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rightbyte

Having cashier machines that does not work offline is a bad idea. Closing almost all stores sounds expensive.

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The payment terminals should work in non-integrated mode. Every restaurant does this.

Could even do offline simple verification of payment with the debit/credit happening at a later time.

> Every restaurant does this.

I think you'll find that it varies throughout the world. In Sweden, I've been to a couple of restaurants when their payment network was down and had it not been for them also being hooked up to the Swish app (which is connected to a separate payment network), no one during those lunch seatings would've been able to pay at all (both of these were cash-less restaurants, which are super common in Sweden, where almost no one uses cash anymore, sadly*).

Just to give you a picture of how seldom we come into contact with cash here: The Swedish Central Bank redesigned the artwork and form factor of the hard currency here, I think even introduced some new denominations, back in 2015. 6 years later, I still haven't seen or touched one of these new bills or coins out in the wild. That's how much people use cash here.

*: I may lament it, but I'm the same. It's so damn convenient, but I am of course aware of the drawbacks.

Couldn't they still just write down the transaction details, get a signature, and process later?

That's a traditional payment system where you hand off your card to some waiter who then sketchily takes off with it and does who-knows-what with it and returns it along with your receipt.

The modern ones have these portable card terminals that are chip+PIN only. These customers would have to come back another day to pay.

My peer comment: https://news.ycombinator.com/item?id=27722910

> I've been to a couple of restaurants when their payment network was down

Visa and MasterCard EMV have offline transactions baked in. Your bank could disable it on your card, but then you wouldn’t be able to buy a beer on an airplane.

I’m not sure if all terminals can be configured this way (or more likely, if anyone nearby would know how), but the functionality is baked into the visa and MasterCard standards.

But it seems like there’s only a few manufacturers of payment terminals out there and they just interface to the POS.

Here’s a popular US/Canadian restaurant software with instructions on how to put your payment terminal into store-and-forward mode when network/wifi goes down: https://www.touchbistro.com/help-articles/offline-payments-i...

One interesting point: "If processing is offline, the approval process will take longer. It may take up to 1-2 minutes before the card is approved."

I guess the cryptographic verification is slow, at least for that particular implementation.

I would think that in a grocery store, the registers are deeply integrated with the inventory control. That's not needed in a restaurant, registers just collect cash/card.

So, in the former, catching up is much harder - you might need to take an inventory if the outage is lengthy, which is a PITA. The requirements probably didn't include offline mode.

You're assuming the inventory records are ever coming back.

It's not given that the cashier machines are the reason they are staying closed. Coop has a database that maps all items they sell to the corresponding price. What if they aren't sure about the integrity of it, and the possible offline copies that the stores have. That would be a very good reason to keep closed. After all, you wouldn't want to sell steak for the price of potatoes.

It isn't that long since i've seen Norwegian cashier machines running in offline mode. While Norway isn't Sweden. I'm under the impression that our payments systems are almost identical.

In Sweden pretty much everything is done online in these kind of businesses. And I don't think you can do it in another way since it is a bit of franchise model.

Almost every transaction at a place like this will be with a card. I'm not even sure if most Swedes have enough cash on them to deal with with.

Anecdata, but I live in Sweden and haven't touched cash in well over a year.

Anecdata 2, same in Denmark, I've lived here more than 5 years and have seen local cash maybe once.

I don’t even know which denominations our cash uses now. For example is there a 100 bill or was it replaced with the 200?

But as we see here it doesn’t matter whether I use cash since stores close when the systems go offline anyway. I doubt they’d even set up a cash fallback if this continues for months.

That is surprising, most Swedes have to use cash when they go to Spain for holidays. But, I guess that this pandemic year checks out. :)

Sweden uses Krona, Spain uses Euro. You might have a few Euro laying around for when you travel (most likely you just get some at the airport just before boarding to Spain), but in Sweden Euro is almost useless.

At least in Germany, cards also work offline if necessary.

So when there's an outage you can buy whatever you want? Or how do they verify that you have money?

I guess you're too young to remember when ALL transactions involved trust. Cheques didn't even have any kind of verification whatsoever, you just handed them out and the shops had to just hope they would clear... if they did not, the payee could obviously get into trouble with the law, but criminals still found creative ways to get away with it... watch the movie "Catch me if you can" to see one of the most entertaining abuses of cheques in history.

