The GubcastApplet
(Client)
Gubcast is provided in two variants:
-
The "development" system is available for download at no cost. The
applet supplied with the system pops up a debugging window on the user's
display whenever it starts, prints diagnostic and trace information in
that window as it operates, and removes the window when it stops.
- The "production" system is identical to the development system except
that no debugging window appears on the user's display. It is available
only to developers who have purchased Gubcast licenses from Glass Key
Laboratories.
Unlike most applets, Gubcast itself doesn't add anything of visual interest to
your Web page; it's just a program that runs in the background. So it usually
makes sense to make Gubcast mostly invisible by giving it the smallest
possible height and width; Netscape 4.7 seems to ignore 1x1, so we
recommend 2x2.
Gubcast must be correctly embedded in a page of HTML text in order to run. It
only runs in the Java plug-in; the native Java virtual machines built into
Internet Explorer and Netscape will not execute it. This means that you
can't use the simple <applet>
HTML tags to embed it, but
instead must use the more complex <object>
notation. (See
the Gubdemo HTML for an example.)
Fortunately, Sun provides a utility program called "htmlconv" that
automatically converts applet references encoded in <applet> tags
to the newer standard. You can download this program
here.
We recommend that you write your Gubcast-enabled HTML pages using the
familiar <applet> notation and then use htmlconv to
convert them to the required new format.
The following Gubcast-specific parameters can be supplied in the HTML that
embeds Gubcast in a Web page:
- serverPort: the number of the TCP port on which the server will
be listening for Gubcast client registrations. This parameter is always
required.
- clientPort: the number of the TCP port on which the applet must
listen for connections from the server. If omitted, the next available port
is chosen automatically when the applet starts. clientPort typically
must be specified when the user or server is behind a firewall, so that the
firewall can be directed to let TCP traffic on that port pass. [If, that is,
the Gubcast operator has any control over the configuration of the firewall.
When this is not the case, Gubcast cannot work across the firewall
boundary.]
- name: an application-specific, free-form text string that describes
the client - that is, the context in which the Gubcast applet is running.
Client name must be configured to give the server enough information about
the client to enable it to push the right information to the user at the
right time. For example, it might identify the Web page that the applet is
embedded in and/or include a user account number. Defaults to
"(none)"
.
- pushsound: the name of an audio clip (
.au
) file
defining the sound that the browser is to emit each time a Gubcast message
is received by the applet. The named file must exist within the code base
from which the applet itself was loaded to the browser; that is, if you don't
specify the complete relative or absolute path name of the audio clip file,
it must reside in the same directory as the gubcast.jar
jarfile.
If omitted, Gubcast message arrival will be silent.