Using LoadVars sendAndLoad instead of WebService when calling web services with Flash ActionScript

I’ve ran into issues using the WebService object in Flash.  The thing is incredibly buggy.  In certain cases, it works just fine, but in other cases, it flat out does not work. In my last case, the web service loaded perfectly fine (onLoad was called), but the PendingCall would not return anything.  The onFault method was never called after I invoked my web service call, but the web service never returned either.  Examining the outgoing messages from Flash (using HTTP headers in Firefox) revealed that Flash was never even attempting to call the web service.  Flash did correctly acquire the crossdomain.xml file (which allowed access from all domains), and it did load the WSDL.  But, for whatever reason, it did not call the web method like it was supposed to.

Well, after a few hours or attempging to make this work, I gave up with the WebService object.  Instead, I went to the LoadVars object, something I’m more confident in than the WebService class, simply due to the fact that it has been around much longer and has had more attention from the Adobe / Macromedia team.

Using the WebService object, my code looked like the following:

var _wsdl:String = ""; // <- this is fake for the purpose of this blog 
var MailService:WebService = new WebService(_wsdl);
MailService.onLoad = function()
  var MailServiceResult:PendingCall = MailService.MyMethod("my parameters"); 
  MailServiceResult.onFault = function(fault)
    trace("it never gets here even though it fails!");
  MailServiceResult.onResult = function(result)
    trace("it never got here either!");

The above was replaced with the code below, and it works perfectly fine:

var result_lv:LoadVars = new LoadVars();
result_lv.onData = function(responseStr:String)
  if(responseStr == undefined)
    trace("Error occurred!");
    trace("Success... parse my data below...");
var send_lv:LoadVars = new LoadVars();
send_lv.myWebServiceParam1 = "param 1";
send_lv.myWebServiceParam2 = "param 2";
send_lv.sendAndLoad("", result_lv, "POST");

Oh, and make sure that if you do this with your web service, that you have the following line in your web.config file.  Otherwise, you won’t be able to access it using these methods (you should be familiar w/ it anyways if you use Ajax to call web services).

    <add name="HttpGet"/>
    <add name="HttpPost"/>

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