Tài liệu Web Client Programming with Perl-Chapter 2: Demystifying the Browser-P1 pdf

Chapter 2: Demystifying the Browser-P1

Before you start writing your own web programs, you have to become

comfortable with the fact that your web browser is just another client. Lots

of complex things are happening: user interface processing, network

communication, operating system interaction, and HTML/graphics

rendering. But all of that is gravy; without actually negotiating with web

servers and retrieving documents via HTTP, the browser would be as useless

as a TV without a tuner.

HTTP may sound intimidating, but it isn't as bad as you might think. Like

most other Internet protocols, HTTP is text-based. If you were to look at the

communication between your web browser and a web server, you would see

text--and lots of it. After a few minutes of sifting through it all, you'd find

out that HTTP isn't too hard to read. By the end of this chapter, you'll be able

to read HTTP and have a fairly good idea of what's going on during typical

everyday transactions over the Web.

The best way to understand how HTTP works is to see it in action. You

actually see it in action every day, with every click of a hyperlink--it's just

that the gory details are hidden from you. In this chapter, you'll see some

common web transactions: retrieving a page, submitting a form, and

publishing a web page. In each example, the HTTP for each transaction is

printed as well. From there, you'll be able to analyze and understand how

your actions with the browser are translated into HTTP. You'll learn a little

bit about how HTTP is spoken between a web client and server.