From Practice to Process: Formalizing API-First Design through Method Engineering
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Authors
Beaulieu, Nicole Marie
Issue Date
2025
Type
Dissertation
Language
en_US
Keywords
API Culture , API-First Design , Design Science Research , Microservice Architecture , Software Architecture , Software Engineering Process
Alternative Title
Abstract
The evolution of distributed and cloud-based systems has led the computing community to converge on Microservice Architecture (MSA) as a preferred solution to distributed software design. An expected result of microservice design is a well-defined Application Programming Interface (API) that facilitates access to microservice and system capabilities. Despite the ubiquity of MSA, the availability of software design methods supporting MSA, extensive documentation, and defined frameworks that guide practitioners in implementing microservices, challenges remain in defining concise microservice boundaries and exposing clean APIs for feature access within microservices. In response to these challenges and opportunities, API-First Design (API-FD) is emerging as a viable approach to microservice and distributed system architecture. API-First principles suggest that the capabilities and features of a system are identified early in the design cycle and exposed to external parties (e.g., end-users and third-party developers) via a set or suite of stable, well-defined, and well-documented APIs. The principles also recommend that API consideration, design, and implementation serve as the foundation and core of system design. A significant challenge associated with API-First Design is its infancy, limited peer-reviewed research, and an implied rather than well-defined understanding among industry practitioners and researchers. In this dissertation, we advance the state of API-First Design through rigorous research in the context of multi-client microservice-based systems and, in doing so, provide a research-based foundation that improves its accessibility for our academic peers and industry partners. To build this encompassing foundation, we explore and document the benefits of API-First Design, propose a formal definition for the term "API-First Design," and construct a set of supporting resources: a dictionary, a taxonomy, and a process as the pillars for the adoption of API-First Design as a viable software engineering approach to multi-client MSA and applications. Furthermore, we present our proposed PhiDo API-FD approach and illustrate its use in creating a proof-of-concept software product, a multi-client real estate transaction management solution. Together, these new artifacts and contributions to the art of API-centric design provide a foundational understanding of API-FD and a set of practical tools for both our academic peers and industry collaborators.