Exploring the Code for This Example

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

//Create a YUI instance including support for cross-domain IO:
YUI().use("io-xdr", "node", function(Y) {
    // Y is the YUI instance.
    // The rest of the following code is encapsulated in this
    // anonymous function.
} );

//Configure the cross-domain transport:
var xdrConfig = {
    id:'flash', //We'll reference this id in the xdr configuration of our transaction.
    src:'io.swf' //Relative path to the .swf file from the current page.
};
Y.io.transport(xdrConfig);

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.

//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");
}

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:

//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.one('#zip').get("value");

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

    //The Yahoo! Weather feed.
    var entryPoint = 'http://weather.yahooapis.com/forecastrss';

    //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
            }
        }
    );
}


//Add the click handler to the Get Weather RSS button as soon
//as the Flash transport has loaded, indicated by the firing
//of event "io:xdrReady".
Y.on('io:xdrReady', function() {
    var btn = Y.one("#getWeather");
    btn.set("disabled", false);
    //Use the Event Utility to wire the Get RSS button
    //to the getModule function.
    Y.on("click", getModule, "#getWeather");
});

Full Script Source

Here is the full JavaScript source for this example:

<form id="wForm">
<fieldset>
    <label>Zip Code or Location ID</label> <input type="text" id="zip" value="94089">
    <p>Please enter a U.S. Zip Code or a Location ID to get the current temperature.  The default is Zip Code 94089 for Sunnyvale, California; its location ID is: USCA1116.</p>
</fieldset>
<div id="weatherModule">
    <li>Weather RSS data will appear here.</li>
</div>
<input type="button" value="Get Weather RSS" id="getWeather" disabled="disabled">
</form>


<script language="javascript">

YUI({ filter:'raw' }).use("io-xdr", "node",

    function(Y) {

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

        //Configure the cross-domain transport:
        var xdrConfig = {
            id:'flash', //We'll reference this id in the xdr configuration of our transaction.
            src:'io.swf' //Relative path to the .swf file from the current page.
        };
        Y.io.transport(xdrConfig);

        //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.one('#zip').get("value");

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

            //The Yahoo! Weather feed.
            var entryPoint = 'http://weather.yahooapis.com/forecastrss';

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

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

            //Make the request:
            var request = Y.io(sUrl, {
                method:"GET",
                xdr: {
                    use:'flash', //This is the xdrConfig id we referenced above.
                    dataType:'xml' //Indicate the data are XML, not string.
                },
                on:
                    {
                        success:successHandler,
                        failure:failureHandler
                    }
                }
            );
        }

        //Add the click handler to the Get Weather RSS button as soon
        //as the Flash transport has loaded:
        Y.on('io:xdrReady', function() {
            var btn = Y.one("#getWeather");
            btn.set("disabled", false);
            //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");
    }
);
</script>