Workflow engine in nodejs

I'm writing a QA bot,

which use expressjs as back-end service, and client use REST to ask question & got reply.

so I'm searching for a workflow engine or a statemachine lib.

had read Workflow engine in Javascript but it seems to use at front-end.

and found a lib noflo , but hard to use for a newbe not familiar with english.

Take a look at https://npmjs.org/package/state.js - this provides a hierarchical state machine based loosely on UML 2 semantics (using 'completion transitions' between states you can achieve workflow-like behaviour).

There's more examples at http://www.steelbreeze.net/state.js/