The integration problem.
WHAT HAPPENS WITHOUT INTEGRATION
The same data entered several times Figures disagreeing between systems Delay between an event and its effect elsewhere Effort spent reconciling
WHAT MANUAL RE-ENTRY COSTS
Time, errors, and delay.
WHY ERRORS MATTER MORE THAN TIME
They propagate, and are discovered later at greater cost.
WHAT INTEGRATION PROVIDES
Data flowing automatically One place where each fact is entered Consistency between systems
WHAT IT COSTS
Development or configuration Ongoing maintenance Failure when either system changes
WHY THAT LAST POINT IS UNDERESTIMATED
Integrations break on upgrades, and nobody owns them until they fail.
WHAT TO ESTABLISH FOR EVERY INTEGRATION
Who owns it How failure is detected Who is notified
WHAT TO DECIDE
Which system is authoritative for each kind of data.
WHY THAT MATTERS MOST
Without it, conflicting updates produce inconsistency nobody can resolve.
WHAT THAT IS CALLED
The system of record.
WHAT TO DOCUMENT
For each entity: which system owns it, and which receive it.
WHAT TO AVOID
Bidirectional synchronisation without a clear owner.
WHY
Conflicts are inevitable, and resolution rules become arbitrary.
