Domain-Driven Design Representation of Monolith Candidate Decompositions Based on Entity Accesses

TL;DR

This paper introduces a DDD-based modeling extension for microservice decomposition tools, enhancing visualization and understanding of monolith to microservice migration through formalized DDD concepts.

Contribution

It extends the Mono2Micro tool with a DDD modeling language, CML, to better represent and analyze candidate microservice decompositions from monoliths.

Findings

Improved mapping of candidate decompositions to DDD concepts

Enhanced visualization of microservice candidates

Validation through case study on real-world monolith

Abstract

Microservice architectures have gained popularity as one of the preferred architectural approaches to develop large-scale systems, replacing the monolith architecture approach. Similarly, strategic Domain-Driven Design (DDD) gained traction as the preferred architectural design approach for the development of microservices. However, DDD and its strategic patterns are open-ended by design, leading to a gap between the concepts of DDD and the design of microservices. This gap is especially evident in migration tools that identify microservices from monoliths, where candidate decompositions into microservices provide little in terms of DDD refactoring and visualization. This paper proposes a solution to this problem by extending the operational pipeline of a multi-strategy microservice identification tool, called Mono2Micro, with a DDD modeling tool that provides a language, called Context Mapper DSL (CML), for formalizing the most relevant DDD concepts. The extension maps the content of the candidate decompositions, which include clusters, entities, and functionalities, to CML constructs that represent DDD concepts such as Bounded Context, Aggregate, Entity, and Service, among others. The results are validated with a case study by comparing the candidate decompositions resulting from a real-world monolith application with and without CML translation.