# A Systematic Mapping Study on the Modernization of Legacy Systems to Microservice Architecture
## 4 Results
### Taxonomy of Initiatives  
In order to respond to RQ1, an analysis of the initiatives proposed by each primary study was conducted. Of the 43 studies selected for analysis, 27 (i.e., 62.79%) reported the development of approaches for supporting modernization (i.e., S2 to S10, S14, S17, S19 to S22, S24, S26 to S28, S30, S31, S34, S36, and S39 to S42). A total of 16.28% of the studies presented evidence on processes for modernization, including S1, S15, S25, S33, S35, S37, and S38. Additionally, three studies (6.98%) proposed methodologies (i.e., S11, S23, and S29) and frameworks (i.e., S13, S16, and S32). Two studies (4.65%) proposed a method to support software modernization based on MSA, and only one study (2.33%) directed its efforts toward proposing a pipeline for supporting modernization (i.e., S12). Figure 2 \begin{table}
\begin{tabular}{l l l} \hline \hline
**ID** & **Reference** & **Year** \\ \hline S35 & [PERSON] et al. [56], Migrating application from monolith to microservices. & 2020 \\ \hline S36 & [PERSON] et al. [57], Migrating Monoliths to Microservices-based & 2021 \\  & Customizable Multi-tenant Cloud-native Apps. & \\ \hline S37 & [PERSON] et al. [58], Monolith Modularization towards Microservices: & 2021 \\  & Refactoring and Performance Trade-offs. & \\ \hline S38 & [PERSON] et al. [59], Monolithic to Microservices Migration Strategy in Public Safety & 2021 \\  & Secretariat of Mato Grosso. & \\ \hline S39 & [PERSON] et al. [60], Open Source Software as the Main Driver for Evolving & 2021 \\  & Software Systems Toward a Distributed and Performant E-Commerce Platform: & \\  & A Zalando Fashion Store Case Study. & \\ \hline S40 & [PERSON] et al. [61], Partial Migration for Re-architecting a Cloud Native Monolithic & 2020 \\  & Application into Microservices and FaaS. & \\ \hline S41 & [PERSON] et al. [62], The Migration Journey Towards Microservices. & 2021 \\ \hline S42 & [PERSON] et al. [63], Towards a Multi-Tenant Microservice Architecture: An & 2022 \\  & Industrial Experience. & \\ \hline S43 & [PERSON] and [PERSON] [64], Transforming monolithic systems to microservices—An & 2020 \\  & analysis toolkit for legacy code evaluation. & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: _Cont._illustrates the distribution of these initiatives by type (on the X-axis) and year of publication (Y-axis). Next, a description of each initiative identified in our mapping is addressed [65]. * Approach. This initiative is characterized by its theoretical orientation, research methodology, and strategies employed to investigate, analyze, and present results. It offers a structured framework for the selection of suitable methods and provides a rationale for the execution of an activity. * Framework. This initiative encompasses a reusable design, whether in the form of a model or code, that can be refined, specialized, and extended to provide a portion of the overall functionality of numerous applications. * Method. This initiative represents a specific technique used to execute a process, activity, or task. This initiative represents a methodical series of steps to be undertaken in order to complete a process, activity, or task. * Methodology. This initiative can be defined as a systematic approach that is centered on the orderly application of a specific collection of tools, techniques, and guidelines to the design of software. * Pipeline. This initiative represents a software or hardware design technique in which the output of one process serves as the input to a second process, which in turn serves as the input to a third process, and so on. This information flow can frequently occur in parallel within a single cycle time. * Process. This initiative encompasses a series of interrelated or interactive activities that are designed to transform the input(s) into one (or more) anticipated output(s). A process can have multiple starting points, a set of activities that can be a partially ordered sequence, and multiple endpoints, as a workflow specification. Figure 1: Yearly and venue distribution of studies.