Legacy systems often accumulate decades of domain terminology shifts, deprecated database columns, and undocumented business rules encoded directly in controller logic. When creating new services alongside these systems, directly referencing legacy database tables or APIs contaminates the new domain models.
The Role of Facades and Adapters
An Anti-Corruption Layer acts as a formal protocol translator. It isolates the internal domain model of modern services from the idiosyncrasies of legacy systems through dedicated adapters, domain translators, and repository facades.
Key Architectural Considerations
When drafting an ACL, architects must decide between synchronous translation adapters and event-driven translation bridges. In low-latency transaction paths, in-process adapter libraries often provide the cleanest abstraction, whereas cross-network asynchronous message translators prevent legacy latency spikes from propagating to modern consumers.