What
is a Web Database?
A
web database is an organized listing of web pages. It's like the card catalogue
that you might find in the library. The database holds a "surrogate"
(or selected pieces like the title, the headings, etc.) for each web page. The
creation of these surrogates is called "indexing", and each web
database does it in a different way. Web databases hold surrogates for anywhere
from 1 million to several billion web pages.
Why
Web Database?
The
current web is largely based on file system technology, which can deal well
with the resources that are primarily static. However, with unprecedented
growth of resources, it is no longer adequate to rely on this conventional file
technology for organising, storing and accessing large amount of information on
the web. Thus, many websites turn towards database technology to keep track of
the increasing amount of data.
Role
of databases in Web applications
Many
organizations offer products through their Web sites, and customers can place
orders by visiting a Web site. For such applications a URL must identify more
than just a file, however rich the contents of the file; a URL must provide an
entry point to services available on the Web site
The
use of a Web browser to invoke a program at a remote site leads us to the role of
databases on the Web: The invoked program can generate a request to a database system.
The
diversity of information on the Web, its distributed nature, and the new uses that
it is being put to lead to challenges for DBMSs that go beyond simply improved performance
in traditional functionality. As an example, a user may want to be notified
whenever a new item meeting some criteria (e.g., a Peace Bear Beanie Baby toy
costing less than $15) is ordered for sale at one of several Web sites. Given
many such user profiles, how can we efficiently monitor them and notify users
promptly as the items they are interested in become available?
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