Predicting Quality Attributes in Component-based Software Systems
Magnus Larsson · Diva portal (Dalarna University Library) · 2004
This is a book about CBSE Component-Based Software Engineering. CBSE is the emerging discipline of the development of software components and the development of systems incorporating such components. Component-based systems are built by assembling components developed independently of the systems. To assemble components, a proprietary code, which connects the components, is usually needed. This code is often referred to as code. In an ideal world of components, the assembly process is smooth and simple: the effort required to obtain the glue code is practically negligible; a system incorporating components knows everything about them their operational interfaces and their non-functional properties and the components are exactly what the system needs; in short, components can be assembled as easily as Lego blocks. In the real world, the component-based development process is complex and often difficult; systems are built from pre-existing components when appropriate and possible and by developing a new code specific to the particular system. The system may know about the syntax of the operational interfaces of the components, but not necessarily their other properties. Developing the glue code can be costly it may take a longer time to develop it than the components concerned. Software components are in fact much harder to assemble than Lego blocks. “Constructing software systems from components is more like having a bathtub full of Tinkertoy, Lego, Erector set, Lincoln logs, Block City, and six other incompatible kits picking out parts that fit specific functions and expecting them to fit together (Mary Shaw: Architectural Issues in Software Reuse: It's Not Just the Functionality, It's the Packaging, Presentation at the Symposium on Software Reusability SSR'99). CBSE tries to make the real world as close as possible to the ideal world of component-based development. There is a long way to go to achieve this goal. In spite of many difficulties, the component-based approach has achieved remarkable success in many domains. A majority of the software programs we use everyday take advantage of component-based technologies. There are however many classes of software in which the utilization of the component-based approach is rudimentary. For these classes of software the specification of how is at least as important as the specification of what. Example of these classes of systems are reliable systems, safety-, businessor missioncritical systems, (also known as dependable systems), embedded systems. The general-purpose component technologies currently available cannot cope with the non-functional (or more correctly extra-functional) requirements of such systems. These additional requirements call for new technologies, new methods and a specific approach of component-based software engineering. This book describes the basic principles, trends in research and practice of CBSE with emphasizes on dependable systems.