<style type="text/css" scoped>
#output li {margin-left:2em;}
#output { background-color:#FFFFFF; border:1px dotted #666666; padding:1em; margin-top:1em;}
</style>
<div class="intro">
<p>In the example below, IO is employed to make a cross-domain request to <a href="http://pipes.yahoo.com">Yahoo! Pipes</a>. The output of the Pipe is an RSS-style feed formatted as JSON. We pass that output to the JSON Utility's `parse` method for sanitization and then display the contents of the Pipe in a list.</p>
<p>This example demonstrates how IO can use the Cross-Origin Resource Sharing (http://www.w3.org/TR/cors/) mechanism for making cross-domain requests.</p>
<p><strong>Please note: </strong> All the browsers listed in the Browser Test Baseline (http://developer.yahoo.com/yui/articles/gbs/) support CORS with the exception of IE 6.0 and IE 7.0, and Webkit on iOS 3. In addition to browser capability, the requested resource must respond with the proper Access-Control headers for the request to succeed.</p>
</div>
<div class="example">
{{>io-xdr-source}}
</div>
<h3 class="first">Implementing a Cross-Domain Request for JSON Data</h3>
<p>In this example, we begin with a YUI instance that loads the <code>io-xdr</code>, <code>json-parse</code>, <code>substitute</code> and <code>node</code> modules. The <code>io-xdr</code> module is the key module. The other modules are used to process and output the results:</p>
```
//Create a YUI instance including support for IO and JSON modules:
YUI().use("io-xdr", "substitute", "json-parse", "node", function(Y) {
// Y is the YUI instance.
// The rest of the following code is encapsulated in this
// anonymous function.
});
```
<p>We'll also get a Node reference to the container we'll be using to output the data we retrieve:</p>
```
//element #output:
var output = Y.one("#output ul");
```
<p>handleSuccess is the function responsible for handling the response data. The first thing we do is sanitize the data to ensure we have valid JSON.</p>
```
var oRSS = Y.JSON.parse(o.responseText);
```
<p>Next, we create a simple markup template and use Y.Lang.substitute to fill in the data, as we iterate through the JSON and output the results.</p>
```
//From here, we simply access the JSON data from where it's provided
//in the Yahoo! Pipes output:
if (oRSS && oRSS.count) {
var s = "<!--begin news stories fetched via Yahoo! Pipes-->",
//t in this case is our simple template; this is fed to
//Y.Lang.substitute as we loop through RSS items:
t = "<li><a href='{link}'>{title}</a>, {pubDate}</li>";
for (var i=0; i<oRSS.count; i++) {
s += Y.Lang.substitute(t, oRSS.value.items[i]);
}
//Output the string to the page:
output.set("innerHTML", s);
output.addClass("yui-null");
}
```
<p>Create the configuration object for the cross-domain request, setting up the event handlers and instructing IO to use the browser's native cross-domain transport.</p>
```
var cfg = {
method: "GET", //If omitted, the default is HTTP GET.
xdr: {
use:'native'//For browsers that support CORS.
},
on: {
//Our event handlers previously defined:
start: handleStart,
success: handleSuccess,
failure: handleFailure
}
};
```
<p>Create an event handler that will make the IO call to Yahoo! Pipes when the Load button is clicked:</p>
```
//Wire the button to a click handler to fire our request each
//time the button is clicked:
var handleClick = function(o) {
Y.log("Click detected; beginning io request to Yahoo! Pipes.", "info", "example");
// Remove the default "X-Requested-With" header as this will
// prevent the request from succeeding; the Pipes
// resource will not accept user-defined HTTP headers.
Y.io.header('X-Requested-With');
var obj = Y.io(
//this is a specific Pipes feed, populated with cycling news:
cfg
);
}
//add the click handler to the Load button.
Y.on("click", handleClick, "#pipes");
```
<h4>Full Script</h4>
<p>The full script source for this example is as follows:</p>
```
{{>io-xdr-source}}
```