Effects

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In statecharts, "side-effects" can be grouped into two categories:

"Fire-and-forget" effects, which execute a synchronous side-effect with no events sent back to the statechart, or send an event synchronously back to the statechart:

• Actions - single, discrete effects
• Activities - continuous effects that are disposed when the state they were started in is exited

Invoked effects, which execute a side-effect that can send and receive events asynchronously:

• Invoked Promises - single, discrete effects over time that may resolve or reject once, which are sent as events to the parent machine
• Invoked Callbacks - continuous effects over time that may send multiple events, as well as listen for events sent directly to it, to/from the parent machine
• Invoked Observables - continuous effects over time that may send multiple events triggered by messages from the observed stream
• Invoked Machines - continuous effects represented by Machine instances that can send/receive events, but also notify the parent machine when it has reached its final state