Consistency challenges in event-driven microservices: a literature review on data, process, and system evolution

Abstract As event-driven microservice architectures become more prevalent in modern software systems, especially those integrated with business processes, the issue of consistency across distributed components has emerged as a central challenge. Despite extensive adoption, there remains no clear consensus on what microservices are or how consistency should be defined and maintained across such systems. This paper addresses the fragmented understanding of consistency in microservice architectures, aiming to identify how it is conceptualized in the literature and what strategies are used to manage it effectively. The methodology follows the systematic review procedures originally proposed by Kitchenham [1]. The review revealed three dominant categories of consistency: data consistency, process consistency, and system evolution consistency. Each type involves distinct approaches that address specific challenges documented in the literature. These concerns are often addressed in isolation, resulting in a fragmented research landscape. The selection of digital libraries and the exclusion of gray literature may have limited the scope of the review. Future work could expand the dataset and further validate the proposed model. Other categories that are deemed relevant may also be added. Three main originality aspects are identified in this paper as follows: i) the categorization of consistency into the three types; ii) the organization of the main approaches used to address each type of consistency; and iii) the discussion of the relationship between consistency types and the selection of appropriate approaches to guarantee each type.