Meeting legacy systems where they are
Lesson 1 of 3 in Enterprise Integration Architectures.
The systems that run an enterprise predate foundation models by decades, and the implication is blunt: the FM comes to them. Three postures do nearly all of the work. API-based integration wraps FM capability behind an interface the legacy stack already speaks — API Gateway in front of Lambda in front of Bedrock, so the mainframe-adjacent middleware just sees another HTTPS endpoint. Event-driven integration goes further and removes the conversation entirely: the legacy system emits events it was already emitting, Amazon EventBridge matches them with rules, and GenAI consumers subscribe — loose coupling, in the exam's own words. Data synchronization patterns close the loop: enriched results land where the old system already reads (its database, its files, its API), so adoption requires no retraining of systems or people.
The AIP-C01 exam guide names the connective tissue for the second posture: API Gateway for microservice integrations, Lambda for webhook handlers (third-party SaaS calls your HTTPS endpoint; the handler validates, transforms, and forwards), and EventBridge for the event-driven spine.
| Posture | Mechanics | Signal phrases in a stem |
|---|---|---|
Synchronous API | API Gateway → Lambda → Bedrock; the legacy caller waits for the answer | "The existing application must call…", "response needed in the same transaction" |
Event-driven | Source emits → EventBridge rules match and route → consumers react; nobody waits | "Loose coupling", "without modifying the legacy system", "react to events", "fan out" |
Webhook inbound | Third-party SaaS calls your HTTPS endpoint → API Gateway → Lambda handler validates and forwards | "When the SaaS platform notifies us…", "receive callbacks from an external system" |
Interactive checkpoint quiz (2 questions) — open this page in a browser to take it.