[en] Component-based software reuse has lead to the emergence of numerous open source software ecosystems. Such ecosystems offer the user a wide and diverse collection of software components that are interconnected by dependency relationships and maintained by large communities of developers. While developers can reuse the work of others by depending on their components, such dependencies give rise to many issues that impact maintenance effort if not properly addressed. This chapter discusses some commonly encountered dependency issues, and illustrates them through two case studies of popular open source package-based software ecosystems: Debian and R. For both of them, we present the limitations of current tool support for dependency management, and we provide results of empirical analyses that highlight how such tool support could be improved.
