AHAH after AJAX!!!

Asynchronous HTML and HTTP, or AHAH, is a method for updating webpages dynamically using Javascript, similar to Ajax, but with the difference that the response from the request is used directly without parsing on the clientside. This means that server responses need to be text or already include valid XHTML/HTML structure.

AHAH is intended to be a much simpler way to do web development than AJAX : "Asynchronous JavaScript and XML." Strictly speaking, AHAH can be considered a subset of AJAX, since (X)HTML is just a special kind of XML.

The main reasons that made AHAH exists :

• The lack of custom XML schemas dramatically reduces design time
• AHAH can trivially reuse existing HTML pages, avoiding the need for a custom web service
• All data transport is done via browser-friendly HTML, easing debugging and testing
• The HTML is designed to be directly embedded in the page's DOM, eliminating the need for parsing
• As HTML, designers can format it using CSS, rather than programmers having to do XSLT transforms
• Processing is all done on the server, so the client-side programming is essentiall nil (moving opaque bits)

This is a sample code for sending an AHAH request


function ahah(url,target) {
// native XMLHttpRequest object
document.getElementById(target).innerHTML = 'sending...';
if (window.XMLHttpRequest) {
req = new XMLHttpRequest();
req.onreadystatechange = function() {ahahDone(target);};
req.open("GET", url, true);
req.send(null);
// IE/Windows ActiveX version
} else if (window.ActiveXObject) {
req = new ActiveXObject("Microsoft.XMLHTTP");
if (req) {
req.onreadystatechange = function() {ahahDone(target);};
req.open("GET", url, true);
req.send();
}
}
}



Then to receive an AHAH request


function ahahDone(target) {
// only if req is "loaded"
if (req.readyState == 4) {
// only if "OK"
if (req.status == 200) {
results = req.responseText;
document.getElementById(target).innerHTML = results;
} else {
document.getElementById(target).innerHTML="ahah error:n" +
req.statusText;
}
}
}

If you would like to know more about AHAH you can refer Microformats or else check out the following links

http://en.wikipedia.org/wiki/AHAH

http://www.xfront.com/microformats/AHAH.html