Stephan Bode

Optimisation Process for Maintaining Evolvability during Software Evolution

Software systems have to be changed continuously and evolutionarily throughout the whole time of their development and usage. Meanwhile, the software systems have to remain flexible in order to retain the ability to be extended by additional new features or to be changed. To maintain this ability, known as evolvability, the architecture of such software systems and its evolution must be continuously controlled and, if necessary improved. Existing design methodologies do not provide sufficient support for controlling the evolvability. One reason for this is, that in comparison with software maintainability, evolvability characteristics are hardly defined. This paper discusses evolvability, and introduces a quality model for it. Furthermore, a meta-model-based process for controlling and optimising the evolvability characteristics of software baselines is presented. The feasibility of this approach is shown by a case study based on the results from its implementation in large industrial projects.

Software Architectural Design Meets Security Engineering

Security requirements strongly influence the architectural design of complex IT systems in a similar way as other non-functional requirements. Both security engineering as well as software engineering provide methods to deal with such requirements. However, there is still a critical gap concerning the integration of the methods of these separate fields. In this paper we close this gap with respect to security requirements by proposing a method that combines software engineering approaches with state-of-the-art security engineering principles. This method establishes an explicit alignment between the non-functional goal, the principles in the field of security engineering, and the implementation of a security architecture. The method aims at designing a systems security architecture based on a small, precisely defined, and application-specific trusted computing base. We illustrate this method by means of a case study which describes distributed enterprise resource planning systems using web services to implement business processes across company boundaries.

Towards Comprehensive Modelling by Inter-model Links Using an Integrating Repository

Model-based development techniques enable a high efficiency and the mastering of complexity. For many domains more than one model has to be used to express the relevant information. Many methods use different models without a tight coupling, with a high risk of inconsistencies. Other approaches are based on metamodel extension or unified metamodels, with a limited tool support as consequence. We present an approach for the interconnection between several models in a joint repository by means of dependency relationships. The interconnection is shown between UML models, BPMN models and feature models by examples for variable workflows in mobile systems. The presented approach is implemented by the EMF-based repository EMF Trace, with XML for model representation. Dependencies are determined either automatically by a rule set or manually by explicit references.

Problem-solution mapping for forward and reengineering on architectural level

Software architectures play a key role for the development and evolution of software systems because they have to enable their quality properties such as scalability, flexibility, and security. Software architectural decisions represent a transition from problem space with quality goals and requirements on one side to solution space with technical solutions on the other side. Technical solutions are reusable elements for the work of the architect as for example patterns, styles, frameworks and building blocks. For long-term evolution of the systems, an explicit mapping between goals and solutions is helpful for expressing design knowledge and fundamental decisions. Such a mapping has to bridge between the fields of requirements engineering, software architectural design, and software quality thus enabling reuse. In this paper the Goal Solution Scheme is discussed, which maps quality goals and goal refinements to architectural principles and solutions. The paper extends the approach from the previously discussed forward engineering to re-engineering activities thus covering evolutionary development processes. The evaluation of the approach has been performed in several case studies and projects including a large industrial one.

Usability-Focused Architectural Design for Graphical User Interface Components

Although in recent years some progress in software engineering (SE) and human-computer interaction (HCI) has been made, there is still a gap between the two research areas and their methodologies. Today, from the engineering point of view, the specification and design of graphical user interfaces and their corresponding software architectural components is still a challenging task. The advanced component design methods are not yet integrated with HCI design methodologies to bridge the two fields. This paper presents a methodology, which extends a category-based software architectural design method by integrating HCI approaches. The methodology aims at a better design of graphical user interface (GUI) components in terms of both the architectural quality and usability. The methodology has been successfully evaluated in the development and partial reengineering of an e-commerce system.