Southwest Fox - Day 3, Session 2

Rick Strahl - Introduction to AJAX with Visual FoxPro

Rick started out by telling us what AJAX Asynchronous Javascript and XML (although very little of it uses XML)

In a traditional HTML page any time you need to go back to the database you need a complete redraw of the active page in the browser. AJAX attempts to update the active page without a complete redraw. Rick says AJAX is really Remote Scripting.

Google Maps really started the trend. Many of the web-mail clients use AJAX to display a more windows like interface.

If you have a postback type of page, you can take advantage of AJAX to pull a small piece of data within the context of the active page. One of the things I didn't realize, which is now obvious, is that you can use AJAX to make a plain HTML page dynamic.

In response to a question Rick said that it would be his recommendation to initialize the page with as much data as makes sense instead of for example sending a page with a bunch of empty combo boxes that use AJAX to get the data as the user works through the page.

AJAX is not a replacement for ActiveX or plug-in architectures like Flash. We still can't use AJAX to do things like accessing the local system or uploading files.

Rick mentioned that JavaScript libraries are very important. Rick rolled his own because there wasn't anything reliable when he started getting into this stuff. He mentioned that there are lots of libraries out now and he currently likes jQuery.

Rick then showed us an ASP.NET app that uses VFP COM to demonstrate these concepts. We looked at the HTML and JavaScript used in a simple example.

I had a lot of trouble with my tablet in this session so my motes aren't very complete. I came to this session to get a better understanding of AJAX. I've understood the general concept but didn't really understand how it is implemented. Although we don't have any immediate need to use AJAX with any of our VFP applications, we can probably use it in one of our ASP. NET applications in the very near future, making this session even more valuable.

As always, Rick gave a great session.