Ernst Sikora

Industry needs and research directions in requirements engineering for embedded systems

The industry has a strong demand for sophisticated requirements engineering (RE) methods in order to manage the high complexity of requirements specifications for software-intensive embedded systems and ensure a high requirements quality. RE methods and techniques proposed by research are only slowly adopted by the industry. An important step to improve the adoption of novel RE approaches is to gain a detailed understanding of the needs, expectations, and constraints that RE approaches must satisfy. We have conducted an industrial study to gain an in-depth understanding of practitioners’ needs concerning RE research and method development. The study involved qualitative interviews as well as quantitative data collection by means of questionnaires. We report on the main results of our study related to five aspects of RE approaches: the use of requirements models, the support for high system complexity, quality assurance for requirements, the transition between RE and architecture design, and the interrelation of RE and safety engineering. Based on the results of the study, we draw conclusions for future RE research.

COSMOD-RE: Supporting the Co-Design of Requirements and Architectural Artifacts

The need for co-designing requirements and architecture for innovative software-intensive systems is widely accepted. In this paper, we present the key ideas of our method COSMOD-RE for supporting the co-design of requirements and architectural artifacts. The backbone of COSMOD-RE is a hierarchy of four abstraction layers. At each layer, a requirements viewpoint and an architectural viewpoint are co-developed and aligned using a goal- and scenario-based approach. COSMOD-RE defines three co-design processes and five sub-processes for each co-design process to structure and guide the co-development.

Requirements engineering for embedded systems: an investigation of industry needs

[Context and Motivation] Requirements engineering (RE) research is expected to provide methods that address the specific challenges of industrial systems engineering. [Question/problem] For this purpose, researchers need a detailed understanding of the needs and expectations that the industry has regarding RE methods. [Principal ideas/results] To identify the key industry needs, we have conducted an in-depth study with representatives from large, internationally operating companies in the domain of embedded systems in Germany. [Contribution] This paper reports on the identified industry needs related to the topics natural language vs. requirements models, support for high system complexity, quality assurance of requirements, and intertwining of RE and design.

Structuring the co-design of requirements and architecture

The need to co-develop requirements and architectural artefacts, especially for innovative solutions, is widely recognised and accepted. Surprisingly, no comprehensive approach exists to structure the co-design process and to support the stakeholders, requirements engineers, and system architects in co-developing innovative requirements and architectural artefacts. In this paper, we propose a method for the co-design of requirements and architectural artefacts based on two viewpoints, the system usage viewpoint and the system architecture viewpoint. Initially, the two viewpoints are nearly decoupled. The method consists of five sub-processes that support the development of each viewpoint, the comparison of the two viewpoints, the consolidation of the viewpoints, and the definition of detailed system requirements based on the two viewpoints. The consolidation of system usage and coarse-grained system architecture is driven by the refinement of system interaction scenarios into architectural scenarios and the refinement of the associated usage goals. Preliminary results of applying our method in industry are reported.

The Co-Development of System Requirements and Functional Architecture

It is widely recognized that in system development, innovative requirements and innovative architectural solutions need to be co-developed. Yet, no comprehensive method exists to support the co-development of requirements and architecture. This chapter describes the COSMOD-RE method for supporting the co-development of requirements and architectural artefacts at four distinct levels of abstraction. An overview on the method is provided, and the activities for supporting the development of system requirements and the functional system architecture are described.

Documenting Application-Specific Adaptations in Software Product Line Engineering

Software product line engineering distinguishes between two types of development processes: domain engineering and application engineering. In domain engineering software artefacts are developed for reuse. In application engineering domain artefacts are reused to create specific applications. Application engineers often face the problem that individual customer needs cannot be satisfied completely by reusing domain artefacts and thus application-specific adaptations are required. Either the domain artefacts or the application artefacts need to be modified to incorporate the application-specific adaptations. We consider the case that individual customer needs are realised by adapting the application artefacts and propose a technique for maintaining traceability between the adapted application artefacts and the domain artefacts. The traceable documentation of application-specific adaptations is facilitated by an application variability model (AVM) which records the differences between the domain artefacts and the application artefacts of a particular application. The approach is formalised using graph transformations.

Supporting the Consistent Specification of Scenarios across Multiple Abstraction Levels

[Context and motivation] In scenario-based requirements engineering for complex software-intensive systems, scenarios must be specified and kept consistent across several levels of abstraction such as system and component level. [Question/problem] Existing scenario-based approaches do not provide a systematic support for the transitions between different abstraction levels such as defining component scenarios based on the system scenarios and the system architecture or checking whether the component scenarios are consistent with the system scenarios. [Principal ideas/results] This paper presents a systematic approach for developing scenarios at multiple abstraction levels supported by automated consistency checks of scenarios across these abstraction levels. [Contribution] We have implemented the consistency check in a tool prototype and evaluated our approach by applying it to a (simplified) adaptive cruise control (ACC) system.

Requirements engineering in complex domains

Complexity in the application domains of software-intensive systems is continuously growing due to at least two reasons. Firstly, technical complexity grows as hardware and software have to interact in individual or even communicating embedded systems. Secondly, social complexity grows as the process organizations of the 1990s are gradually being replaced by loosely coupled networks of actors, often organized around community platforms. In this chapter, we discuss recent solution attempts for these two issues individually, and end with speculating about their possible future interaction.

A Requirements Reference Model for Model-Based Requirements Engineering in the Automotive Domain

[Context and motivation] The use of conceptual models in automotive requirements engineering is impaired due to the lack of appropriate modelling guidelines. [Question/problem] The goal of this paper is to propose a requirements reference model that serves as the basis for defining such guidelines. [Principal ideas/results] The reference model distinguishes three abstraction layers and three content categories for requirements models. [Contribution] The reference model has been successfully applied in the REMsES project to support the development of a model-based requirements engineering approach for the automotive domain.