AJAX - The Complete Reference

498 Part III: Advanced Topics

myXML.load(url);

}

static function main()

{

ExternalInterface.addCallback("connect", null, connect);

}

}

You should, after your inspection, notice a connect() method that takes a url and a

callback that is invoked upon success. This method has been exported to an included Web

page as indicated by the line ExternalInterface.addCallback("connect", null,

connect).

Now we need to convert this ActionScript into a Flash SWF file. Even if we don’t have

Flash, there are a number of ActionScript compilers on the Internet to do this. We compiled

the example using one called mtasc (www.mtasc.org):

mtasc -version 8 -header 1:1:1 -main -swf ajaxtcrflash.swf ajaxtcrflash.as

The 1:1:1 makes the SWF file a 1px × 1px running at 1-frame per second movie. Our goal

here is a bit unusual for Flash, to be invisible and behind the scenes to the user.

Next, we take our created SWF file and insert it into the page. The syntax to do this for

plug-in-focused browsers like Firefox is primarily using an <embed> tag like so:

<embed type="application/x-shockwave-flash" src="http://ajaxref.com/

ch10/flash/ajaxtcrflash.swf" width="1" height="1" id="helloexternal"

name="helloexternal" />

Microsoft’s ActiveX component technology would prefer to see the Flash specified like

so, using the <object> tag:

<object id="helloexternal" classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000"

width="1" height="1" >

<param name="movie" value="http://ajaxref.com/ch10/flash/ajaxtcrflash.swf" />

</object>

Due to some unfortunate lawsuits regarding the use of binary objects within browsers,

we have to use script code to insert these elements lest we get a prompt to “Activate this

control” in the Microsoft browser. We create a simple function to do just that:

function createSWF()

{

var swfNode = "";

if (navigator.plugins && navigator.mimeTypes && navigator.mimeTypes.length)

swfNode = '<embed type="application/x-shockwave-flash" src=

"http://ajaxref.com/ch10/flash/ajaxtcrflash.swf" width="1" height="1"

id="helloexternal" name="helloexternal" />';

else { // PC IE

swfNode = '<object id="helloexternal" classid="clsid:D27CDB6E-AE6D-11cf-

96B8-444553540000" width="1" height="1" >';

swfNode += '<param name="movie" value="http://ajaxref.com/ch10/flash/

ajaxtcrflash.swf" />';