A Framework for Microservices Synchronization

Microservices architecture and continuous software engineering are becoming pop- ular approaches for developing and operating software products. The enabling feature of this success is the independence of the execution environments hosting microservices: by insulating failures and versioning in specific microservices, a com- plex application benefits of high availability at runtime and agility at development time. However, execution independence does not mean functional independence. Microservices need to interact among them to fulfill a common goal of an appli- cation. The unavailability of a microservice may seriously impact other dependent microservices, limiting continuity. To address this new kind of problem in microser- vices architecture, we argue the necessity of a synchronization mechanism able to support microservices coordination according to their running states: dependent microservices should wait for unready ones to avoid useless and faulty interactions. In this paper, we propose a new framework, Synchronizer, able to support syn- chronization among microservices by exploiting distributed registries for collecting health/state information about deployed containers and hosted microservices. It has been implemented for the OpenShift platform and validated in different use cases: e.g. for coordinating applications bootstrap and for programming scripts of continu- ous deployment orchestrators, such as Jenkins. In both cases, Synchronizer worked as expected and showed the positive effects of synchronization, giving us a valuable feedback about the possibility of further extending its application and of integrating the feature in existing microservices frameworks (e.g. services mesh).