Custom ERP Integration Spec: API Design Patterns for Legacy System Compatibility
Integration patterns for connecting a modular ERP layer to legacy systems without a full replacement, API versioning, data migration patterns.
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Table of Contents & Section Overview
18 Pages TotalLegacy System Interface Taxonomy
Handling direct SQL connections, flat files, and SOAP services.
Change Data Capture (CDC) Architecture
Syncing database updates in near real time via Debezium.
Idempotent Webhook & Message Queue Design
Preventing duplicate order creation in legacy backends.
Data Schema Transformation Middleware
Mapping legacy column names to modern JSON schemas.
Appendix: Integration Code Patterns
TypeScript and Python adapter code snippets.
Problem Statement
"Directly writing to legacy ERP databases bypasses critical stored procedures and business logic, leading to subtle database corruption and out-of-sync financial ledgers."
Section 2 Excerpt: Change Data Capture (CDC) via Debezium
Rather than polling legacy SQL databases every few minutes (which causes CPU spikes on legacy servers), stream transaction logs using Change Data Capture (CDC) tools like Debezium into Kafka or Redis streams.
This architectural pattern decouples modern custom web interfaces from legacy server workloads, ensuring real-time UI responsiveness while keeping legacy databases completely safe.
Integration Pattern Matrix
| Pattern | Latency | Legacy Server Load | Risk Level |
|---|---|---|---|
| Direct DB Modification | Instant | Low | Extreme (Dangerous) |
| Scheduled Polling | 1-15 Minutes | High (Heavy Queries) | Moderate |
| CDC Event Streaming | <500ms | Negligible | Low (Safe) |
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