Migrating the American express payment network, twice
americanexpress.io
americanexpress.io
I’m surprised a network so sensitive to latency (as are payment networks), was able to achieve their latency SLAs with micro services.
Maybe Amex being a closed-loop network helps with latency?
Since the advent of e-commerce, POS-networking and fraud detection systems in 1990's-2000's.
User-facing and authorisation path are highly latency sensitive. It includes tap-to-pay, online checkout, issuer authorisation, fraud decisioning, and instant payment confirmation – even moreso for EFT payments.
> […] 2-5 seconds more from card presentation to getting approval back.
This is the mid-1990's level QoS when smaller merchants connected the acquirer bank via a modem connection, and larger ones via ISDN.
Today, payments are nearly instant in most cases, with longer than one-second card payment flows falling into the exceptions territory or inadequate condition of the payment infrastructure.
I’ve heard anecdotally that it’s < 140 ms for payment networks.
Anyone, please correct me if you know better.
In practice, the POS sends a message to the acquirer processor -> hits the network -> is sent to the issuer processor, and back again.
https://medium.com/wharton-fintech/the-anatomy-of-the-swipe-...
In EU they use of offline PIN was used massively before PSD2 and contactless, that made the terminal request during the time it took for validating the transaction online, and basically as soon as the PIN was ok'ed by the card that confirmed the transaction. That gave a perception of speed.
Now it's basically online PIN mostly or contactless, but that means you perceive a "wait for an ok", that you had before but was masked by the PIN capture and check on device/card.
So we went a bit backwards for cards, but wallets like ApplePay went a bit forward. You win some you lose some I guess
Apple Pay is extremely fast from my experience (at least the web version). There is a high percentage of market loss if payments take long or fail. Im sure there must be a graph for where it plateaus with diminishing returns when it comes to speed but faster payments definitely help with sales.
Yes, this is a huge deal. VisaNet and friends have to wait on the actual bank cores in order to perform online authorization. Amex can guarantee end to end latency.
There's ton of logic on non-critical path that can be extracted to other microservices and called asynchronously - settlements, refunds, rewards, all management and reporting functionalities - to name just a few.
I had no idea that was a thing
> No logic, no message parsing, just simple forwarding.
Quite apart from fraud/abuse prevention, I expect part of this is stuff like juggling all the different rewards and points systems plus handling time-based offers ("spend $x at y retailer by z date, get $10 cash back" type thing) plus ensuring that all those things are correctly unwound in the case of refunds being issued.
As someone who recently got an Amex card (primarily for Air Canada lounge access), I've been impressed at how nice their app is compared to the five previous Canadian bank apps I've been exposed to in recent years (Scotia, BMO, RBC, Tangerine, CIBC). Some nice things I noticed in the Amex CA app that I haven't previously experienced:
- instant alerts on use, even when it was a non mobile pay transaction
- up to the minute transaction history in-app, including Aeroplan point accrual; all my other credit cards have a delay before new items appear.
- an in-app button to debit my bank for the balance without me having to go to my bank's app to send a bill pay.
?!? Are you saying that Amex is the first Canadian credit card you've used to let you make the payment from on its app, with Amex pulling the funds from your bank? Other Canadian credit cards all require you to "push" payments to them via your bank's billpay? This astounds me.
Same with everything else: power, water, taxes, mortgage, all of these I have to look up the number and arrange a bill-pay push, I think only my mobile and internet provider are able to just debit my bank acct directly.
It's atrocious how bad most bank and card apps are. I'm planning a switch to a new bank, and mobile app quality is a huge criterion. Bank of America and Wells Fargo get zero points from me.
migrating services is easier if your DB supports those things and is more oriented around AP
now a lot of people just jump straight to microservices without considering what their DB can do for them, or if at times they need a relational DB, or if their use case can be served by a hybrid Db.
if you see most of the talks at Monster Scale [0]: They're around DBs
but also
> Latency, throughput, and resiliency characteristics had to remain consistent, and in some cases improve.
> Payment requests could not be dropped, delayed, or left unanswered.
what else would an "anomaly" be?
Hmmm.
Oh Jesus Christ.