Using CA AppLogic® › Appliance Developer Guide › Creating Appliances › Create a Singleton

Create a Singleton

After you select the template, create a new singleton class for your appliance. Branching a class lets you create a new singleton class for your appliance. You may use an existing template class rather than create the new appliance from scratch. Consider using the template class when you want to add additional functionality to an existing class. For example, upgrade to a newer version or provide additional parameterization capabilities. To branch a class, select the class instance that you want to branch, right-click the mouse, and select Branch Class from the context menu, or click the Appliance menu item and select Branch Class.

Important! Configure the new singleton to require a minimum of 128M of memory to run, even if the planned software for installation does not require this amount of memory. You can change the resource requirement after the installation of software on the new appliance completes. However, it is critical to have the extra memory during installation because the base appliance images (like LUX) do not have swapping enabled and package installers require a lot of memory to work. In particular, yum is known not to work with less than 96Mb of system memory.

To create a singleton class

1. Create a new application.

   You can also use an existing application, such as the sample app.

2. Drag the template that you chose in the previous step from the global catalog to the canvas.
3. Right-click the instance shape on the canvas, and click Branch Class.

   The Class Branch dialog displays the percentage completion for each copied volume. When the branch operation completes, the status dialog displays the Successfully branched class message.

4. Confirm that you can save the application.

   Important! Wait until the branch operation completes and reloads the application.

   Note: When you try to branch a class and a second warning window appears that displays a message that there is no instance volume already copied, select OK to proceed. In this case, the branch process may take a few minutes, as CA AppLogic® is making copies of the appliance volume.

   You now have a singleton class ready for customization.

After you create, configure, and test the new singleton class, drag it into a global catalog so that other applications may use the new class. You can also drag it into the local catalog of the application, so that it may be instantiable by your application, in the case where multiple instances of the class can be used in the application.