101worker is the modular knowledge engineering component of the 101companies project. It has developed maintainability and performance problems due to growing organically, rather than following best software design practices. This thesis lays out these problems, drafts a set of requirements for refactoring the system and then describes and analyzes the resulting implementation. The solution involves collation of scattered and redundant information, setup of unit and functional test suites and incrementalization of the bus architecture of 101worker.

Software systems are often developed as a set of variants to meet diverse requirements. Two common approaches to this are "clone-and-owning" and software product lines. Both approaches have advantages and disadvantages. In previous work we and collaborators proposed an idea which combines both approaches to manage variants, similarities, and cloning by using a virtual platform and cloning-related operators. In this thesis, we present an approach for aggregating essential metadata to enable a propagate operator, which implements a form of change propagation. For this we have developed a system to annotate code similarities which were extracted throughout the history of a software repository. The annotations express similarity maintenance tasks, which can then either be executed automatically by propagate or have to be performed manually by the user. In this work we outline the automated metadata extraction process and the system for annotating similarities; we explain how the implemented system can be integrated into the workflow of an existing version control system (Git); and, finally, we present a case study using the 101haskell corpus of variants.