Stop 08 · Systems & Technical UnderstandingTopics · 4/9

System Integration Basics

In short

Most projects don't build one system. They connect your app to payments, inventory, CRM, SMS and accounting. Integrations are where the nasty surprises hide, so BAs who ask the right questions early save months.

Understanding how different systems connect and share data with each other — a common source of hidden complexity in requirements, since integrations often reveal constraints nobody anticipated upfront.

The purple blob holds a phone while standing between a stack of plates, a bundle of marigold flowers and a pair of speakers.

Think of it like this

A wedding with many vendors

The caterer, decorator, tent house and band all need the same guest count and timings. If the family updates the count to 400 but only tells the caterer, the tent fits 300. Integration is making sure every vendor gets the same update, in time.

Watch it happen

One order, five systems

Store app

Payment

Inventory

Courier

Accounts

1/5A customer places an order. The store app creates it with status 'pending'.

The big ideas

What you need to know

Who sends what, when

For each link, note the data sent, the trigger, the direction and how often. A simple table works.

One source of truth

Decide which system owns each piece of data, like customer address. Others copy from it.

Real-time or batch

Some data moves instantly, some in nightly files. It changes what users see and when.

Plan for failure

What if one system is down? Retry, queue, alert someone, or stop the order? Write it down.

Save yourself the pain

Common mistakes

Oops

Discovering in testing that the courier system needs a 6-digit PIN code field you never captured.

Do this instead

Get each partner system's required fields early and map them to your data in a field mapping sheet.

Oops

Assuming both systems mean the same thing by 'customer' or 'order date'.

Do this instead

Define shared terms in a glossary and confirm formats, like dates and currencies, on both sides.

Your mission

Draw an integration map

~30 min

Quick check

Your CRM and billing system both store customer addresses, and they often disagree. What's the best fix to recommend?

Go deeper

1Diagram how 2-3 systems in a hypothetical organization might need to integrate.
2Learn why integration requirements deserve extra scrutiny during elicitation, since they're often underestimated.
3Practice asking 'what systems does this need to talk to?' early in a requirements conversation.