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The only reason I knew about idempotency is because growing up I was a little shit and I learned that you could break a LOT of electronics by getting it to do a

The only reason I knew about idempotency is because growing up I was a little shit and I learned that you could break a LOT of electronics by getting it to do a second thing midway before finishing doing the first thing. If it had a screen and buttons, I would try to break it. So I started striving for highly reliable systems not because there are professional bad actors out there or spammers or to achieve high performance… but because there’s another little shit out there.

rmbyrro 3y ago
> getting it to do a second thing midway before finishing doing the first thing I'm not sure this is the kind of failure idempotency is design to tackle. Idempotency tackles the issue of handling multiple requests for doing the same thing, isn't it?
- weaksauce 3y ago
  > Idempotency tackles the issue of handling multiple requests for doing the same thing, isn't it? yeah... there should be no extra side effect if you call something more than once on it with the same parameters. ie foo(x) is the same as foo(foo(x)) is the same as foo(foo(foo(x))) or in networking GET x is the same as GET x followed by a GET x etc... the GET request doesn't (*shouldn't) change anything.
- wayfinder 3y ago
  It gave me an intuitive understanding of state machines and idempotency is one solution to transitions. If you start with State A and a call changes it to State B, what does running the call again do? A->B? But you’re already at B. Shit’s going to break. Redesign your system.
  - rmbyrro 3y ago
    In this example, it seems the API should return some 4xx error. If there's a process with two steps, moving from Step A to B requires the process to be at Step A and it's already at step B, it should return an error. At first glance, this doesn't seem the kind of problem that idempotency is supposed to prevent...
    - wayfinder 3y ago
      Instead of idempotency you can return a 4xx error too. You use idempotency because it’s logistically less complicated for the client.

rmbyrro 3y ago

> getting it to do a second thing midway before finishing doing the first thing I'm not sure this is the kind of failure idempotency is design to tackle. Idempotency tackles the issue of handling multiple requests for doing the same thing, isn't it?

weaksauce 3y ago
> Idempotency tackles the issue of handling multiple requests for doing the same thing, isn't it? yeah... there should be no extra side effect if you call something more than once on it with the same parameters. ie foo(x) is the same as foo(foo(x)) is the same as foo(foo(foo(x))) or in networking GET x is the same as GET x followed by a GET x etc... the GET request doesn't (*shouldn't) change anything.
wayfinder 3y ago
It gave me an intuitive understanding of state machines and idempotency is one solution to transitions. If you start with State A and a call changes it to State B, what does running the call again do? A->B? But you’re already at B. Shit’s going to break. Redesign your system.
- rmbyrro 3y ago
  In this example, it seems the API should return some 4xx error. If there's a process with two steps, moving from Step A to B requires the process to be at Step A and it's already at step B, it should return an error. At first glance, this doesn't seem the kind of problem that idempotency is supposed to prevent...
  - wayfinder 3y ago
    Instead of idempotency you can return a 4xx error too. You use idempotency because it’s logistically less complicated for the client.