AJAX and PHP

8AJAX GridData grids have always been one of the areas where web applications have had a seriousdisadvantage compared to desktop programs. The fact that the page needed a full reload whenswitching between grid pages, or when updating grid details, harmed the application from ausability point of view. Technically, fully reloading the page has bad effects as well, unnecessarilywasting network resources.But now you know there is a smarter solution to this problem. You can use AJAX to update thegrid content without refreshing the page. You can keep your beautiful design in the client browserwithout even one page blink. Only the table data is refreshed, not the whole page.The novelty in this chapter is that we'll use Extensible Stylesheet Language Transformation(XSLT) T and XML Path Language (XPath) to generate the client output. XSLT and XPath arepart of the Extensible Stylesheet Language (XSL) family. XSLT allows defining rules totransform an XML document to another format and XPath is a very powerful query language thatallows performing searches and retrieving data from XML documents. When used to create webfront ends, XSLT permits implementing a very flexible architecture, in which the server outputsthe data in XML format, and that data is transformed to HTML using an XSL transformation. Youcan find an introduction to XSL in Appendix C at http://ajaxphp.packtpub.com, and a gooddescription at http://en.wikipedia.org/wiki/Extensible_Stylesheet_Language.Note the XSL transformation can be applied at both client side and server side. Theimplementation in this chapter relies on client functionality to perform thetransformation. This doesn't require any special features of the server, but it poses someconstraints for the client. In Chapter 9, you will see how to apply the transformation atthe server side using PHP functionality, in which case you require this feature to beenabled in PHP, but the solution works with any client, as the client receives directly theHTML code it is supposed to display.In this chapter, you'll use:• XSL to generate an HTML data grid based on XML data received from the server.• AJAX to implement the editable data grid. The user should be able to switch betweenproduct pages and edit product details without experiencing any page reloads.