# A Systematic Mapping Study on the Modernization of Legacy Systems to Microservice Architecture
## 5 Discussion of Results
The majority of the studies focused on conducting case studies (i.e., 36 studies), which may indicate an interest by researchers and practitioners in evaluating the more practical aspects of these initiatives. This focus on practicality is evident in the choice of case studies, which often present situations similar to those that will be found in real-world scenarios. This type of evaluation is regarded as a positive aspect, as it demonstrates the willingness of the stakeholders to assess the efficacy of modernization initiatives in real contexts. Furthermore, it enables stakeholders, such as software architects and developers, to identify potential bottlenecks and areas for improvement in future iterations of the process. Notwithstanding the limited number of studies that did not undertake an evaluation (i.e., two studies), we have classified these studies as academic, indicating that they are in an early stage of development and present challenges for evaluation. On the other hand, it may be surmised that studies/initiatives that have undergone evaluation are more readily accepted for future implementation, given the evident interest on the part of both researchers and practitioners in investigating initiatives designed to modernize legacy systems based on MSA. Quality attributes. The evidence gathered in this study, along with the experiences reported by [PERSON] et al. [16], indicates that quality attributes must be considered a primary element for service-oriented or microservice-based systems. We observed that monitoring, although less than the others, was an activity identified in our SMS as a follow-up measure for the modernized system (see Table 6). In short, monitoring is most often achieved through regular health checks performed on each microservice handled by the monitoring system. Therefore, it is necessary to specify a set of parameters that should be used to determine the health of each microservice in the modernized software according to the needs of each application domain. Among the interests that can be monitored in a modernized system (i.e., microservice-based), performance, reliability, response time, and availability were identified as the quality attributes (see Figure 5) that can be monitored via a dashboard. Therefore, by using a monitoring system to determine the quality level of each microservice, this system can rank each microservice and provide a list of potential microservices that best meet the needs of their users or that need to be scalable. In this direction, as reported in [PERSON] et al. [67], Grafana ([[https://grafana.com](https://grafana.com)]([https://grafana.com](https://grafana.com)), accessed on 26 March 2025) and Wavefront ([[https://github.com/wavefrontHQ/wavefront-spring-boot](https://github.com/wavefrontHQ/wavefront-spring-boot)]([https://github.com/wavefrontHQ/wavefront-spring-boot](https://github.com/wavefrontHQ/wavefront-spring-boot)), accessed on 26 March 2025) are feasible solutions to promote not only the monitoring of the aforementioned attributes but also the full observability of an application based on microservices. More agile problem detection, modernization monitoring, bottleneck identification, and release agility are some of the benefits that can be achieved with the observability of microservice-based applications using the above solutions. Modernization process. The findings of our investigation suggest that there is a growing interest among researchers and practitioners in the modernization of legacy systems based on MSA. The investigation has identified a series of steps, which have been organized into six distinct activities, as illustrated in Figure 6. In this sense, it is worth highlighting the proposition of the process called Micro4 Delphi [9] as an instance of the modernization process outlined in this article (see Section 4.6). Additionally, a case study was conducted to evaluate the behavior of the Micro4 Delphi process concerning the established set of activities and steps.