ArcGIS JS API: parse GP Service messages

I am working on a JS app where the user draws a polygon and then a python-based GP Service task queries the parcels and generates mailing labels. The GP task works great, but once the PDF is created I need to open the hyperlink in a new tab.

What I really need to get at is the return of my Python function:

# as a trivial example:
def myFunc(*args):
    # do something
    return output_url  # this is what I want to access!

So in my gp task, the function is returning the hyperlink url needed to download the report. I do not think there is an out of the box way to get the gp result. So the other thing I am thinking is to parse the messages returned from the GP Service. I have looked through the help docs and do not see a sample how to get at the messages. I'm new the JS development, so it's probably there and I'm just missing it. Any help would be appreciated.

My call to the gp task:

var gp = new Geoprocessor("http://ift.tt/1FGDrXV");

function OpenInNewTab(url) {
    var win = window.open(url, '_blank');
    win.focus();
  };  

var gpParams = {
    "Boundary": fs,
    "Site": "Paynesville",
    "Mailing_Type": "taxpayer"
  };
gp.execute(gpParams);
var URL = ""; #need to get this from result OR parse messages

gp.on("execute-complete", OpenInNewTab(URL));

And here is an example of the JSON from the GP service messages:

{
 "results": [

 ],
 "messages": [
  {
   "type": "esriJobMessageTypeInformative",
   "description": "Executing (MailingLabels): MailingLabels \"Feature Set\" Paynesville taxpayer"
  },
  {
   "type": "esriJobMessageTypeInformative",
   "description": "Start Time: Wed Mar 25 11:29:45 2015"
  },
  {
   "type": "esriJobMessageTypeInformative",
   "description": "Executing (MailingLabels): MailingLabels \"Feature Set\" Paynesville taxpayer"
  },
  {
   "type": "esriJobMessageTypeInformative",
   "description": "Start Time: Wed Mar 25 11:29:45 2015"
  },
  {
   "type": "esriJobMessageTypeInformative",
   "description": "Running script MailingLabels..."
  },
  {
   "type": "esriJobMessageTypeInformative",
   "description": "Creating labels in Avery 5160 format"
  },
  {
   "type": "esriJobMessageTypeInformative",
   "description": "\nCreated \\\\arcserver2\\wwwroot\\TempFiles\\MailingLabels_taxpayer20150325112946.pdf\n"
  },
  {
   "type": "esriJobMessageTypeInformative",
   "description": "http://ift.tt/1FGDrXX"
  },
  {
   "type": "esriJobMessageTypeInformative",
   "description": "Completed script MailingLabels..."
  },
  {
   "type": "esriJobMessageTypeInformative",
   "description": "Succeeded at Wed Mar 25 11:29:47 2015 (Elapsed Time: 1.85 seconds)"
  },
  {
   "type": "esriJobMessageTypeInformative",
   "description": "Succeeded at Wed Mar 25 11:29:47 2015 (Elapsed Time: 1.85 seconds)"
  }
 ]
}

There is nothing in the "results", so since I am actually printing out the URL needed in the messages, I'm thinking I can parse these somehow. So my questions are:

1. 
   

   Is there a way I can get the return URL from my Python function back as a result from the GP Service?

   
   


2. 
   

   If the answer to number 1 is no, how do I get at the result messages and step through them? This is a Synchronous task so I am using the execute() method.