API or ETL? Choosing the Right Integration Approach

"Should we do the integration over an API, or pull it with ETL?" In ERP projects this question is asked too early and answered too late. The right answer is "it depends"; but to decide based on the situation, you need to know the concrete advantages of all three approaches.

01. REST API: For Instant Flow

A REST API is ideal for instant, synchronous data flow between two systems. A dealer places an order in B2B, and within seconds it lands in the ERP. But API endpoints must exist; if the ERP vendor doesn't provide them, an alternative path is sought.

02. ETL: Batch but Reliable

ETL (Extract, Transform, Load) pulls and transforms high-volume data at set intervals. It's suitable for operations like end-of-day reports and monthly reconciliation. It isn't instant; there's a delay of 15 minutes to 24 hours. Acceptable depending on the case.

03. Message Queue: Outage-Tolerant

Message-queue tools like RabbitMQ, Azure Service Bus and Kafka provide asynchronous but guaranteed delivery between two systems. During an outage, messages wait in the queue and are processed in order once the connection returns. It's the standard for projects that require high volume + high reliability.

04. Hybrid Approach: This Is Real Life

In serious enterprise projects, a single approach isn't enough. API for orders, ETL for the accounting close, a message queue for critical account transactions — the three are used together. The right answer isn't "which one" but "which one in which situation."