Database Reference
In-Depth Information
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Every class member access is valid.
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The applet cannot create disasters in its own namespace.
Security Manager
The security manager performs the final set of checks. The
security manager is responsible to preserve thread integrity—to ensure that code in
one group of threads does not interfere with code in another group, even if the two
groups belong to the same parent applet.
The security manager watches out for dangerous operations that could cause
potential damages. The security manager monitors such operations closely. Every
time the applet wants to perform any such operation, it must gain permission from
the security manager. Specifically, the security manager must concur with attempts
by the applet to access any of the following:
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Network communications
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Protected information including the hard drive or private data
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Programs and processes at the level of the operating system
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The class loader
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Libraries of Java classes
Generally, an applet is prevented from the following actions:
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Loading libraries
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Defining method calls
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Starting other programs on the client
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Reading or writing files on the client machine
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Making network connections to machines other than the one from where the
applet emanated
CHAPTER SUMMARY
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Static web pages are no longer adequate for today's information requirements;
Web and database technologies had to be integrated.
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The basics: the Internet is a collection of interconnected networks; a URL acts
as an address on the Web; you use HTML to create web pages; HTTP is the
object-oriented protocol for exchanging web pages.
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A static web page displays the same information every time it is accessed; a
dynamic web page customizes and shows changed content based on requests.
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HTML is simple and straightforward but has many inadequacies. XML over-
comes the deficiencies and provides a better solution.
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An intranet is a private network based on the communication standards of
the public Internet. An extranet is open to selective access by users outside an
organization.
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The Web has become the cornerstone of electronic commerce. Databases are
the centerpieces of electronic commerce. Web-database integration makes elec-
tronic commerce possible.
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