Dissertation: A Theory of Microservice Integration
Abstract
Microservices are an architectural style for building scalable and maintainable software applications. These applications are composed of small and self-contained services that communicate over a network with each other. The loose coupling between microservices supports independent evolution and deployment, allowing teams to adopt the most suitable technologies for each service. However, this decomposition introduces the inherent complexity of the design, implementation, operation, and maintenance of a distributed system. While individual microservices may be simple by themselves, the complexity shifts into the integration layer, where microservices need to interact with each other to provide the functionality of the system. Integration becomes a predominant and continuous challenge and poses a steep learning curve for practitioners. This doctoral thesis develops a theory of microservice integration and codifies it as a practical handbook of integration techniques. The theory is grounded in a multi-method research approach including systematic literature reviews, qualitative surveys via semi-structured expert interviews, action research studies, and a single-case case study. Recognizing integration as a socio-technical topic, the theory includes organizational, architectural, technical, and operational dimensions. Two follow-up studies provide deeper insights into balancing technological heterogeneity and microservice contract testing. Finally, a prototype tool for decentralized documentation illustrates how the integration techniques can inform future tool development. Researchers can build on our findings to explore integration challenges more deeply and refine our results with subsequent evaluation and validation studies. For practitioners, the handbook offers actionable guidance to address integration challenges in industry. The results of this thesis highlight the growing importance of socio-technical factors in the evolution of microservice architectures, especially as modern tools and technologies continue to reduce purely technical barriers.
Reference
Georg Schwarz (2025). A Theory of Microservice Integration. Friedrich-Alexander University Erlangen-Nürnberg.
Committee
Rüdiger Kapitza (chair), Dirk Riehle (supervisor), Antonio Rito Silva (reviewer), Georg Fischer (member)
Dissertation
PDF available soon.