JavaServer Pages

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This basic activity has many variations. The data being requested by the browser may
come from a user typing a URL (universal resource locater) directly, may be in response
to the user's clicking a link, or may be automatic, such as an image contained within a
page. In each case, the server will receive a properly formatted request for the data, no
matter how the request is generated on the client.
How the server fulfills this request also has many variations. In the simplest model, the
response may come from a file. Often, there is a simple relationship between URLs and
such files. For example, the URL
http://somesite.net/lyrics/This_Ascension/forever_shaken.txt might come from a file
called C:\Webfiles\This_Ascension\forever_shaken.txt on the computer called
somesite.net.
However, just as the server does not care how the request is generated, the client does not
care how the response is constructed. Storing data in a file is perfectly adequate for
information that never changes, such as the lyrics to a song, or that doesn't change very
often, such as a band's tour schedule. When a new date is added to such a schedule,
someone can simply edit the file by using a text editor, such as emacs, vi, or notepad, or a
full HTML editor, such as Dreamweaver.
However, the file-based model does not work for information that changes very rapidly
or that requires input from the user. Following are a few of the ways in which a site might
need to take input from a user.
·
Many Web sites are dedicated to getting stock quotes, and these sites are used by
uncountable numbers of people. If Web servers could do no more than send files
around, every site would need to have a separate file for every single stock in
existence. The result would be a huge set of files, and it would be difficult, if not
impossible, to keep them all updated.
·
Although many e-commerce companies have gone out of business, e-commerce
itself is thriving, and the electronic shopping cart is now commonplace. This
activity would also be completely impossible without the ability to run programs
on the server. A site could still put its catalog online as a collection of files, but it
takes a program to keep track of what items have been ordered, as well as to
connect with the shipping and inventory systems to send the merchandise to the
user.
·
You are here: CodeIdol > Java > JavaServer Pages > page: 11 12 13 14 15 16 17 18 19 20 21

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