Can microservice-based online-retailers be used as an SPL?

Microservices are deployable software artifacts that combine a set of business features and expose them to other microservices. Ideally, the reuse and interchanging of microservices should be easy as they are supposed to be independent of each other, both conceptually and technologically. Selecting a service to fulfill a given feature (e.g., managing a cart in a website) recalls the way Software Product Lines (SPL) allow variability. However, in practice, interchanging microservices requires knowing the features that the services propose, how they communicate with other services and their types. In this work, we propose to analyze service dependencies as feature dependencies, at the feature, structural, technological, and versioning level, to assess the interchangeability of services. We analyze six community-selected use-cases and report that services are non-interchangeable systematically.