You adopted microservices for independence and agility. Instead, every deployment requires coordinating multiple teams and testing the entire system. What you built is a distributed monolith, complexity spread across systems, but still bound by monolithic coupling. The shift from technical boundaries to business-driven boundaries is the only path to true agility. Many organizations discover too late that microservices alone do not guarantee independence. Domain-Driven Composable Architecture (DDCA) provides a methodology to escape this rigidity. 

This article is a practical playbook for decomposing services into Packaged Business Capabilities (PBCs) aligned with business domains and mapped to AWS patterns such as EventBridge, Step Functions, and DynamoDB Streams. It explains when DDCA fits and when it does not, and covers security, anti-patterns, and operational realities, so you can adopt composability with a clear view of the investment required.