MSA Decomposition Pattern - Decompose by Subdomain

Problem

Decomposing an application using business capabilities might be a good start, but you will come across so-called "God Classes" which will not be easy to decompose. These classes will be common among multiple services. For example, the Order class will be used in Order Management, Order Taking, Order Delivery, etc. How do we decompose them?

Solution

For the "God Classes" issue, DDD (Domain-Driven Design) comes to the rescue. It uses subdomains and bounded context concepts to solve this problem. DDD breaks the whole domain model created for the enterprise into subdomains. Each subdomain will have a model, and the scope of that model will be called the bounded context. Each microservice will be developed around the bounded context.

Note: Identifying subdomains is not an easy task. It requires an understanding of the business. Like business capabilities, subdomains are identified by analyzing the business and its organizational structure and identifying the different areas of expertise.

The subdomains of an Order management include:

·         Product catalog service

·         Inventory management services

·         Order management services

·         Delivery management services