Information Technology Reference
In-Depth Information
In general, the URL begins with a protocol specification, fol
lowed by a domain name, a specification of directories and possibly
subdirectories, and finally a file name. In some cases, if the file name
is omitted, the Web server will look in the directory or subdirectory
for files by a default name, such as index.html. If you have used the
World Wide Web, then you have typed URLs in searching for vari
ous documents.
An extended form of a URL also is possible. The first part of
this version has exactly the same information (protocol, domain
name, directories, file name) as the URL with which you're familiar.
This information is followed by a question mark and any desired
text. Here is an extended version of the previous example:
info.php?
Computers are useful!!!
Here, the data “Computers are useful!!!” has been added after the
question mark.
When this material is entered into the browser, the browser uses
the first part of the URL to generate the request for the page, just as
you would expect, and the Web server deciphers that material to lo
cate the desired page. However, the browser also packages up the
remaining material and passes that along to the server as well.
When the server processes the material, it identifies the question
mark and then makes the remaining material (after the question
mark) available to the specified Web page. If that page involves run
ning a program at the server, then that program can use the infor
mation as it tries to respond to your request.
For example, if you actually type the previous extended URL into
your browser, the Web server reads the last portion of the URL and
notes that webinfo.php is a program, that program is run, and that pro
gram is given the data “Computers are useful!!!”. In this case, the pro
gram uses that information in deciding what it will place on the page
sent to your browser. With this particular program using this informa
tion, the page displayed in your browser includes the following section:
Query String
Your query string was: Computers are useful!!!
Your query string reversed is: !!!lufesu era sretupmoC
