The introduction of Java created the need for additional HTML tags. In
the alpha release of Java, the HotJava browser used the <APP>
tag to include applets within HTML files. However, <APP>
was unacceptable to the standards committee because it could have an infinite
number of parameters. It was replaced by the <APPLET>
tag, used in conjunction with the <PARAM>
tag. Apparently, the standards folks did not like the <APPLET>
tag either, so you can expect it to be replaced eventually, although at
this point, there is no agreement about its successor, and it is highly
unlikely that any production browser would stop supporting <APPLET>.
The syntax of the <APPLET>
tag is shown below; the order of the parameters does not matter:
[ALIGN = alignment]
[ALT = alternate-text]
CODE = applet-filename or OBJECT = serialized-applet
[CODEBASE = applet-directory-url]
[ARCHIVE = filename.zip/filename.jar]
HEIGHT = applet-pixel-height
[HSPACE = horizontal-pixel-margin]
[MAYSCRIPT = true/false]
[NAME = applet-name]
[VSPACE = vertical-pixel-margin]
WIDTH = applet-pixel-width
<PARAM NAME=parameter1 VALUE=value1>
<PARAM NAME=parameter2 VALUE=value2>
<PARAM NAME=parameter3 VALUE=value3>
The <APPLET> tag specifies
where and how to display an applet within the HTML document. If the browser
does not understand the <APPLET>
and <PARAM> tags, it
displays the alternate-html. (It displays the alternate-html because it
doesn't understand the surrounding tags and ignores them. There's
no magic to the alternate-html itself.) If a browser does understand <APPLET>
but cannot run Java (for example, a browser on Windows 3.1) or Java has
been disabled, the browser displays the alternate-html or the alternate-text
specified by the optional ALT
parameter. The CODE, WIDTH,
and HEIGHT parameters are required.
Parameters within the <APPLET>
tag are separated by spaces, not by commas.
Closes the <APPLET> tag.
Anything prior to </APPLET>
is considered alternate-html if it is not a <PARAM>
tag. The alternate-html is displayed when Java is disabled, when Java cannot
be run in the current browser, or when the browser does not understand
the <APPLET> tag.
The following parameters may appear inside the <APPLET>
alignment, optional. Specifies the applet's alignment on the Web page. Valid values are: left,
The alignment values have the
same meanings as they do in the <IMG>
alternate-text, optional. The alternate text is displayed when the browser
understands the <APPLET>
tag but is incapable of executing applets, either because Java is disabled
or not supported on the platform. Support of this tag is browser dependent;
most browsers just display the alternate-html since that is not restricted
filename.zip/filename.jar, optional. Points to a comma-separated list of uncompressed ZIP or JAR files
that contain one or more Java classes. Each file is downloaded
once to the user's disk and searched for the class named in the CODE
parameter, and any helper classes required to execute that class. JAR files
may be signed to grant additional access. ( JAR files are Java archives,
a new archive format defined in Java 1.1. JAR files support features like
digital signatures and compression. While they are not yet in wide use,
they should become an important way of distributing sets of Java classes.)
applet-filename. This parameter or the OBJECT
parameter is required. Name of applet .class
file. The .class
extension is not required in the <APPLET>
tag but is required in the class's actual filename. The filename has to be a quoted string only if it includes whitespace.
applet-directory-url, optional. Relative or absolute
URL specifying the directory in which to locate the .class
file or ZIP archive for the applet. Default: html directory.
applet-pixel-height, required. Initial height of applet in pixels. Many
browsers do not allow applets to change their height.
horizontal-pixel-margin, optional. Horizontal margin left and right of
the applet, in pixels.
applet-name, optional. Allows simultaneously
running applets to communicate by this name. Default: the applet's class name.
serialized-applet. This parameter or the CODE
parameter is required. Name of applet saved to a file as a serialized object.
When loaded, init() is not
called again but start() is.
Parameters for running the applet are taken from this <APPLET>
tag, not the original.
vertical-pixel-margin, optional. Vertical margin above and below the applet,
applet-pixel-width, required. Initial width of applet in pixels. Many browsers
do not allow applets to change their width.
The <PARAM> tag may appear
between the <APPLET>
The <PARAM> tag allows
the HTML author to provide run-time parameters to the applet as a series
of NAME and VALUE
pairs. The NAME is case insensitive,
a String. See Chapter 14, And Then There Were Applets
for a discussion of how to read parameters in an applet. Quotes are required
around the parameter name or its value if there are any embedded spaces.
There can be an infinite number of <PARAM>
tags, and they all must appear between <APPLET>
The special parameter name CABBASE
is used for sending CAB files with Internet Explorer 3.0. CAB files are
similar to ZIP files but are compressed into a CABinet file and can store
audio and image files, in addition to classes. (For a full explanation
When .class files
are placed within a CAB file, they are decompressed at the local end. Here's
<APPLET CODE="oreilly.class" WIDTH=400 HEIGHT=400>
<PARAM NAME="cabbase" VALUE="ora.cab>
The special parameter name ARCHIVES
is reserved for sending JAR files. JAR files can also be specified using
the ARCHIVES parameter to the
Here's an example:
<APPLET CODE="oreilly.class" WIDTH=400 HEIGHT=400>
<PARAM NAME="archives" VALUE="ora.jar>