1.7. Anatomy of a Server Call
At a lower level, how does an Ajax interaction look? Here's a typical sequence of events. Let's begin with the application startup sequence (Figure 1-4):
Figure 1-4. Typical startup sequence
User points browser to Ajax App. The user begins interacting with an Ajax application by visiting it in the usual way; e.g., by following a link or selecting a bookmark.
Once the application has loaded, further activity will be triggered by events. Following is the typical sequence for each event (Figure 1-5):
Figure 1-5. Typical event-handling sequence
Server processes request. In the server, a web service (see the Web Service [Chapter 6] pattern) receives the request.
Server responds. The web service receives the request and outputs a response using standard HTTP techniques that will be familiar to anyone who has worked on traditional web applications.
The sequence gives a quick overview of the technologiesthere's a hands-on introduction to each of them in the next chapter, and the first part of the patterns, Foundational Technology Patterns (Part II) covers them in more detail.