The rest of the chapter will build up a sample application, which is a search application for cities of the world.
This example will need a database, and a large data set. I chose a list of city names and their spelling variants as my data set. You can get a list of this type online by searching.
The exact point at which you decide a data set is large enough to require it to be converted to serve over Ajax, instead of being printed fully to the HTML source, depends on a few factors, which are mostly subjective.
A quick test is: if you only ever need to read a few pages of the data, yet there are many pages in the source and the HTML is slow to load, then it's time to convert.
The database I'm using in the example ...