Context: The popularity of microservices architecture has grown due to its ability to address monolithic architecture issues, such as limited scalability, hard maintenance, and technological dependence. Nonetheless, the migration of monolith systems to microservices is complex. Therefore, methodologies and techniques are needed to facilitate migration and support practitioners and software architects. Objective: The objective of this study is to investigate cases of application migration, microservices identification techniques, tools used during migration, factors that promote migration, as well as issues and benefits of the migration. Method: We have conducted this SMS following the guidelines established by Kitchenham and Petersen. The research objective was defined using part of the Goal-Question-Metric model and the Population, Intervention, and Outcome criteria. From 1546 studies that were retrieved from the search execution , 114 were selected and analyzed to answer the research questions. Results: This SMS contributes with (i) a migration process proposal based on migration cases, (ii) a characterization of migration techniques based on different criteria, (iii) an analysis of tools to support migration, (iv) the identification of migration drivers, and (v) an exploration of migration issues as well as benefits. Conclusion: This SMS sheds light on the complexity and variability of migrating monolithic systems to microservices, as well as the limited number of migration tools. While scalability and maintenance drive migration, few studies assess them. Key challenges include microservices communication and database migration , with most research focusing primarily on monolith decomposition. Despite these difficulties, migration offers benefits, particularly in scalability and maintainability .

The problem of migrating monolithic applications to microservices has become popular both in industry and academia, particularly when using automated tools to assist developers in the decomposition. While a variety of tools and techniques have been proposed, deciding which is the most appropriate decomposition for a given monolith is challenging because the selected technique can return alternative decompositions depending on how the parameters of that technique are configured. This issue has not received enough attention in the literature, and therefore, developers have to resort to their intuition or use the default parameters reported by the authors of the technique. To investigate this problem further, in this work we perform a study of the parameters and variability of the MicroMiner approach, assessing its parameter sensitivity when dealing with two monolithic applications from the literature. Based on a systematic, data-driven analysis of the landscape of possible decompositions, our results show that, depending on the monolithic application provided as input, certain parameters of MicroMiner have more or less importance on the characteristics of the generated decompositions. These findings provide initial guidelines for developers to configure MicroMiner, as well as other approaches, in order to obtain microservice decompositions with relatively low variability.