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and viewing the results of your request from your server (see Figure 2.8).
Figure 2.8:
Standard client/server exchanges involving static HTML pages.
Now ask yourself this question: How often do you request information from the same
site? For example, how often do you go visit a site like cnn.com?
Every time you visit it,
you hope that the contents of the same site have changed, say for news updates or stock
quotes or for sports scores/updates/highlights. In this example,
you are interested in
dynamic
information. You are primarily interested in getting the raw information (scores,
stock quotes, news updates), but the server sends you a complete HTML page in which
most of the page consists of formatting information (see Figure 2.7). The information
you’re interested in getting is probably only a few kilobytes at most,
but the formatting
information can be as large as several orders of magnitude times the necessary content
(logos, styling information, advertisements).
Beyond that, how much can you really do with the information that a server sends you?
Let’s say you’ve requested the names and e-mail addresses of a series of vendors. If the
list
is really long, you have to manually sift through the information to find a particular
piece of information. If you’re lucky, the content provider gives you some sort of an
advanced search or sort feature that forces the server
to regenerate an HTML page
organized the way you want it (sorted on a particular field name); but more often than not,
that’s wishful thinking. If the information were in a tabular form,
you could copy and paste
the data into an Excel spreadsheet and perform sorting, but then you need Microsoft
Excel. That’s not a complete solution. Why can’t you just
rearrange things in your
browser?
How does XML figure in here? Most of the discussion surrounding this is contained in
