Wrapping an external service...

CardReader.js

var EventEmitter = require("events").EventEmitter;
var util = require("util");

module.exports = CardReader;

//the export is essentially a self-healing wrapper around the external interface...
function CardReader() {
  var that = this, someProc = null;
  loadProc();
  function loadProc() {
    someProc = loadExternalProc();
    someProc.on('exit',function(err){
      //log error etc...

      //reload external proc
      loadProc();
    });

    //for each instance event, bind a passthrough.
    someproc.on('something',function(){
      that.emit.bind('something').apply(arguments);
    });

  }

}

util.inherits(CardReader,EventEmitter);

function loadExternalProc() {
  //run your external script that may fail here...
}