This paper reviews the current state of the art of requirements engineering (RE) research and identifies RE research challenges for future systems. First, the paper overviews the highlights of RE research over the past two decades; the research is considered with respect to requirements technologie, including notations and methodologies, developed to address specific RE tasks, such as elicitation, modeling, and analysis. Such a review enables us to identify mature areas of research, as well as areas that warrant further investigation. Next, we identify several research challenges posed by emerging systems for the future. In order to help delineate the scope of future RE research directions, we then identify several strategies for performing RE research. (The spectrum of research strategies ranges from empirical research to paradigm shifts.) Finally, within the context of these RE research strategies, we identify "hot areas" of research that address RE needs for emerging systems of the future.

Over more than two decades, numerous variability modeling techniques have been introduced in academia and industry. However, little is known about the actual use of these techniques. While dozens of experience reports on software product line engineering exist, only very few focus on variability modeling. This lack of empirical data threatens the validity of existing techniques, and hinders their improvement. As part of our effort to improve empirical understanding of variability modeling, we present the results of a survey questionnaire distributed to industrial practitioners. These results provide insights into application scenarios and perceived benefits of variability modeling, the notations and tools used, the scale of industrial models, and experienced challenges and mitigation strategies

Changes to a software system during implementation and maintenance can cause the architecture of a system to deviate from its documented architecture. If design documents are to be useful , maintenance programmers must be able to easily evaluate how closely the documents conform to the code they are meant to describe. Software architecture recovery, which deals with the extraction and analysis of a system's architecture, has gained more tool support in the past few years. However, there is little research on developing effective and efficient architectural conformance methods. In particular, given the increasing emphasis on patterns and styles in the software engineering community, a method needs to explicitly aid a user in identifying architectural patterns. This paper presents a semi-automatic method, called ARM (Architecture Reconstruction Method), that guides a user in the reconstruction of software architectures based on the recognition of patterns. Once the system's actual architecture has been reconstructed, we can analyze conformance of the software to the documented design patterns.

In this paper, we demonstrate how model checking can be used to verify safety properties for eventdriven systems.We present a technique for transforming event-oriented system requirements into statebased structures, which we can then analyze using a state-based model checker. This technique was effective in uncovering violations of system invariants in both an automobile cruise control system and a water-level monitoring system.

One of the accepted techniques for developing and maintaining feature-rich applications is to treat each feature as a separate concem. However, most features are not separate concerns because they override and extend the same basic service. That is, "independent" features are coupled to one another through the system's basic service. As a result, seemingly unrelated features subtly interfere with each other when trying to override the system behaviour in different directions. The problem is how to coordinate features' access to the serviee's shared variables.This paper proposes coordinating features via feature composition. We model each feature as a separate labelled-transition system and define a conflict-free (CF) composition operator that prevents enabled transitions from synchronizing if they interact: if several features' transitions are simultaneously enabled but have conflicting actions, a non-conflicting subset of the enabled transitions are synchronized in the composition. We also define a conflictand violation-free ( CVF) composition operator that prevents enabled transitions from executing if they violate features' invariants. Both composition operators use priorities among features to decide whether to synchronize transitions.