SWX: SWF Data Format

The SWX class also provides a fault handler that you can use to handler errors during SWX RPC calls. To test it out, modify your code so that it matches the listing below:

import org.swxformat.SWX;
 
var swx:SWX = new SWX();
swx.gateway = "http://localhost:8888/php/swx.php";
swx.encoding = "GET";
swx.debug = true;
swx.timeout = 2; // seconds
 
var callParameters:Object =
{
    serviceClass: "Calculator",
    method: "addNumbers",
    args: [35, 7],
    result: [this, resultHandler],
    timeout: [this, timeoutHandler],
    fault: [this, faultHandler]
}
 
swx.call(callParameters);
 
function resultHandler(event:Object)
{
    status.text = event.result;
}
 
function timeoutHandler()
{
    status.text = "Call timed out!";
}
 
function faultHandler(event:Object)
{
    status.text = event.fault.message;
}

And modify your class so that it generates an error:

<?php
    class Calculator
    {
        function addNumbers($n1, $n2)
        {
            return $n3; // $n3 does not exist!
        }
    }
?>

Test your FLA and you should get something along the lines of Error 8: Undefined variable: n3 in /htdocs/swx/trunk/php/services/Calculator.php, line 7 in the status text field in Flash.

The fault handler also returns API-specific fault codes (e.g., Flickr API error codes) back to Flash.

Ideally, you should not have to manually create movie clips and work with low-level native constructs like loadMovie() when working with SWX RPC on a daily basis. The SWX ActionScript Library gives you an abstract, high-level interface for working with SWX RPC.

To use this high-level interface, you need to instantiate the SWX class.

Modify the code listing so that it matches the one below:

import org.swxformat.SWX;
 
var swx:SWX = new SWX();
swx.gateway = "http://localhost:8888/php/swx.php";
swx.encoding = "GET";
swx.debug = true;
 
var callParameters:Object =
{
    serviceClass: "Calculator",
    method: "addNumbers",
    args: [35, 7],
    result: [this, resultHandler]
}
 
swx.call(callParameters);
 
function resultHandler(event:Object)
{
    status.text = event.result;
}

When you run the above example, you should again see 42 in the status text field. Let's look at what has changed.

The biggest change is that you are actually instantiating the SWX class and setting certain properties there (such as the gateway URL, encoding method and whether you want debug information for calls).

Instead of putting call-related parameters directly into a movie clip (you can delete the dataHolder movie clip now as you aren't using it any more), you create a callParameters object and specify the serviceClass, method, and args properties there. But you can do more, you can also specify a result handler that will get called once the data has loaded.

The result handler receives an event object as an argument. That event object has a result property that points to the loaded data.