There is an emerging trend of migrating traditional service-oriented monolithic systems to the microservice architecture. However, this involves the separation of data previously contained in a single database into several databases tailored to specific domains. Developers are thus faced with a new challenge: features such as transaction processing, coordination, and consistency preservation, which were previously supported by the central database, must now be implemented in a decentralized, asynchronously communicating, distributed structure. Numerous prior studies show that these challenges are not met satisfactorily, resulting in inconsistent system states with potentially detrimental consequences. Therefore, we propose to design a coordination service that relies on clear event-based and data-centric formal semantics for microservices specifying the interaction of cross-microservice transactions with their respective databases. Furthermore, we provide a formalization of consistency properties and outline how they can be used to support dynamic monitoring as well as enforcement of consistency properties, thereby providing robust microservice systems. The envisioned architecture can significantly alleviate the developers' burden of implementing complicated distributed algorithms to maintain consistency across decentralized databases.