SCXML

Use createMachineFromSCXML(...) to create an XState machine from an SCXML document.

Import it from the opt-in xstate/scxml entry point. The XML parser is kept out of the main xstate entry point.

import { createActor } from 'xstate';
import { createMachineFromSCXML } from 'xstate/scxml';

const machine = createMachineFromSCXML(`
  <scxml xmlns="http://www.w3.org/2005/07/scxml"
    version="1.0"
    initial="idle">
    <state id="idle">
      <transition event="START" target="running" />
    </state>
    <state id="running" />
  </scxml>
`);

const actor = createActor(machine).start();
actor.send({ type: 'START' });

The returned value is an XState machine and can be passed to createActor(...), initialTransition(...), and other machine utilities.

Only create machines from trusted SCXML. ECMAScript expressions and <script> elements execute JavaScript in the current environment.

External resources

SCXML can reference external data, scripts, and invoked documents. Provide a synchronous resolveResource function to load those resources:

const machine = createMachineFromSCXML(source, {
  resolveResource: (src, kind) => {
    // kind is "data", "script", or "invoke".
    return resources[src];
  }
});

If an SCXML document references an external resource and no resolver is provided, machine creation throws an error identifying the resource kind and source.

Machine JSON

SCXML is compiled through a private representation because SCXML executable content and transition semantics cannot be represented losslessly as ordinary MachineJSON. Use createMachineFromConfig(...) for serialized XState definitions and createMachineFromSCXML(...) for SCXML documents.

Actor isolation and condition errors

Actors created from the same compiled SCXML machine keep separate transition evaluation state. A failing cond raises error.execution in the current macrostep, even when the condition prevents state entry. Checking snapshot.can(event) does not queue an error for a later real event.