Microservices: The Evolution and Extinction of Web Services?

In the early 2000s, service-oriented architectures (SOA) emerged as a paradigm for distributed computing, e-business processing, and enterprise integration. Rapidly, SOA and web services became the subject of hype, and virtually every organization tried to adopt them, no matter their actual suitability. Even worse, there were nearly as many definitions of SOA as people adopting it. This led to a big fail on many of those attempts, as they tried to change the problem to fit the solution. Nowadays, microservices are the new weapon of choice to achieve the same (and even more) goals posed to SOA years ago. Microservices ("SOA done right") describe a particular way of designing software applications as suites of independently deployable services, bringing dynamism, modularity, distributed development, and integration of heterogeneous systems. However, nothing comes for free: new (and old) challenges appeared, including service design and specification, data integrity, and consistency management. In this chapter, we identify such challenges through an evolutionary view from the early years of SOA to microservices, and beyond. Our findings are backed by a literature review, comprising both academic and gray literature. Afterwards, we analyze how such challenges are addressed in practice, and which challenges remain open, by inspecting microservice-related projects on GitHub, the largest open-source repository to date.