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If your question is not answered here or in our bug database, please send email to using our bug reporting template.


Q: I'm having trouble running applets created using Spin.
A: Spin generates perfectly legal and correct Java applets, but we are discouraging people from using Spin to build applets for use on the Internet. At the current time, we are recommending that people use applets only on intranets.

There are a large number of problems in the current browser implementations of Java applets, making it virtually impossible to build Java applets that do anything particularly interesting that will run on even the majority of browsers used on the Internet. Note that this is not a problem with Java, this is a problem with the implementation of Java in popular browsers. A further problem is the current security model for Java applets.

For full information, see the manual Deploying Spin Projects.

Q: Why can't I see the source generated by Spin?
A: Some visual programming tools (for example, Visual Cafe) generate output from source templates, and allow you to see this source code (and even modify it). But Spin generates output from JavaBeans. These JavaBeans components are not instantiated from source at all, so there is no source code to a Spin application.

The only source in a Spin application are the scripts that you may write when you create behaviors. These scripts are what is being compiled when you see the "Grinding Beans" dialog. You have full access to the source for these scripts (in the behaviors). The only other code generated by Spin are event stubs that link JavaBeans together and class stubs for JavaBeans you write. These are not particularly informative to look at.

The price of not being able to see or modify source code is offset by the huge advantages inherent in a component architecture. For example, new JavaBeans can be added to Spin transparently. It would be very difficult to add new source templates to an application generator tool. Also, JavaBeans have their object-oriented advantages, such as being reusable and easier to maintain. One of the reasons component architectures were developed in the first place was to remove the need to mess with source code, and this is especially important in an authoring tool like Spin that is aimed at nonprogrammers.

JavaBean developers have a choice as to whether they distribute source for their components. You can use a JavaBean in Spin even if you do not have access to the source code. Of course, the JavaBean author can choose to distribute source to a bean.

Q: Why does my computer dial my ISP when I run Spin?
A: This occurs only on the Macintosh and only when Spin's debug Web server is enabled. When Spin opens a TCP/IP port for the debug server, your Macintosh thinks that you are trying to use the Internet, so it (helpfully) tries to dial up your ISP for you.

If you are not building a servlet, you can turn Spin's debug server off.

If you are building servlets in Spin, and you don't want your computer to automatically dial up your ISP, you can create a dummy TCP/IP connection on your Macintosh. If you do this, then you will need to switch to the dummy TCP/IP connection when you use Spin, and then switch back when you want to connect to the Internet (luckily, this is fairly painless on a Mac).

To set up a dummy TCP/IP connection, open the TCP/IP control panel and choose "File > Configurations". Duplicate the Default Configuration, and name the new configuration "Spin". Select the Spin configuration. Choose "Make Active". Within the Spin configuration, select the following setting:

Connect via: Ethernet
Configure: Manually
IP Address:
Subnet mask:
Router address: (leave blank)
Name server addr.: (leave blank)
Search domains: (leave blank)
Close the dialog. Click Save. You can now switch between these two configurations as follows:

To set your configuration to normal (to connect to your ISP), open the TCP/IP control panel, select "File > Configurations", choose your original configuration and select "Make Active". Close the control panel.

To set the configuration so Spin will not cause your computer to dial your ISP, open the TCP/IP control panel, select "File > Configurations", choose the Spin configuration and select "Make Active". Close the control panel.

Q: Spin complains about spaces in my CLASSPATH
A: This only affects Windows. The Jikes compiler from IBM, which comes with Spin, will not run if there are any spaces in your CLASSPATH variable. There are three solutions to this problem.

First, and simplest, Spin itself does not actually use the CLASSPATH. If Spin is the only Java application you are using on your computer, you can safely delete the CLASSPATH variable.

If you want to keep your existing CLASSPATH variable, you can change any file (or directory) names that contain spaces to their 8 character DOS-compatible names. For example, if the directory name "Program Files" is in your CLASSPATH, you can change it to "Progra~1".

Alternatively, you can rename or move any files or directories in your CLASSPATH that contain spaces, and then change your CLASSPATH to match.

To edit or delete your CLASSPATH environment variable:

  • On Windows NT this is done with the "system" control panel applet, in the "environment" tab. Be sure to fix CLASSPATH in both system variables and user variables.
  • On Windows 98, you must edit AUTOEXEC.BAT using sysedit (or some other text editor).

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