Both drafts request a subscription with a GET plus a header:
Scroll Request:
GET /scroll/feed/customers
Prefer: stream
Braid Request:
GET /customers
Subscribe:
The author noted that it's hard to get adoption. Well, the reason that Webhooks are so common is that they are bog-standard HTTP. For this to get adopted, we need to put it into bog-standard HTTP. So we need to go to the IETF, and and extend HTTP in a general way to support state synchronization. It should just work for any existing HTTP media type (not just JSON), and any resource/URL (not just special /scroll/* URLs), and any way of marking timestamps (not just the ordered strings proposed in SCROLL).
Then we can bake this stuff into HTTP, and thus into all our bog-standard libraries, utilities, and code, and you won't have to reimplement the same sync-logic-over-webhooks again, and again, and again.
Reach out if you're interested!
And why formalize on HTTP rather than on a similar protocol over websockets?
Just one correction. My spec doesn't force /scroll/ URL's, just proposes it as a convention.
On create a user or invoice for example sometimes it will return an error, yet it actually created the entity. This means you have to check manually after creating everything to know if its created properly.
Then you have the issue that sometimes quickbooks takes a while to update, and locks the company file while it does some background magic. This means you cannot immediately do the existence check, and also sometimes the check errors or times out which essentially means you need to keep checking forever until you can properly reconcile your db against theirs. But with hundreds/thousands of transactions per minute this state is never reached. You perpetually live in a state of trying to catch up but never managing it.
When I brought it up with Quickbooks dev support their response was literally "Its your job to make sure things are created properly in our system".
How did we get to this place where we started putting up with systems that cannot ever be trusted?
But there is no way (for a merchant) to get the latest 'true' state as held by Adyen. So you better hope your data is exactly in sync with the notifications you got from the webhook (which it never exactly is, because there are so so many points of failures, and unlike what this author says, the docs aren't thát well presented to hold the same model as the PSP does. It is often close enough though, but you are constantly gardening your implementation, because the model also changes on their end with little information in the changelogs).
The "latest state" data exists though! If you open the customer portal it is presented to you without problem.
Tried to talk about this on X until the CEO of WorkOS wanted to bring it in private, then proceeded not to help at all. https://x.com/grinich/status/1913035839866835297?s=20
These weaknesses are why we[1] added FIFO endpoints, Polling Endpoints, and what we call "Svix Stream" as ways to do ordered state synchronization (each with its own tradeoffs). This lets people consume the events in the way that best fits their use-case. We are working on more things to make the state sync even easier. I'd love to hear about more challenges people are facing with webhooks, as we want to make these things better.
OP: I'd love to hear more about your thoughts there, and will send you an email in a moment.
P.S, if you're unfamiliar, please check out Standard Webhooks[2]. It's a spec we created to help with signature verification that has been adopted by OpenAI, Anthropic, Google, and many others. We are chipping at one webhook challenge at a time. :)
1: I'm the founder of Svix (mentioned in the post), we do webhooks infrastructure as a service.
With SCROLL, consumers are responsible for choosing when to ask a provider for updates. Without a mechanism for knowing when data has changed, consumers will be forced to be pessimistic and poll providers for new data on some cadence.
I see two issues with the proposal: (1) SCROLL will lead to an increase in unnecessary network traffic for both the consumer and provider, and (2) because a consumer cannot know when data has changed, the lag between a consumer's local model and the provider's data model will be larger when with Webhooks.
1. Long Poll the cursor to pull down the latest events
2. Trigger a long-poll even if in exponential backoff because they shot you a webhook saying 'eTag changed!'
(I'm not serious about 1954 in particular, I am about hoping somebody here knows the CS literature better than me)
One complication in this approach involves access-windows: What if my system is only supposed to be seeing stuff that happened during two separate weeks in the year, because those are the spans when it was subscribed or authorized?
So the data-host would need to maintain a concept of "connection history" for other services, and also use that to filter/modify its real event stream, inserting artificial "initial state" roll-ups of events that happened in dark periods.