StateMachineUsingEvents.js

var _ = require('lodash'),
    events = require('events'),
    inEventEmitter = new events.EventEmitter(),
    localEventEmitter = new events.EventEmitter(),
    outEventEmitter = new events.EventEmitter(),
    jobs = [{
        "name": "scrape",
        "in": ":Editorial:ResearchLink:Added",
        "out": ":Editorial:ResearchLink:Processed",
        "states": [{
                "name": "fetch",
                "to": "extract",
                "config": {},
                "execute": function (config, input, cb) {
                    input.message += "fetch";
                    cb(input);
                }
            }, {
                "name": "extract",
                "to": "persist",
                "config": {},
                "execute": function (config, input, cb) {
                    input.message += "extract";
                    cb(input);
                }
            }, {
                "name": "persist",
                "config": {},
                "execute": function (config, input, cb) {
                    input.message += "persist";
                    cb(input);
                }
            }]
        }];

jobs.forEach(function (job) {

    // bin all incoming global job events
    inEventEmitter.on(job.in, function(data) {
        console.log(job.in);
        var initalState = job.states[0];
        localEventEmitter.emit(initalState.name, data);

    });

    // bind all incoming job internal events
    job.states.forEach(function (state) {

        localEventEmitter.on(state.name, function (data) {
           state.execute(state.config, data, function (output) {
                console.log(job.in + ':' + state.name);

               if(!state.to) {
                   outEventEmitter.emit(job.out, output);
                   return;
               }
               localEventEmitter.emit(state.to, output);

           });
        });

    });

    // bind output job events
    // bind input job processing events
    outEventEmitter.on(job.out, function(data) {
        console.log(job.out);
        console.log(data);
    });
});

inEventEmitter.emit(jobs[0].in, {"message": "text"});
//localEventEmitter.emit('fetch', {"message": "fetch"});
//localEventEmitter.emit('fetch', {"message": "fetch"});
//localEventEmitter.emit('fetch', {"message": "fetch"});
//localEventEmitter.emit('extract', {"message": "extract"});
//localEventEmitter.emit('persist', {"message": "persist"});