Using Database Schemas of Legacy Applications for Microservices Identification: A Mapping Study.

The extraction of software components or services from a legacy system, is a very active field of research especially after the introduction of the microservices architectures. There are many different proposed approaches to solve this complex problem with the help of static and dynamic analysis of the source code, domain driven business dataflow diagrams etc. When we are dealing with a legacy system (e.g., a system with monolithic architecture) the most common asset that we inherit, aside from the application's code itself, is the database schema and its data. The source code isn't always available for analysis and the dataflow diagrams although helpful to some extent, they do not provide any reuse of the system's source code. The purpose of this research is to systematically identify primary studies that are using the database artefacts for microservice extraction, analyse the type of the artefacts and the degree they are used, and lastly investigate if the proposed methods support automation. We will then try to verbally analyse their viability in a real world scenario based on our many year experience working with legacy systems. In the context of this research, we conducted a systematic mapping study regarding the usage of database artefacts for the identification of components or services. This article presents the results of this study. Our future research goal is to use the database schema, state of data, dependencies, foreign keys etc., for identifying discrete business units within the legacy system database. Each such unit will have loose coupling with other units and be highly cohesive making it a potential microservice.