# A Systematic Mapping Study on the Modernization of Legacy Systems to Microservice Architecture
## 4 Results
### Main Activities  
In response to RQ6, this section provides an overview of the methodological process adopted specifically for this question. As reported in Section 1, our investigation was based on a mixed-method investigation composed of a mapping (SMS) and an empirical evaluation by industry practitioners. Next, a description of this process is addressed. Regarding the mapping (SMS), evidence of modernization activities was identified in 40 (93.02%) of the 43 studies included in our SMS. In contrast, no evidence of such activities could be identified in three studies (6.98%), namely, S9, S39, and S42. The evidence extracted from these studies indicates that modernization activities are organized into a process comprising six activities, namely, planning, analysis, decomposition, development, integration, and monitoring. Moreover, this mapping also revealed that each activity consists of a set of steps that must be followed in order to achieve its objective. Table 6 presents the distribution of the most significant studies for this research question, which included three or more activities in their proposed initiatives (see Section 4.2). The data from this distribution reveals the recurrence of the activities in the last row and the number of activities covered by each study in the last column. Notably, S21 is more representative of this distribution by addressing five activities related to the modernization  
Figure 5: Cloud word for quality attributes. of legacy systems with the implementation of MSA. Concerning the extent to which studies adhered to the activities identified in our investigation, it is notable that none of the studies addressed all six activities. In this direction, only S21 covered five activities, four studies (i.e., S18, S20, S27, and S31) presented evidence of four activities, and ten studies (i.e., S6, S7, S13, S15, S16, S26, S28, S35, S41, and S34) reported addressing three activities. Therefore, it can be inferred that 25 studies included only one or two activities. The evidence of this distribution (see Table 6) also revealed that studies of this distribution concentrated their efforts on development (15 occurrences), analysis (14 occurrences), and integration (11 occurrences) activities, respectively. Of the 43 studies included in our mapping, 11 were exclusively dedicated to the analysis of the legacy system and the subsequent development and integration of microservices. Despite the fewer occurrences, activities like planning, decomposition, and monitoring were identified as crucial to the modernization process. These activities facilitate the effective transition of stakeholders, comprising software engineers and domain specialists, from a legacy system to MSA. Based on the findings and insights provided by the scientific analysis, we proceeded to develop the proposed modernization process based on a preliminary step and three interactions with software industry practitioners. As a preliminary step, the first version of the process was formulated after the identification of the essential activities inherent in a modernization process. Each activity is delineated by a series of steps that vary in number and content, ensuring that its objectives are executed in an appropriate manner. For comprehensive guidance on the modernization process, all activities and steps were systematically documented. Regarding the conducting of the activity process, the following points should be highlighted:  
* Cyclical nature. The cyclical nature of software development has been a subject of considerable interest in modern software engineering. According to the principles outlined by [PERSON] [66], incremental processes tend to be more effectively managed and monitored by development teams and stakeholders who have a vested interest in the outcome. Furthermore, the evidence gathered in this SMS reveals that the gradual advancement of modernization also favors the transition between the legacy system and the modernized system, allowing them to act concurrently.