We've covered the basics, and now you know everything you need to get started using web services. It was the norm awhile ago to call a web service from a server script; the script would collect the data from the service, do its thing, and then send a new page to the client. It worked, at least as far as the user was concerned, as any other page on the Web did, so there was no way for him to know a web service was involved with this process.
Just like everything else, though, Ajax brings about new and fresh ways to look at existing technologies. Data gathered from a web service can now be placed on a page without an entire page reload, as you already know. The "wow" can be put into using web services, and they have a real place in web applications (and in particular, Ajax applications) today.
For the most part, any client request for a web service is
handled in one of two ways. Requests are made using a hidden
<frame> element to handle the
sending and receiving, and then the data is collected from the
frames. Or, a call is made to a server script that handles the
sending and receiving, and the client gets the data from the
server-side script's response.
There are exceptions, ...