HTML and CSS Reference
In-Depth Information
Otherwise, plug-ins and other helper applications may provide the ne-
cessary rendering mechanism. Internet Explorer, for example, has its
internal resources play an AVI movie, whereas other browsers rely upon
some third-party software, such as RealPlayer or QuickTime, to show
the movie. The applet model
With Java applets, the browser sets aside a portion of the document dis-
play space. You may control the size and position of this display area;
the applet controls what is presented inside.
The applet is software, an executable program. Accordingly, besides
providing a display space, the browser, in tandem with the client com-
puter environment and resources, provides the applet with a runtime
environment called a virtual machine .
During execution, Java applets have access to a restricted environment
within the user's computer. For instance, applets have access to the
mouse and keyboard so that they may receive input from the user.
Depending on the security policy in place, applets also may initiate net-
work connections and retrieve data from other servers on the Internet.
In sum, applets are full-fledged programs, complete with a variety of in-
put and output mechanisms, along with a full suite of network services.
You may place several applets in a single document; they all execute in
parallel and may communicate with each other. While the browser may
limit their access to its computer system, applets have complete control
of their virtual environment within the browser. The applet advantage
There are several advantages of applets, not the least of which is provid-
ing more compelling user interfaces within a web page. For instance, an
applet might create a unique set of menus, choices, text fields, and sim-
ilar user-input tools different from those available through the browser.
When the user clicks a button within the applet's interaction/display re-
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