paper, we aim at improving change impact analysis in requirements by using formal semantics of requirements relations and requirements change types. Method: In our previous work we present a requirements metamodel with commonly used requirements relation types and their semantics formalized in first-order logic. In this paper the classification of requirements changes based on structure of a textual requirement is provided with formal semantics. The formalization of requirements relations and changes is used for propagating proposed changes and consistency checking of proposed changes in requirements models. The tool support for change impact analysis in requirements models is an extension of our Tool for Requirements Inferencing and Consistency Checking (TRIC). Results: The described approach for change impact analysis helps in the elimination of some false positive impacts in change propagation, and enables consistency checking of changes. Conclusion: We illustrate our approach in an example which shows that the formal semantics of requirements relations and change classification enables change alternatives to be proposed semi-automatically, the reduction of some false positive impacts and contradicting changes in requirements to be determined.

In event-driven systems, separating the reactive part of software (i.e., event-driven control) from the non-reactive part is a common design practice. The reactive part is typically structured according to the states and transitions of a system, whereas the non-reactive part is typically structured according to the concepts of the application domain (e.g., the services provided by the system). In such systems, the non-reactive part of software stimulates the reactive part with event calls. Whenever the non-reactive part is modified (e.g., during evolution), the existing event calls may become invalid, new event calls may become necessary, and the two parts of software may become incompatible. Manually finding and repairing these types of defects is a time-consuming and error-prone maintenance task. In this article, we present a solution that combines source code model checking and aspectoriented programming techniques, to reduce the time spent by developers and to automatically find defects, while performing the maintenance task mentioned above. In addition, we present controlled experiments showing that the solution can reduce the time by 75%, and enable the prevention of one defect per 140 lines of source code.

Traceability is considered crucial for establishing and maintaining consistency between software development artifacts. Although considerable research has been devoted to relating requirements and design artifacts with source code, less attention has been paid to relating requirements with architecture by using well-defined semantics of traces. We present a tool that provides trace establishment by using semantics of traces between R&A (Requirements and Architecture). The tool provides the following: (1) generation/validation of traces by using requirements relations and/or verification of architecture, (2) generation/validation of requirements relations by using traces. The tool uses the semantics of traces together with requirements relations and verification results for generating and validating traces. It is based on model transformations in ATL and term-rewriting logic in Maude.