YUI Library Examples: IO: XML Transaction — Retrieving a Yahoo! Weather RSS (XML) Feed via a Server-Side Proxy

IO: XML Transaction — Retrieving a Yahoo! Weather RSS (XML) Feed via a Server-Side Proxy

Exploring the Code for This Example

Create a YUI instance, using IO, for this example:

Callback Object and the Weather RSS

Yahoo! Weather RSS will return an XML document if the transaction is successful. The following success callback handlers is used to process the response.

Assemble the Querystring and Initiate the Transaction

The Yahoo! Weather RSS feed requires a simple HTTP GET request with a base URL and a querystring containing the required information as a name-value pair. In this example, we will use the following parameter:

p — location as U.S. Zip Code or Location ID

The following are some example location IDs (do not include the city name):

Beijing: CHXX0008
Helsinki: FIXX0002
London: UKXX0085
Moscow: RSXX0063
Munich: GMXX0087
Paris: FRXX0076
Riyadh: SAXX0017
Tokyo: JAXX0085

For more details on the Yahoo! Weather RSS feed and other location IDs, please visit http://developer.yahoo.com/weather/index.html.

Function getModule retrieves the input values for location and creates a querystring:

Full Script Source

Here is the full JavaScript source for this example:

YUI({base:"../../build/", timeout: 10000}).use("io",

function(Y) {

//Get a Node reference to the div we'll use for displaying
		//results:
		var div = Y.Node.get('#weatherModule');

//Define a function to handle a successful response from
		//Yahoo! Weather.  The success handler will find the response
		//object in its second argument:
		function successHandler(id, o){
			Y.log("Success handler called; handler will parse the retrieved XML and insert into DOM.", "info", "example");
			var root = o.responseXML.documentElement;
			var oTitle = root.getElementsByTagName('description')[0].firstChild.nodeValue;
			var oDateTime = root.getElementsByTagName('lastBuildDate')[0].firstChild.nodeValue;
			var descriptionNode = root.getElementsByTagName('description')[1].firstChild.nodeValue;

div.set("innerHTML", "<p>" + oTitle + "</p>" + "<p>" + oDateTime + "</p>" + descriptionNode);

Y.log("Success handler is complete.", "info", "example");
		}

//Provide a function that can help debug failed
		//requests:
		function failureHandler(id, o){
			Y.log("Failure handler called; http status: " + o.status, "info", "example");
			div.set("innerHTML", o.status + " " + o.statusText);
		}

//When the Get RSS button is clicked, this function will fire
		//and compose/dispatch the IO request:
		function getModule(){
			//Get the input value:
			var iZip = Y.Node.get('#zip').get("value");

//Create a querystring from the input value:
			var queryString = encodeURI('?p=' + iZip);

//The location of our server-side proxy:
			var entryPoint = 'assets/weather.php';

//Compile the full URI for the request:
			var sUrl = entryPoint + queryString;

Y.log("Submitting request; zip code: " + iZip, "info", "example");

//Make the reqeust:
			var request = Y.io(sUrl, {
				method:"GET",
				on:
					{
						success:successHandler,
						failure:failureHandler
					}
				}
			);
		}

//Use the Event Utility to wire the Get RSS button
		//to the getModule function:
		Y.on("click", getModule, "#getWeather");

Y.log("When you retrieve weather RSS data, relevant steps in the process will be reported here in the logger/console.", "info", "example");
	}
);

Proxy and Response

Once weather.php receives the querystring, it will construct and send an HTTP GET using CURL to retrieve the results from the Yahoo! Weather RSS feed. This allows the transaction to succeed while working around XMLHttpRequest's strict security policy.