Undefined segments cause the application to stop currently.

e.g.

else {
      /**
       * TODO Remove this and add a default segment parser
       * This is mainly in place so we can see what default
       * segments we are missing
       */
      var e = new Error('Invalid segment type: '+s)
      e.code = 'EINVSEGTYPE'
      e.raw = data
      if process.env.IGNORE_HL7_MISSING_SEGMENTS == true  
        console.error e
      else
        throw e
    }

Stops after a message or two...

Does it just parse the messages or does it create a server like this module:
https://github.com/ekryski/node-hl7
Which port is it using then?

Would be awesome to add a basic example with a test message to the readme (I found this one, but I'm still confused: http://evanlucas.com/nodengine-hl7/).

I don't see the project running under a special license here on Github, but I've seen that the segments are under copyright. On NPM it is under GNU license, with the restriciton to modify the code:
Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. So I guess I can use this in a commercial project? Than I would also contribute to the project in JS.

Maybe a good idea to add that.