Decompose By Business Capability

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?

Solution

We can define a microservice corresponding to a particular business capability. A business capability refers to the business activity targetted to generate value. A business capability can be referred as business object. For Example −

• Order Management − Order Management Business Capability refers to Orders.

• Customer Management − Customer Management Business Capability refers to Customers.

Business Capabilities can further be categorized into multi-level hiearchical structure. For example, Order Mangement can have delivery, inventory, service etc. as business capabilities.

Example

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

• Books Catalog Management

• Inventory Management

• Order Management

• Warranty Management

Advantages

• Stable Architecture − As business capabilities 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.

Dis-advantages

• Need good understand of Business − Business capabilities 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 capabilities.