Item — HN Reader

We actually have support for that, we just haven't migrated the doc over to v1 yet: https://v0-docs.hatchet.run/home/features/webhooks. We'll send a POST request for each task.

> It is such a better system than dedicated long running worker listeners, because then you can just scale your HTTP workers as needed.

This depends on the use-case - with long running listeners, you get the benefit of reusing caches, database connections, and disk, and from a pricing perspective, if your task spends a lot of time waiting for i/o operations (or waiting for an event), you don't get billed separately for CPU time. A long-running worker can handle thousands of concurrently running functions on cheap hardware.

> I also find that DAGs tend to get ugly really fast because it generally involves logic. I'd prefer that logic to not be tied into the queue implementation because it becomes harder to unit test. Much easier reason about if you have the HTTP endpoint create a new task, if it needs to.

We usually recommend that DAGs which require too much logic (particularly fanout to a dynamic amount of workflows) should be implemented as a durable task instead.

2 comments

Thanks for your response. webhooks are literally the last thing documented, which says to me that it isn't a focus for your product at all.

I used to work for a company that used long running listeners. They would more often than not, get into a state where (for example) they would need to upgrade some code and now they had all these long running jobs (some would go for 24 hours!), that if they stopped them, would screw everything up down the line because it would take so long to finish if they restarted them that it would impact customer facing data. Just like DAG's, it sounds good on paper, but it is a terrible design pattern that will eventually bite you in the ass.

The better solution is to divide and conquer. Break things up into smaller units of work and then submit more messages to the queue. This way, you can break at any point and you won't lose hours worth of work. The way to force this to developers, is to set constraints about how long things can execute for. Make them think about what they are building and build idempotency into things.

The fact that you're building a system that supports all these footguns seems terrifying. "Usually recommend" is undesirable, people will always find ways to use things in the way you don't expect it. I'd much rather work with a more constrained system than one trying to be all things to all people. Cloud Tasks does a really good job of just doing one thing well.

Admittedly webhook workers aren't exactly this since we send multiple tasks to the same endpoint, where I believe you can register one endpoint per task with Cloud Task. Although, this is not a large change.

I use a router on my end, so it would always be one endpoint anyway. The problem with Cloud Tasks, is that the more individual tasks you create, the more time it takes to deploy. Better to hide all that behind a single router.