Promises and challenges of microservices: an exploratory study

Microservice-based architecture is a SOA-inspired principle of building complex systems as a composition of small, loosely coupled components that communicate with each other using language-agnostic APIs. This architectural principle is now becoming increasingly popular in industry due to its advantages, such as greater software development agility and improved scalability of deployed applications. In this work, we aim at collecting and categorizing best practices, challenges, and some existing solutions for these challenges employed by practitioners successfully developing microservice-based applications for commercial use. Specifically, we focus our study on "mature" teams developing microservice-based applications for at least two years, explicitly excluding "newcomers" to the field. We conduct a broad, mixed-method study that includes in-depth interviews with 21 practitioners and a follow-up online survey with 37 respondents, covering 37 companies in total. Our study shows that, in several cases, practitioners opt to deviate from the "standard" advice, e.g., instead of splitting microservices by business capabilities, they focus on resource consumption and intended deployment infrastructure. Some also choose to refrain from using multiple programming languages for implementing their microservices, as that practice hinders reuse opportunities. In fact, our study participants identified robust and shared infrastructural support established early on in the development process as one of the main factors contributing to their success. They also identified several pressing challenges related to the efficient managing of common code across services and the support of product variants. The results of our study can benefit practitioners who are interested to learn from each other, borrow successful ideas, and avoid common mistakes. It can also inform researchers and inspire novel solutions to some of the identified challenges.