Variability management meets microservices: six challenges of re-engineering microservice-based webshops

A microservice implements a small unit of functionality that it provides through a network using lightweight protocols. So, microservices can be combined to fulfill tasks and implement features of a larger software system---resembling a variability mechanism in the context of a software product line (SPL). Microservices and SPLs have similar goals, namely facilitating reuse and customizing, but they are usually employed in different contexts. Any developer who has access to the network can provide a microservice for any task, while SPLs are usually intended to implement features of a specific domain. Due to their different concepts, using microservices to implement an SPL or adopting SPL practices (e.g., variability management) for microservices is a challenging cross-area research problem. However, both techniques can complement each other, and thus tackling this problem promises benefits for organizations that employ either technique. In this paper, we reason on the importance of advancing in this direction, and sketch six concrete challenges to initiate research, namely (1) feature identification, (2) variability modeling, (3) variable microservice architectures, (4) interchangeability, (5) deep customization, and (6) re-engineering an SPL. We intend these challenges to serve as a starting point for future research in this cross-area research direction---avoiding that the concepts of one area are reinvented in the other.