# A Systematic Mapping Study on the Modernization of Legacy Systems to Microservice Architecture
## 4 Results
### Main Activities
It is noteworthy that this refinement preserved the fundamental activities and steps identified through research in the extant literature. In this manner, while maintaining the integrity of the original process (first version), some steps were reorganized and/or grouped to optimize the work of the teams responsible for carrying out the modernization. Following this refinement, the process underwent a reduction in steps from 38 to 29, which remained distributed throughout the set of the identified activities, as illustrated in Figure 6. Next, a description of the modernization activities identified in our SMS is addressed, offering a synthesis of the steps within each activity. * Planning. This activity was identified in five studies included in our mapping (i.e., S6, S15, S16, S21, and S33). In essence, planning entails the definition of the objectives, strategies, and resources required to attain the desired outcome, which, in this case, is the modernization of the system. The evidence obtained from our investigation indicates that when planning modernization activities, organizations and development teams are more likely to succeed if they anticipate potential challenges and ensure that objectives are achieved within the specified timeframe and resources. From the perspective of the organization, the evidence suggests that a suitable methodology and appropriate infrastructure must be adopted to conduct modernization practices. With regard to development, the findings of our mapping recommend that teams have cultures around development (e.g., unit testing). In this sense, training can be an effective measure to align the interests of organizations with development practices and facilitate the development and modernization of applications based on microservices. * Analysis. Of the 43 studies included in our mapping, 35 (i.e., S2 to S8, S10 to S13, S16, S18 to S38, S40, S41, and S43) presented concrete evidence related to this activity. In other words, the analysis activity can be considered the initial phase of modernization, as it is during this process that the development team will gain insights into the artifacts of the legacy system, including the binary system, source code repository, and documentation, which can serve as a source of information. Consequently, it is anticipated that a sufficient quantity of information will be amassed to facilitate the formulation of an appropriate starting point for the decomposition process. This encompasses the identification of the disparate components and functionalities of the legacy system, an understanding of its business domain boundaries, and an analysis  
Figure 6: Modernization process. of the dependencies between the aforementioned components. In summary, this step is of paramount importance to the successful migration of the legacy system to microservices, as it establishes the foundation for the design and implementation of this architectural style. * Decomposition. This activity was addressed in five studies (i.e., S3 to S5, S18, S27, and S31) of our mapping. This activity plays a fundamental role in the modernization of legacy systems based on MSA, as it directly influences the decomposition of the legacy system into microservices, thereby giving rise to a novel architectural configuration for the system. From a design perspective, the evidence gathered from our investigation suggests that each microservice should be designed based on the organizational and business aspects that will be offered to users. Furthermore, the evidence indicates that the primary challenge associated with this activity is determining the optimal size for microservices. This is because the legacy system must be divided into smaller units that present low coupling and high cohesion. In other words, each microservice must be responsible for a delimited context, providing a cohesive set of functionalities with a well-defined scope to meet a specific business capability.