Why an offline order doesn't print twice

What an offline order is

An offline order is an order your team enters when the restaurant's internet is down. It doesn't go through the cloud: it's handled by the print app, the program that runs on a computer, a Raspberry Pi or an Android phone inside the restaurant, on the same network as the thermal printer. The print app serves a local page over the restaurant's Wi-Fi, prints the ticket right away and keeps the order in a queue on the device itself.

The unique key is born along with the order, inside the print app: a random code that never repeats and stays attached to that order forever. It travels with it in the queue and with every attempt to send it. When the connection comes back, the first thing qmen.us does is check whether that restaurant already has an order with that key. If it does, it replies that it's a duplicate and creates nothing. If it doesn't, it creates the order already marked as printed in the kitchen, and doesn't generate any printing for it.

Why it's always a single ticket

• There's only one paper ticket. During the outage, the print app does the printing, right there in the kitchen. When syncing, the cloud creates the order with no print job attached, so there's no second copy popping out of nowhere half an hour later.
• Resending is safe. The print app only crosses the order off the queue when the cloud confirms. If the answer gets lost along the way, it tries again, the cloud replies that it's a duplicate and the print app takes that as confirmation. A repeated order in the queue doesn't become a repeated order in the kitchen.
• The database guarantees it. The unique-key rule applies to the whole restaurant: even if two sends arrive at the same instant, only one becomes an order.
• The order arrives with the right history. The time recorded is when the waiter entered it, not when it synced, and the price is what was on the saved menu at that moment: the cloud doesn't recalculate anything.

How it works without internet, in 7 steps

There are seven steps, from the warning banner on the phone to the order showing up in the kitchen without a second paper ticket.

1. Recognize that the internet is down

   A banner appears at the top of the waiter app: No internet — tap to open offline mode. If the page won't open anymore, the phone shows the No internet screen with the Open offline mode button. Both lead to the same place: the print app's local page.

2. Open the print app's local page

   It's an address on the restaurant's network, like http://192.168.0.50:8765/, opened in the phone's browser — there's no app to install from a store. The top shows qmen.us — offline mode (no internet). If a notice about an unsaved menu appears, it means that device has never synced the menu; it needs to have been online at least once.

3. Choose the waiter and the table

   The page opens with Waiter, Table, Order name (optional) and PIN, if the restaurant uses one. Tap Start. The lists come from the menu saved at the last sync, with categories, sizes and flavors.

4. Build the order and tap Send and print

   Tap the items, adjust quantity and notes in View order and finish with Send and print. The ticket prints at the prep station's printer right away and the screen confirms with the order's local number, in the format OFF-1, OFF-2, OFF-3. That number belongs to the print app, so the team can keep track while the internet is out.

   Tip: If printing fails, the page warns you and the order doesn't go into the queue. That's on purpose: better to enter it again than to send the cloud an order nobody saw on paper.

5. Let the unique key do the work

   The instant the ticket prints, the order goes into the local queue with its key. The queue is stored on the device, so the power can go out, the phone's browser can close or the print app can restart: the key is still there, unchanged.

6. Wait for the internet to come back

   The print app tries to connect every few seconds, on its own. As soon as the connection comes back, it sends the whole queue at once and updates the saved menu. Nobody needs to press anything or remember to sync at closing time.

7. Check in the kitchen and on the Dashboard

   Each accepted order shows up right away on the station's kitchen display, at the guest's table and on the owner's Dashboard, with the items already sent. What you won't see is paper printing again: these orders come in marked as already printed and qmen.us sends nothing to the printer.

Frequently asked questions

Glossary

Offline mode

A section of the print app's settings that makes it serve a local ordering page and keep a queue while the restaurant has no internet.

Print agent

The small program that runs on the kitchen's device, fetches tickets from qmen.us, prints them on the thermal printer and confirms.

Print app local page

An address on the restaurant's network, like http://192.168.0.50:8765/, that opens in the phone's browser and stands in for the waiter app while there's no internet.

Unique order key

A random code the print app creates for each order taken without internet. It's how the cloud recognizes an order that already came in and doesn't print it again.

Print app queue

A list of orders stored on the restaurant's own device, crossed off only once the cloud confirms it received them.

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