AHAH: Asynchronous HTML and HTTP or AJA?

AHAH: Asynchronous HTML and HTTP.  Or AJA, as I like to call it; Asyhcrhronous JavaScript And…. :).  Also known as AJAH: Asynchronous JavaScript and HTML.  OK, so we’re just throwing around terms here, but basically it boils down to Ajax without the XML component.

XML is the main communication method over the Internet.  Many applications use XML to transmit data to and from servers and clients.  But is it right for all of us?  There was a nice article about this written at Microformats.  They give nice code examples, but if you already have Ajax implemented, it’s not a long stretch of the imagination.  Before that, let me get into why some people may want to use it.

Whether we like to admit it or not, XML is still just text.  There is no sort of data compression done to make it faster to transfer or anything.  It’s just text.  The advantage, of course, is that it is highly structured.  XML does have its place, but sometimes it is just overkill for simple things.  For example, if the server simply needs to reply with a short “YES” or “NO”, then wrapping these in complex XML tags just packs on much more than is needed.  Also, after being received on the client it, it needs to be decoded and handled.

If you are adding functionality to an existing Legacy Application, like what I’m doing at work, then a plain text response is going to be ideal for you.  Using XML in a case like this is just going to add extra code and processing to decode the XML data sent.  On the server side, functionality also has to be added to send data in XML format.

A developer needs to analyze his particular needs and see whether or not XML data or plain text data is going to be preferable.  Once you have made this decision, on to how you use it.  If Ajax is already implemented, then switching to plain text is a breeze.  When the data is being accessed on the client side, you simply use the responseText property instead of the responseXML.  That’s it.  The response is just going to be a plain text string in whatever format that it was sent from the server.

This approach works perfectly for me, since I use Fast CGI as my backend and there is no native support for XML data.  Also the Legacy Application that I’m working on, works heavily with data formated as simply strings, sometimes delimited by different characters.  If you need more information about plain text messages in Ajax, Ahah, Ajah, (whatever), pay a visit to Ajax Patterns.


  1. […] I came across an page talking about AHAH (Asynchronous HTML and HTTP). I’ve already done an article on this, but this one caught my eye because of his mention about security. […]