Decompose By Subdomain

Problem Statement

Microservice architecture structures an application as a set of loosely coupled microservices and each service should be developed independently in agile manner to enable continous delivery/deployment. When a large, complex application is to be built using microservice architecture, the major problem is how to design loosely coupled microservices or to break a large application into small loosely coupled services?


We can define a microservice corresponding to Domain-Driven Design(DDD) subdomains. DDD refers to business as a domain and a domain can have multiple subdomains. Now each subdomain refers to different areas. For Example −

  • Order Management − Order Management subdomain refers to Orders.

  • Customer Management − Customer Management subdomain refers to Customers.

Subdomains can be further classified using following criterias −

  • Core − Most important and key differentiator of an application.

  • Supporting − Business related and are used to support the business activities.

  • Generic − Not specific to business but are used to enhance the business operations.


Consider an example of an Online Book Store. It can have following subdomains and corresponding microservices −

  • Books Catalog Management

  • Inventory Management

  • Order Management

  • Warranty Management

Decompose By Subdomain Design Pattern


  • Stable Architecture − As business subdomains are stable, this architecture is highly stable.

  • Cross-functional Teams − Development Teams works independently, are cross-functional and are organized around functional features instead of technical features.

  • Loosely Coupled Services − Developed services will be loosely coupled and cohesive.


  • Need good understand of Business − Business subdomains needs be indentified after understanding the business. Understanding organizational structure can help as organizations are structured based on their capabilities.

  • High Level Domain Model needed − Business domain objects required as they corresponds to business subdomains.

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