Component-based software development - a practitioner's view

Software components are a useful abstraction to manage software systems during their whole lifecycle from early analysis to maintenance. Components can be combined in order to build more complex components or "composed software systems". However, components do not exist independently of component platforms which provide them with a runtime environment. Therefore, developing components means developing components in the context of a dedicated component platform and in many cases in the context of a supporting component framework too. However, there is a rapidly growing number of modern technology platforms which have to coexist with mature but legacy technology. To cope with that challenge the Model-Driven Architecture paradigm was created. The idea is to use a hierarchy of platform-independent models of applications and application domains. Transformation rules allow the generation of platform-dependent code from models. That might work well for newly built systems, but how to include legacy systems or off-the-shelf components in this paradigm? We will discuss a much simpler approach - a platform-independent markup-language for components and a set of tools to support classical round-trip engineering.