• Overview of the sample
• How to use this sample
• Troubleshooting this sample
• Files in this sample

To see:

• the sample as an applet, see javabeep.html.
• the sample as a standalone application, follow the instructions in javabeepframe.html.
• the source code, click here.

See the

To see the sample as a standalone

BEEPER.DLL is a simple Automation server. It is one of the samples from the ActiveX^™ Template Library (ATL). You can download ATL from the Web (www.microsoft.com/visualc/v42/atl/).

Beeper has two methods and one property of interest.

• In response to calling the Beep method, Beeper plays the default system sound five out of six times. Every sixth call fails.
• The getItem method returns a String.
• The read-only Count property gives the number of different strings getItem will return.

About the sample

javabeep creates a Beeper object (COM component). It calls the Beep method of Beeper in response to mouseDown events. If the call succeeds, Beeper plays the default system sound. javabeep then calls getItem to get a series of strings from Beeper. It displays the set of strings at the location of the mouseDown. If the call fails (as it will every sixth time), no system sound occurs. In response, javabeep places an error message at the location of the mouseDown event.

See javabeep.start for creating the beeper COM component. See javabeep.mouseDown for the calls to the beeper COM component and handling the failure of the call to Beep. Use ClassView to help you find these methods.

About security

COM components can access any system resources. As such, they are both very powerful and potentially very dangerous. In the Java virtual machine (VM) in Microsoft^® Internet Explorer 3.0 only trusted class files can use COM components. Class files from digitally signed CAB files are trusted.

If the HTML file is run from Microsoft Developer Studio, the class files are also trusted. This can be very helpful during applet development. However, to deliver your applet to other users, you must put it in a signed CAB file.

The code for the applet itself is taken from the JavaBeep sample. For more information on the Java code and the server, see the JavaBeep sample.

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1. Register BEEPER.DLL, the COM component for this sample.
   See Registering a COM Component.
2. Create a Java interface for the COM component.
   See Creating a Java Interface for a COM component.
3. In Explorer, double-click the WVTSTON.REG file to enable test certificates on this machine.
4. In Explorer, double-click the JAVABEEP.HTML file to open it.

To create your own CAB file and sign it:

1. Create a CAB file with your CLASS files.
   See Making Cabinets.
2. Create a test certificate (this needs to be done only once).
   See Creating a Test Certificate.
3. Sign the CAB file with your certificate.
   See Signing a Program File.

To use the .CLASS files from a CAB file:

• Add a parameter to the <APPLET> tag naming the CAB file.

For example:

     <param name="cabbase" value="firstcab.cab">

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• Create a Java interface for the COM server.

If you get the error message UnsatisfiedLinkError:

• Register the COM server.

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