Banking + Eventual Consistency = A Forbidden Love Story
So here’s the deal: eventual consistency and banking systems are basically like that one couple everyone knows about - the kind that’s full of drama and clearly not meant to be, but we just can’t stop watching. It’s like a tragic love story where one side is all chill and laid-back, and the other’s got no time for that. And somehow, they keep trying to make it work. Spoiler alert: it’s not working.
Microservices & High Flexibility (The new dating scene)
Microservices are the fresh, flexible thing everyone’s into now. They’re like the cool singles who don’t need to commit to one big monolithic app. The idea is to break down big applications into smaller, manageable services that can grow or shrink based on needs. It’s fantastic for many modern apps, where things don’t need to be perfect in the moment.
But as soon as you throw in the need for synchronization between services, things get tricky. That’s where eventual consistency comes in - basically saying, “Don’t stress if things aren’t aligned right now. Give it a bit of time, and everything will catch up”. Sounds great for social media posts and online orders, but there’s a catch when you’re talking about banking.
So, why is eventual consistency a bad fit for banks?
ACID vs CAP: The Struggle is Real
Banks are built on trust and precision. When you swipe your card, you expect that payment to go through immediately - no waiting, no “eventually”. So when we talk about eventual consistency, it’s hard to see how it fits into this picture.
For banks, ACID (Atomicity, Consistency, Isolation, Durability) principles are a non-negotiable playbook. This means that everything needs to be 100% accurate and immediate.
Now, here’s the thing: eventual consistency works great in environments where near-perfect data is good enough. Think e-commerce or social media - where slight delays don’t totally break things. It allows for the possibility that things might not align perfectly in real-time. And that’s just not something banks can afford, especially when dealing with people’s money.
Transaction Integrity: Not Optional (A Real Life Example)
Imagine this: you go buy your coffee, swipe your card, and walk away, only to find out five minutes later that it didn’t go through. In banking, that’s a nightmare. Eventual consistency might say, “Hey, don’t worry, it'll catch up”, but that's just not something banks can risk. They need transaction integrity - meaning that if it says you paid, you better have paid. No room for errors here.
Who Needs Drama?
At the end of the day, banks are built on trust. If you can’t trust that the transaction happened the way it was supposed to, your customers will break faster than a couple caught in a love triangle. Eventual consistency might sound great in theory, but when it comes to something as important as your life savings, people are gonna need a bit more than “It’ll all work out eventually”.
So, is there a future for these two?
In short, it’s unlikely these two will live happily ever after. But like any drama, there are twists. Hybrid solutions like event-driven architectures could let them coexist - just not as soulmates. While critical operations like fund transfers demand strong consistency to ensure accuracy and security, less time-sensitive processes, such as account balance updates or transaction history logs, can tolerate eventual consistency.
But let's face it, this sounds more like friends with benefits than the real thing.
Conclusion (A Tragic, but Real Love Story)
Eventual consistency may be perfect for laid-back systems like social media or e-commerce, where things aren’t quite as time-sensitive. But banking needs things to be tight, fast, and consistent - no room for "eventually". It’s a forbidden love story that never really stood a chance, and that’s okay.
Final Thought & Bonus Tracks (and inspiration)
In the end, love might be blind, but banking never will be - it's all about consistency, no drama.
Wale - Love Hate Thing
Jack White - Love is Blindness
