Architectural Collaboration in Internal Software Ecosystems

Abstract

Large-scale organizations, such as Siemens, develop a broad field of products for varying domains. Software constitutes a major innovation and cost factor to their development. Organizational-wide reuse of software across products, even across domains, gives these organizations a competitive advantage. This involves large-scale reuse approaches where software is developed in a decentralized manner by several internal, yet self-contained organizational units -- those units are separate profit centers with own business objectives, organizationally independent with own product management, and have widely autonomous processes and software-engineering life cycles. I define those systems as internal software ecosystems. The intra-organizational, yet decentralized development context increases the amount and complexity of dependencies among both software assets and the responsible organizational units. This significantly impacts collaboration in software engineering. Traditional process-centric coordination mechanisms become increasingly inefficient, calling for a suitable software architecture to enable effective collaboration. However, in order to make informed architecture decisions, applied modes of collaboration and resulting architecture challenges must be understood. As first major contribution in this thesis, I provide strong empirical evidence on collaboration and resulting architecture challenges for two of the largest internal software ecosystems at Siemens -- based on a total of 46 hours of semi-structured interviews with 17 leading software architects from all involved organizational units. I identify three collaboration models on a continuum that ranges from high to low coupling and a classification of architecture challenges together with a qualitative and quantitative exposure of the identified recurring hurdles. My results outline a broad field of real-world challenges that need to be investigated by researchers, and my results support practitioners who follow the collaboration models to make informed architecture decisions based on empirical evidence. Besides taking informed architecture decisions, it is equally important to manage and control adherence to the specified architecture at an ecosystem-wide level. However, feature and schedule pressure regularly require to accept architecture violations by several organizational units, which decreases quality and increases maintenance costs. As main finding of my investigation on collaboration and architecture challenges, I identify the explicit and systematic management of architecture violations as the key challenge for internal software ecosystems, in particular the lack of developer support for resolving violations. As second major contribution within this thesis, I elaborate the TrAViM approach, a framework that comprises seven violation-management capabilities for internal software ecosystems. Their main purpose is developer support for resolving architecture violations, aiming to reduce the developers' effort required to handle them. I develop a prototype that instantiates the approach. Using the prototype, I conduct an in-depth case study on the capabilities' usefulness, involving 9 experts from my study systems. All of them expressed that the capabilities are highly valuable and hold great potential to ease violation management for large-scale software engineering.