Question 1

What if the other system has no API?

Accepted Answer

In order: an official API, file-based transfer (SFTP/CSV), or direct read access to the database. If none exist, screen scraping is technically possible but brittle — proposed only as a last resort, with the risk stated in writing.

Question 2

What if the same record transfers twice?

Accepted Answer

Transfers are designed to be idempotent: a repeated record updates the existing one instead of creating a duplicate. This is a precondition for retries — otherwise every retry creates a new problem.

Question 3

Is data lost when a service goes down?

Accepted Answer

No. Requests are queued, transient failures retried with backoff, and permanently failed ones land in a dead-letter queue that raises an alert. A record that vanishes silently is the most expensive kind of integration bug.

Question 4

How is reconciliation handled?

Accepted Answer

Record counts and critical fields on both sides are compared periodically and discrepancies reported. Without it you can't claim an integration is correct — only that it isn't throwing errors.

System Integration & API Development