Once the transaction goes through your account at the bank (in case of debit) will be overdrawn and the bank will charge a penalty sum/interest as well as asking you to put funds in to get it back to a positive balance again.

Almost all Visa/Mastercard cards support this. It's actually better with chip cards since they're MCUs, capable of storing data including offline 'credit limits' and tabulating how much has been debited offline. Can verify pins offline too.

When you buy food/beer on a plane/train, this is probably happening. Ryanair would rather eat the cost of a fraudulent payment than pay for data and slow down their salespeople.

When I paid with a semi-broken machine recently, I actually had to sign a slip. I think the machine just read my IBAN as if the chip was a magnet strip. The offline credit limits are more of an optimization.

It's only 800 stores :)

That would be more than the number actually branded as Coop which is 665 [1] so yeah that'd be all of them plus some of their acquisitions like the 165 Nettos [2]. Sweden is a country of only 10 million by the way.

[1]. https://www.coop.se/butiker-erbjudanden/vara-butiker/

[2]. https://sv.wikipedia.org/wiki/Coop_Butiker_%26_Stormarknader

The netto branding has been removed, in all places I have seen

How would you propose recording electronic payments and linking data back to restock/procurement while offline?

Couch/Pouch

offline-first PWA

Manual fallback option when the most predictable failure scenario happens (only backend server fails)

Like they used to do it? Store the transactions locally and send them later. Taxis still do that with their terminals.

A credit card imprinting machine [1], and paper records of inventory change that can be uploaded afterwards.

[1] https://www.youtube.com/watch?v=a7wutgAlNHk

A few years ago, during a power outage, a stores clerk actually used one of these for/on me. I was pretty shocked ;)

Most of my cards don’t have embossed numbers these days.

Strange, I think all credit (not debit) cards here do. Might be regional.

In sweden they don't - at least not on the debit cards, which are common. They also just removed the holder's signature field too, nobody ever uses that (it's authenticated with pin + optional ID).

I'm in the US - my latest Mastercard has chip and stripe, but no embossing. The number, exp, and cvv are all on the backside.

The embossing is a convenience. The clerk writes the number in the space provided if there is no embossed number.

They did the same thing in the 70's if your card was worn down. This is a solved problem.

1. Require cash.

2. Have clerks write down what is needed on the shelfs.

Cash is incredibly rare in Sweden these days.

But Swish (mobile payments) could work.

>1. Require cash.

They'd have to make that very clear at the entrance to the store. This is just a guess, but I think most Swedes don't carry enough cash to even pay for groceries when they go shopping. I haven't had any paper money in years, just a few coins.

Cash makes up less then 15% of transactions in my country. It would be less disruptive to just close the store.

But if the store in question would accept cash, then it could at least server some of its customers. I expect it would not only be 15% of the customers. I would add those customers who are, you know, a little capable of adapting to circumstances and would actually go to their ATM to pick up some cash if they don't have any in their wallet. If not, I guess they don't need those groceries so urgently.

> go to their ATM

I think you're underestimating how little we use cash. There aren't even ATMs in some parts of town and there are plenty of villages without one for tens of miles. Nobody uses cash anymore. It's all either debit cards or direct transfers (either via and app or the bank.)

Treat it as "card not present". Write down the card number, expiration, cvv, name, and zip or equivalent. Get a signature and process it later. If you can't process it later, your system design is flawed.

This is not that hard. Each store can keep a local record of what is going on. Back in the "dark ages" this was done anyway, credit card transactions were settled at the end of the day. Inventory at a physical location can be tracked locally and updates sent to a central system later to figure out what needs to be restocked where.

Unlike other distributed databases you don't have one store selling an item of food from another store (especially if your online system is down) and need to do a split brain recomp.

Enough people rely on debit cards nowadays that only work online that it would still cause significant disruption. Enough that it's probably not worth keeping the stores open until it can be fixed.

Many card machines can work 'online' but not using the stores own servers.

I don't even know a single person with a credit card here. Everything is done with debit cards which require being online to check the balance and reject the transaction if it's insufficient.

Distributed databases are cool.

There are a couple of approaches that could involve multiple payment providers over redundant networks so switch to something else.

For inventory, since it’s likely only temporary transactions can be stored locally and then synced when back online.

Theoretically the design could be distributed all the time and just keep working the same while disconnected with some potential reorders and restocks slowed down or delayed.

Or, you know, blockchain inventory or something.

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