Custom software for companies and government

06 · Engineering

From requirement to screen

How a system is born here, shown through a real case: the path of an order in WhatsBar, from the waiter’s phone to the owner’s dashboard.

1. 1

   The waiter sends the round

   From a phone, on Wi-Fi or 4G. The screen only displays: price, availability and permissions are decided by the server.

2. 2

   The order is created once

   Each round carries a key. If the network drops and the waiter taps “Send” again, the same order comes back, never a second one.

3. 3

   Each station gets its own

   Items are split by production station and stock is deducted through the recipe sheet, in a single transaction.

4. 4

   A printer never blocks the sale

   Tickets go through a queue outside the transaction. A printer that is off delays the paper, not the order.

5. 5

   The owner sees the whole floor

   Revenue, average ticket, payment methods and sales per waiter, while the shift is running.

-- one round, one order
orders
UNIQUE (establishment_id, idempotency_key)

-- one ticket, one agent
UPDATE print_jobs
SET status = 'printing'
WHERE id = ? AND status = 'queued'

That is the standard: business rules live on the server, failure is anticipated before it happens and every decision has a test that proves it. It works the same for a bar, a legislative office, a clinic or a city hall.