Ash Framework•2w ago

When to use Ash.Oban vs Ash.StateMachine

have a very simple pipeline that needs to be durable, i.e. automatic retry. I am porting a Python code that uses Temporal.io durable execution.
I am not sure if I have to use Oban or StateMachine, when is each more suitable?

Solution:

in general combining ash_state_machine and ash_oban to trigger state transitions is one of my favorite combinations of Ash features out there

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7 Replies

ZachDaniel•2w ago

Generally speaking, I would suggest using them together actually 😄 ash_state_machine is only about the rules about what transitions can be made

Solution

ZachDaniel•2w ago

in general combining ash_state_machine and ash_oban to trigger state transitions is one of my favorite combinations of Ash features out there

FredOP•2w ago

Got it. I have to look for an example of this working somewhere. I am very newbie and a lern-by-example learner.

ZachDaniel•2w ago

Yeah, this is something it would be great to have a full-blown example of TBH but I'm not sure if such a holistic example exists

ZachDaniel•2w ago

state_machine do
  default_initial_state :pending
  transition :send_package, from: :pending, to: :en_route
  transition :delivered, from: :en_route, to: :delivered
end

actions do
  create :create do
    accept [:destination]
  end

  update :send_package do
    # this action is called by the trigger
    change ... # logic to actually send a package
    change transition_state(:en_route)
  end

  update :delivered do
    # maybe some API trigger does this when package is delievered
    change transition_state(:delivered)
  end
end

ash_oban do
  triggers do
    trigger :send_package do
      where expr(state == :pending)
    end
  end
end

state_machine do
  default_initial_state :pending
  transition :send_package, from: :pending, to: :en_route
  transition :delivered, from: :en_route, to: :delivered
end

actions do
  create :create do
    accept [:destination]
  end

  update :send_package do
    # this action is called by the trigger
    change ... # logic to actually send a package
    change transition_state(:en_route)
  end

  update :delivered do
    # maybe some API trigger does this when package is delievered
    change transition_state(:delivered)
  end
end

ash_oban do
  triggers do
    trigger :send_package do
      where expr(state == :pending)
    end
  end
end

FredOP•2w ago

I can start with a state_machine and just use oban afterwards... seems a baby step.

ZachDaniel•2w ago

Yep! You can even start with a state machine with no data layer and just test transitions and then add persistence with a data layer and then add automation with ash_oban

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When to use Ash.Oban vs Ash.StateMachine

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