Integration complexity arises when a subdomain interacts with many external systems whose interfaces, data formats, reliability, error codes, and failure behaviors differ. Even simple internal domain logic can require substantial transformation and error-handling code. section 10.2.2
Assess integration complexity by examining:
- The number of connected subdomains and systems. section 10.2.2
- The uniqueness or irregularity of APIs and data formats. section 10.2.2
- The reliability, error codes, glitches, documentation quality, and responsiveness of external system owners. section 10.2.2
Holiday booking application
A holiday booking application had straightforward business rules but integrated with more than ten systems for holiday deals and metadata. Each connection required bespoke handling because APIs, formats, errors, glitches, documentation, and developer support varied. section 10.2.2
