Again with the straw man example of a bank transfer.
Another article you didn’t need to read because it talks about a problem you likely don’t have because the author can’t be bothered to come up with actual, real world examples.
Another article you didn’t need to read because it talks about a problem you likely don’t have because the author can’t be bothered to come up with actual, real world examples.
Its true that most people don't need it at all, and I cringe at the thought of a second wave of micro-service muppets stitching it all together with something like this, but there are actually real-world examples. I'm not going to offer you any though, due to your belligerence in the other comments.
A bank transfer is a good example because it is easy to understand, regardless of your background.
Common actions like Create, Delete, and some Updates touch all of these services. Automatic transactions between these would be fantastic. Especially on the billing side, some billing flows involve multiple trips between Stripe and our DB, batching the whole process inside a guaranteed reversable transaction would be lovely.
Of course we're not going to get that with Stripe and Cognito as they expose bespoke API's, but the idea still holds.
Further, those complex interactions between those various services will be much hard to debug and tweak when trying to provide support to end users. Can’t pay your bill because Cognito is down? Can’t grant access because Stripe is down? The data warehouse is doing an index build so you can’t do any transactions? Guess we should turn off the website between 2AM and 4AM ET to allow for data warehouse rebuilds.
There’s a reason we don’t do things this way.
I have had this exact use case in a problem I was solving where the user was waiting at the other end. Please do not presume that only the problems you have solved are worth solving or exist in the real world.
>> Can’t pay your bill because Cognito is down?
I mean, if your AuthN and AuthZ is down, what else would you do ?!!
>> There’s a reason we don’t do things this way.
The smugness in this line is astounding. I don't think I can express how wrong you are.
Minor miscommunication… from a write standpoint. Obviously if you can’t auth, you are in trouble. But if the billing needs to happen so you can restore a permission, then you need to hit a card (for example) and then somehow update your authz service.
In most cases, it’s not strict availability that’s likely your problem (eg. Full down, no responses) it’s going to be business logic or config issues impacting a small subset of TX.
And, honest, if I’m so wrong about this, where is the XA distributed transaction coordinator for Cognito?
I’d be shocked if Amazon ever implemented a single-point-of-failure distributed transaction coordinator and exposed that from their services.
as someone who hasn't implemented transactions in microservices before, I have only seen the bank transfer example and it seems adequate and easy to understand - I wouldn't know what limitations it has
It’s fake. As a result, you can’t actually evaluate the engineering trade offs of the proposed solution.
Here’s the thing: do you even need transactions (in the sense of ACID transactions that are resolved heuristically, as described in this article) between your microservices? Likely not.
And what are the implications of having to wait around for PGSQL and Mongo negotiate a transaction between a third data store? Probably blocking and latency and all the associated problems which will lead to … not use transaction across service boundaries.
Both parties misunderstanding the other is a common trope in movies and novels for a reason.
The unreliable messaging links (internal mail) mean that resilience against missed messages and guards against not making progress must be built into the business process instead of an infrastructure layer.