Andrew has been developing web sites for over a decade. In that time he has developed and worked on numerous data driven web sites including e-commerce, intranet and online community applications; most were entirely written in PHP. Armed with experience rooted deeply in desktop and server application development using C, C++, Java, and C# he concentrates on making web applications intuitive to the user and manageable for the programmer. His philosophy is that the perfect web page should exist as an extension of the user experience and not separate from it.
However, this is slightly 'stale'. Much of this content can be found elsewhere. There are JS frameworks such as jQuery to support Ajax functions in a cross-browser fashion. Much of the underlying PHP code is just serving/consuming JSON/XML content, and there's tons of code and libraries for that, too.
Contains a curious appendix briefly outlining the differences between PHP 4 & 5. Much of the Internet world has moved onto PHP 5, thanks to its extensive class (OOP) support.
Bottom Line Yes, I would recommend this to a friend
But do you need to buy multiple books to get started? Nah. This shortct is good enough for the beginners.
The most common data that is used with Ajax is XML since it is a standard and most server-side techologies (PHP, ASP, ASP.NET, JSP) can create them for you with various modules/functions. Basically you will have data from a database, retrieve it and create an .xml file from it and then use Ajax to update your web page automatically.
The section (Serving XML - pg 12 - 24) goes throgh this process with code snipets of PHP and various functions to create the XML and serve it to the page. No matter what else you do with Ajax, that is the basics you will need.
If you want the simple facts, the functions and the explanations, then this is a great introduction to get you started with Ajax. It also teaches you a great deal about PHP and the XML modules that are available (SimpleXML).