In Chapter 15 we saw how Ajax can enhance your user's experience by making asynchronous requests for information. In that chapter we focused entirely on client-side Ajax. In this chapter we'll focus on using Ajax to communicate with programs on webservers, which I will also call server-side programs.
This chapter explains:
What server-side programs can do for you
Different types of requests
The basics of PHP, a server-side programming language
How to use PHP to read and save files on webservers
What to do if the webserver you are contacting doesn't respond
How to update the contents of a web browser automatically when a server-side file changes
Almost all examples of Ajax on the Web involve ...