In the last decade, a large number of different software component models have been developed, with different aims and using different principles and technologies. This has resulted in a number of models which have many similarities, but also principal differences, and in many cases unclear concepts. Component-based development has not succeeded in providing standard principles, as has, for example, object-oriented development. In order to increase the understanding of the concepts and to differentiate component models more easily, this paper identifies, discusses, and characterizes fundamental principles of component models and provides a Component Model Classification Framework based on these principles. Further, the paper classifies a large number of component models using this framework.

The Unified Modeling Language has attracted many organizations and practitioners. UML is now the de facto modeling language for software development. Several features account for its popularity: it's a standardized notation, rich in expressivity; UML 2.0 provides 13 diagram types that enable modeling several different views and abstraction levels. Furthermore, UML supports domain-specific extensions using stereotypes and tagged values. Finally, several case tools integrate UML modeling with other tasks such as generating code and reverse-engineering models from code. Our study focused on UML use and model quality in actual projects rather than on its adequacy as a notation or language.

The process of component- and component-based system development differs in many significant ways from the "classical" development process of software systems. The main difference is in the separation of the development process of components from the development process of systems. This fact has a significant impact on the development process. Since the component-based approach is a relatively young approach in software engineering, the main emphasis in the area has been in development of technologies, while process modeling is still an unexplored area. This paper analyses the basic characteristics of the component-based approach and its impact on the development process and lifecycle models. The generic lifecycle of component-based systems and the lifecycle of components are discussed, and the different types of development processes are discussed in detail: architecture-driven component development, productline development and COTS-based development. Finally a short case study illustrates the principles and specifics of component-based processes.