Integration starts with a data agreement
Before development, define what data is transferred, which system is the source, who owns the status, how errors are handled and when retries happen.
Without this, even a simple integration quickly turns into manual support.
Statuses matter more than a pretty diagram
The business needs to know what happened to a request, file or event: accepted, under review, processed, rejected or requiring attention.
A status log helps find problems and reduces dependence on message threads.
What to prepare before the start
API documentation, sample requests and responses, test access, authorization rules, rate limits and the list of errors are all useful inputs.
If documentation does not exist, the first stage can be a discovery of the current data exchange.